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CLD

[00006] CLD–PLATO IV COMMUNICATION LINK DRIVER
[00033] DIRECT CELL ASSIGNMENTS
[00149] MAIN PROCESSING LOOP
[00191] PROCESS REQUEST
[00241] RESERVE LINK
[00283] RESERVE LOCAL EQUIPMENT AND CHANNEL
[00335] RELEASE LOCAL EQUIPMENT AND CHANNEL
[00374] REMOTE STARTUP
[00426] SEND AND RECEIVE A MESSAGE
[00452] DE-ESTABLISH LINK
[00542] SPECIAL ROUTINES
[00554] LOOPBACK TEST
[00619] LOCAL TERMINAL MODE DRIVER
[00662] TERMINAL MODE IO
[00720] GET KEY FROM ECS KEY BUFFER
[00793] SEND FRAME TO PLATO
[00869] MOVE FRAME
[00913] REMOTE TERMINAL MODE DRIVER
[00972] TERMINAL MODE IO
[01013] SEND KEY TO PLATO
[01153] GET FRAMES FROM ECS
[01239] MOVE KEY
[01360] TERMINAL MODE INPUT-OUTPUT
[01478] READ ECS
[01568] WRITE ECS
[01664] CLOCK
[01715] READ AND CLEAR PPU COMMUNICATIONS SWITCH
[01757] WRITE TO CM BUFFER.
[01798] CHARACTER I/O
[01930] WAIT CHARACTER READY OR REQUEST
[01986] ODD CHANNEL STATUS/PUT CHARACTER
[02039] GETCHR
[02100] PACK DATA
[02155] UNPACK
[02207] DATAIN
[02311] DATAOUT
[02366] SEND MESSAGE
[02419] RECEIVE A MESSAGE
[02475] SELECT 6681 DATA CONVERTER
[02566] SYNCHRONIZATION ESTABLISH
[02621] DIVIDE BY 5
[02648] INCREMENT 5 BYTE COUNTER
[02684] PARITY GENERATION
[02738] PAUSE–CHECK FOR STORAGE MOVE OR ERROR CONDITIONS
[02829] SOFTWARE AND HARDWARE ERROR ROUTINES
[02876] EXIT ROUTINES
[02899] SEND END LINK
[02946] TERMINAL MODE TERMINATION
[02991] SEND PLATO REQUEST
[03035] PROCESS 3266 INPUT
[03064] WAIT ON LINKCTL
[03088] EQUATES
[03131] STORAGE DEFINITIONS
[03208] COMMUNICATION BUFFERS
[03306] COMMUNICATION BUFFERS
[03343] ERROR CODES
[03372] COMMAND CODES AND CONTROL CHARACTERS
[03419] 6681 AND 311-B CODES
[03459] INITIALIZATIONS
Source Code

CLD 
* /---   FILE TYPE = E
* /---   BLOCK      CLD        00 000   78/02/06  11.43 
          IDENT  CLD,CLD
*                            CZZ
          TITLE  CLD--PLATO IV COMMUNICATION LINK DRIVER
          PERIPH
          SST    FNTL 
          COMMENT LINK DRIVER 
* 
*CALL     COMPMAC 
*CALL      PTEXT
*CALL     PLAP501 
* 
*CALL     AIDTEXT 
 
          QUAL   CPS
*CALL COMSCPS 
          QUAL   *
 PORT     MACRO  P1 
          LOCAL  N,N1 
 N        VFD    12/7700B+C=CH
 IFEO     IFC    EQ,*P1*EVEN* 
 N1       VFD    12/5100B+E=CH
          CHAN   E=CH,N1
 IFEO     ELSE
 N1       VFD    12/5101B+O=CH
          CHAN   O=CH,N1
 IFEO     ENDIF 
          CHAN   C=CH,N 
          ENDM
* /---   BLOCK      DIRECT     00 000   76/05/13  14.53 
          TITLE  DIRECT CELL ASSIGNMENTS
************************************************************************
 T0       EQU    0           *
* 
 T1       EQU    1           *
* 
 T2       EQU    2            * 
* 
 T3       EQU    3           * TEMPORARY STORAGE
* 
 T4       EQU    4           *
* 
 T5       EQU    5           *
* 
 T6       EQU    6           *
* 
 T7       EQU    7           *
* 
 CM       EQU    10B         CM WORD BUFFER(5 WORDS)
* 
 LA       EQU    15B         PP PACKAGE LOAD ADDRESS
* 
 T8       EQU    16B         TEMPORARY STORAGE
* 
 T9       EQU    17B         TEMPORARY STORAGE
* 
 FUNC     EQU    20B         CURRENT REQUEST FUNCTION.
* 
 CHAR     EQU    21B         LAST CHARACTER INPUT 
* 
 NC       EQU    22B         NUMBER OF TIMES TO CHECK FOR 
*                            CHARACTER READY. 
 TI       EQU    23B         COUNTER SET IN PAUSE SO THAT 
*                            WE DO NOT LOOP TO LONG IN
*                            CHARARCTER STATUS ROUTINES 
*                            WITHOUT CHECKING FOR STORAGE 
*                            RELOCATION.
 NAKFLAG  EQU    24B         0=LAST BLOCK RECEIVED OKAY 
*                            1=ERROR IN LAST BLOCK
 LT       EQU    25B         NUMBER CM WORDS IN LAST
*                            LINKCTL COMMAND. 
 DL       EQU    26B         NUMBER OF CM DATA WORDS IN 
*                            COMMUNICATION BUFFER.
 D0       EQU    27B         TEMPORARY STORAGE
* 
 KEY      EQU    30B         POINTER TO NEXT KEY TO SEND
*                            WHEN IN TERMINAL MODE. 
 FRAME    EQU    31B         POINTER TO NEXT FRAME TO SEND
*                            WHEN IN TERMINAL MODE
 MODE     EQU    32B         =0 FOR FILE TRANSFER MODE
*                            =1 FOR TERMINAL MODE 
 RESEND   EQU    33B         NUMBER OF TIMES A MESSAGE HAS
*                            BEEN RESENT. 
 TT       EQU    34B         TEMPORARY STORAGE
* 
 SC       EQU    35B         SYNC CODE COUNTER
* 
 OC       EQU    36B         OUTPUT CHARACTER 
* 
* /---   BLOCK      DIRECT     00 000   78/01/05  09.02 
 ULP      EQU    37B         UPPER-LOWER POINTER FOR PACKING
* 
 ULU      EQU    40B         UPPER-LOWER POINTER FOR
*                            UNPACKING. 
 WP       EQU    41B         PPU WORD CURRENTLY BEING PACKED
* 
 WU       EQU    42B         PPU WORD CURRENTLY BEING 
*                            UNPACKED.
 NW       EQU    43B         NUMBER OF PPU WORDS IN THIS
*                            MESSAGE. 
 CKO      EQU    44B         LONGITUDINAL PARITY WORD FOR 
*                            OUTPUT DATA. 
 CKI      EQU    45B         LONGITUDINAL PARITY WORD FOR 
*                            INPUT DATA.
 FRCHK    EQU    46B         TIME OUT COUNTER FOR READING 
*                            FRAMAT STATUS WORD 
 SENDI    EQU    47B         SEND KEY INDEX 
*                            EOD,EOB, OR EOF. 
 IR       EQU    50B         INPUT REGISTER(5 WORDS)
* 
 RA       EQU    55B         REFERENCE ADDRESS/100
* 
 FL       EQU    56B         FIELD LENGTH/100 
* 
 ECS      EQU    60B         POINTER TO ECS ADDRESS FOR 
*                            READ AND WRITE ECS ROUTINES
 STATION  EQU    61B         STATION NUMBER OF LINKCTL
* 
 BADC     EQU    62B         CONSECUTIVE BAD CHAR. COUNT. 
* 
 ECSOFF   EQU    63B         OFFSET TO BE ADDED TO BASE 
*                            ECS ADDRESS
 TIME     EQU    64B         TIME-OUT COUNTER FOR TERMINAL
*                            MODE, NO CHAR. READY STATUS. 
 PS       EQU    65B         HARDWARE STATUS
* 
 TMSTAT   EQU    66B         TERMINAL MODE STATION
* 
 CLK      EQU    67B         LAST CLOCK TIME
* 
 ON       EQU    70B         CONSTANT 1 
* 
 HN       EQU    71B         CONSTANT 100 
* 
 TH       EQU    72B         CONSTANT 1000
* 
 TR       EQU    73B         CONSTANT 3 
* 
 CP       EQU    74B         CONTROL POINT ADDRESS
* 
 IA       EQU    75B         INPUT REGISTER ADDRESS 
* 
 OA       EQU    76B         OUTPUT REGISTER ADDRESS
* 
 MA       EQU    77B         MESSAGE BUFFER ADDRESS 
* /---   BLOCK      MAIN LOOP  00 000   78/05/11  21.44 
          TITLE  MAIN PROCESSING LOOP 
          ORG    PPFW 
* 
 CLD      BSS    0           CZZ
* 
* * *     PERFORM INITIALIZATIONS 
* 
          RJM    INITIAL
          CALL   PARGEN      GENERATE PARITY TABLE
* 
* * *     CHECK TO SEE IF IT IS NECESSARY TO PAUSE
*         FOR STORAGE RELOCATION. 
* 
 MAIN     BSS    0
          RJM    PAUSE       CHECK FOR PAUSE CONDITIONS 
* 
* * *     PROCESS ANY 3266 INPUT
          CALL   LOOPCHK
* 
* * *     CHECK FOR DROP SIGNAL FROM PLATO LESSON 
* 
          CALL   DROPCHK
* 
* * *     CHECK FOR  REQUEST PENDING
*         ON RETURN IF -A- IS ZERO NO NEW REQUEST 
* 
          RJM    READSW 
          ZJN    MAIN        NO NEW REQUEST 
          STD    LT          SAVE LENGTH OF NEW REQUEST 
* 
* * *     READ REQUEST FROM CM TO -IBF- 
* 
          RJM    READ 
* 
* * *     PROCESS NEW REQUEST 
* 
          RJM    PROC 
* 
* * *     WAIT FOR NEW REQUEST
* 
          UJN    MAIN 
* 
          TITLE  PROCESS REQUEST
* 
* * PROC
* 
*         THIS ROUTINE DETERMINES  WHAT FUNCTION IS BEING 
*         REQUESTED AND JUMPS TO THE CORRECT ROUTINE TO 
*         PROCESS IT.  IF AN ILLEGAL FUNCTION CODE IS 
*         RECEIVED AN ERROR CODE IS PLACED INTO THE 
*         RESPONSE AND THE REQUEST IS MARKED DONE.
* 
 PROC     SUBR
* 
* * *     ISOLATE FUNCTION CODE 
* 
          LDM    IBF+RFUNC
          STD    FUNC 
* 
* * *     CHECK FOR LEGAL FUNCTION
* 
          SBN    FLST        SUBTRACT HIGHEST LEGAL CODE+1
          PJN    PRERR       JUMP IF OUT OF RANGE 
* 
* * *     JUMP TO PROCESS 
* 
 PROCE    BSS    0
          LDM    PTABLE,FUNC
          STD    D0 
          LJM    0,D0 
* 
* * *     JUMP TABLE FOR FUNCTION CODE PROCESSING 
* 
 PTABLE   BSS    0
          VFD    12/STUP     00 CHECK FOR STARTUP 
          VFD    12/PRES     01 RESERVE LINK
          VFD    12/MESSIO   02 SEND AND RECEIVE MESSAGE
          VFD    12/PREL     03 RELEASE LINK
          VFD    12/STCOMD   04 RETURN 311 STATUS 
          VFD    12/STATS    05 RETURN DRIVER STATISTICS
          VFD    12/TEST     06 RUN SPECIAL ROUTINE 
          VFD    12/LTLINK   07 LOCAL TERMINAL MODE DRIVER
          VFD    12/RTLINK   10 REMOTE TERMINAL MODE DRIVER 
          VFD    12/PRERR 
          VFD    12/TLOP     12 LOOP BACK TEST
 FLST     EQU    *-PTABLE 
* 
* * *     ERROR--ILLEGAL FUNCTION CODE
* 
 PRERR    BSS    0
          CALL   SERROR,SIFC
* /---   BLOCK      PRES       00 000   77/10/01  00.02 
          TITLE  RESERVE LINK 
* 
* *PRES 
* 
*         THIS ROUTINE ATTEMPTS TO RESERVE THE LOCAL
*         AND REMOTE COMMUNICATION EQUIPMENT. 
* 
 PRES     BSS    0
* 
* * *     GET AND SAVE LINKCTL STATION NUMBER 
* 
          LDM    IHDR+STNO
          STD    STATION
* 
* * *     SAVE PLATO*S ECS RA 
          LDM    XECU 
          STM    ECU
          LDM    XECL 
          STM    ECL
* 
* * *     IS LINK ALREADY IN SYNC 
* 
          LDM    SFLAG
          NJP    MESSIO      JUMP IF YES
* 
* * *     RESERVE LOCAL EQUIPMENT FIRST.
* 
          RJM    LRES 
* 
* * *     SETUP 6681
* 
 PRES0    BSS    0
          RJM    SELDC
* 
* * *     WAIT FOR SYNCHRONIZATION TO BE ESTABLISHED
* 
          CALL   SEST,2400
* 
* * *     SEND START-UP MESSAGE 
* 
          LJM    MESSIO 
* /---   BLOCK      LRES       00 000   77/08/29  15.39 
          TITLE  RESERVE LOCAL EQUIPMENT AND CHANNEL
* 
* *LRES 
* 
*         THIS ROUTINE ATTEMPTS TO RESERVE THE COMMUNICATION
*         LINK BY RESERVING EQUIPMENT -CL- AND  CHANNEL 
*         -CH-. 
* 
 LRES     SUBR
* 
* * *     DO NOT RESERVE EQUIPMENT IF ALREADY RESERVED
          LDC    ALSEVEN
          SBM    CLEQ 
          NJN    LRESX       IF EQUIPMENT ALREADY RESERVED
* 
* * *     FIND EQUIPMENT ORDINAL AND CHANNEL NUMBER.
          LDC    2RCL 
          CALL   EQN
          MJP    LRES1       JUMP IF EQUIP NOT AVAILABLE
          STD    CM+1        SAVE EQUIPMENT ORDINAL 
          LDD    CM          GET CHANNEL NUMBER 
          STD    TT          SAVE IT. 
* 
* * *     RESERVE CHANNEL AND EQUIPMENT 
          MONITOR REQM       RESERVE EQUIPMENT
          LDD    CM+1        READ REPLY 
          ZJP    LRES1       JUMP IF EQUIP ALREADY RESERVED 
          STM    CLEQ        SAVE ORDINAL 
* 
          LDD    TT          GET CHANNEL NO.
          RCHAN 
          LDD    CM+1        CHECK MONITOR REPLY
          ZJP    LRES2       JUMP CHANNEL NOT AVAILABLE 
          STM    CLCH        SAVE CHANNEL NUMBER
* 
* * *     PLUG CHANNEL AND PORT NUMBERS 
          PLANT  CHANNEL,C=CH PLUG CHANNEL NUMBER.
          LDM    XPORTCH     GET 311 CHANNEL NUMBER 
          PLANT  CHANNEL,E=CH PLUG CHANNEL NUMBER.
          LDM    XPORTCH
          ADN    1           MAKE ODD CHANNEL NUMBER
          PLANT  CHANNEL,O=CH PLUG ODD CHANNEL. 
          LJM    LRESX
* 
* * *     ERROR--EQUIPMENT ALREADY RESERVED 
 LRES1    BSS    0
          CALL   SERROR,SENA
* 
* * *     ERROR--CHANNEL ALREADY RESERVED 
 LRES2    BSS    0
          CALL   SERROR,SCNA
* /---   BLOCK      LREL       00 000   77/08/29  15.40 
          TITLE  RELEASE LOCAL EQUIPMENT AND CHANNEL
* 
* *LREL 
* 
*         THIS ROUTINE RELEASES THE RESERVE ON THE LOCAL
*         COMMUNICATION LINK EQUIPMENT -CL- AND THE 
*         ASSOCIATED CHANNEL(C=CH) IF IN FACT THEY HAVE 
*         BEEN RESERVED.
* 
 LREL     SUBR
* 
* * *     HAS -CL- BEEN RESERVED
          LDC    ALSEVEN
          SBM    CLEQ 
          ZJN    LREL1       JUMP IF NOT
* 
* * *     RELEASE EQUIPMENT 
          LDM    CLEQ        GET EST ORDINAL OF -CL-
          STD    CM+1 
          MONITOR DEQM       RELEASE THE EQUIPMENT
* 
* * *     CHECK IF CHANNEL HAS BEEN RESERVED
 LREL1    BSS    0
          LDC    ALSEVEN
          SBM    CLCH        CHECK CHANNEL FLAG 
          ZJN    LREL2       IF ALL SEVENS CHANNEL HAS NOT
*                            YET BEEN RESERVED
* 
* * *     RELEASE CHANNEL 
          LDM    CLCH 
          DCHAN 
* 
* * *     SET INDICATORS SHOW NO EQUIPMENT RESERVED 
 LREL2    BSS    0
          LDC    ALSEVEN
          STM    CLEQ 
          STM    CLCH 
          UJN    LRELX
* /---   BLOCK      STARTUP    00 000   78/03/30  10.23 
          TITLE  REMOTE STARTUP 
* 
* * STUP
* 
*         CHECK TO SEE IF REMOTE SITE IS REQUESTING 
*         USE OF LINK.  IF SO SEND ACKNOWLEDGE AND
*         INFORM LINKCTL. 
* 
 STUP     BSS    0
* 
* * *     GET AND SAVE LINKCTL STATION NUMBER 
* 
          LDM    IHDR+STNO
          STD    STATION
* 
* * *     SAVE PLATO*S ECS RA 
          LDM    XECU 
          STM    ECU
          LDM    XECL 
          STM    ECL
* 
* * *     IS LINK ALREADY IN SYNC 
* 
          LDM    SFLAG
          NJP    STUP1       JUMP IF YES
* 
* * *     RESERVE LOCAL EQUIPMENT 
* 
          RJM    LRES 
* 
* * *     SET UP 6681 
* 
          RJM    SELDC
* 
* * *     ESTABLISH SYNCHRONIZATION 
* 
          CALL   SEST,750 
* 
* * *     SET SYNC CODE COUNTER TO ZERO 
* 
 STUP1    BSS    0
          LDN    0
          STD    SC 
* 
* * *     CHECK FOR MESSAGE.
* 
          CALL   MESSIN 
* 
* * *     RECEIVED STARTUP MESSAGE INFORM LINKCTL.
* 
          CALL   WRITE
          LJM    PROCX
          TITLE  SEND AND RECEIVE A MESSAGE 
* 
* * MESSIO
* 
*         SEND MESSAGE TO REMOTE SITE AND WAIT FOR
*         A RETURNING MESSAGE.
* 
 MESSIO   BSS    0
* 
* * *     MAKE SURE REMOTE STILL IN TOUCH 
* 
          CALL   SEST,2 
* 
* * *     OUTPUT MESSAGE
* 
          CALL   MESSOUT
* 
* * *     WAIT FOR RESPONSE 
* 
          CALL   MESSIN 
* 
* * *     SEND MESSAGE TO LINKCTL 
* 
          CALL   WRITE
          LJM    PROCX
* /---   BLOCK      REL/STATUS 00 000   77/10/02  22.39 
          TITLE  DE-ESTABLISH LINK
* 
* *PREL 
* 
*         RELEASE REMOTE AND LOCAL COMMUNICATION EQUIPMENT. 
* 
 PREL     BSS    0
* 
* * *     MAKE SURE REMOTE IS STILL IN TOUCH
* 
          CALL   SEST,2 
* 
* * *     SEND EOT MESSAGE TO REMOTE SITE 
* 
          CALL   MESSOUT
* 
* * *     INFORM -LINKCTL- THAT THE REQUEST IS COMPLETE 
* 
          RJM    WRITE
          LJM    PROCX       WAIT FOR NEXT COMMAND
          SPACE  2
* 
* * STCOMD
* 
*         THIS ROUTINE INPUTS THE STATUS FROM BOTH THE ODD
*         AND EVEN CHANNELS AND RETURNS IT TO -LINKCTL-.
* 
 STCOMD   BSS    0
          LDM    IHDR+STNO
          STD    STATION
* 
* * *     RESERVE EQUIPMENT AND CHANNEL 
* 
          RJM    LRES 
          RJM    SELDC
* 
* * *     GET ODD CHANNEL STATUS
* 
          CALL   ICHR2
          STM    OBF+RSTA    SAVE FOR THE RESPNSE 
* 
* * *     GET EVEN CHANNEL STATUS 
* 
          RJM    ICHR 
          STM    OBF+RSTA1   PUT INTO RESPONSE
* 
* * *     SEND RESPONSE TO LINKCTL
* 
          RJM    WRITE
          LJM    PROCX       WAIT FOR NEXT COMMAND
          EJECT 
* 
* 
* * STATS 
* 
*         THIS ROUTINE PASSES ALL STATISTICS CELLS
*         TO -LINKCTL-. 
* 
 STATS    SUBR
* 
* * *     MOVE STATISTICS CELLS TO COMMUNICATION BUFFER 
* 
          LDM    PECNT
          STM    DSTATS 
          LDM    BDCNT
          STM    DSTATS+4 
          LDM    LPCNT
          STM    DSTATS+9 
          LDM    SCCNT
          STM    DSTATS+14
          LDM    BCCNT
          STM    DSTATS+19
          LDN    0
          STM    PECNT
          STM    BDCNT
          STM    LPCNT
          STM    SCCNT
          STM    BCCNT
* 
* * *     SET NUMBER OF WORDS USED IN DATA SECTION
*         OF COMMUNICATION BUFFER 
* 
          LDN    6
          STD    DL 
* 
* * *     SEND RESPONSE 
* 
          RJM    WRITE
          LJM    PROCX       WAIT FOR NEXT COMMAND
* 
          TITLE  SPECIAL ROUTINES 
* 
* * SPEC
* 
*         FUNCTION CODE RESERVED FOR SPECIAL FUNCTIONS
* 
 SPEC     BSS    0
* 
* * *     SEND RESPONSE 
          RJM    WRITE
          LJM    PROCX       WAIT FOR NEXT COMMAND
* /---   BLOCK      TLOP       00 000   77/09/22  00.37 
          TITLE  LOOPBACK TEST
* 
* * TLOP
* 
*         TEST LOOP BACK TO MAKE SURE DATA IS BEING SENT
*         AND RECEIVE AT THIS SITE PROPERLY, ALSO CHECKS
*         TELEPHONE EQUIPMENT.
* 
 TLOP     BSS    0
          LDM    IHDR+STNO
          STD    STATION
* 
* * *     RESERVE LOCAL EQUIPMENT 
          RJM    LRES 
* 
* * *     SETUP 6681
          RJM    SELDC
* 
* * *     ESTABLISH SYNCHRONIZATION 
          CALL   SEST,100 
* 
* * *     SET TO OUTPUT 100 CHARACTERS OF DATA
          LDC    99 
          STD    SC 
* 
* * *     WAIT FOR CHARACTER READY OR CHARACTER REQUEST 
 NTL1     BSS    0
          CALL   WCR,MCRQ+MCRD
          SHN    6
          MJN    NTL2        JUMP IF CHARACTER READY
* 
* * *     OUTPUT A CHARACTER
          LDM    XPATTRN
          CALL   PUTCHR 
          UJN    NTL1 
* 
* * *     SAVE INPUT CHARACTER IN DATA BUFFER FOR LINKCTL 
 NTL2     BSS    0
          LDD    CHAR 
          STM    DBUFF,SC 
* 
* * *     INFINITE LOOP OR ONLY A HUNDRED 
          LDM    XLOOPS 
          NJP    NTL1        JUMP IF INFINITE LOOP
* 
* * *     HAVE 100 CHARACTERS BEEN OUTPUT 
          SOD    SC 
          PJN    NTL1        JUMP IF NOT
* 
* * *     SET TO PASS ALL INPUT TO LINKCTL
          LDN    21 
          STD    DL 
* 
* * *     SEND RESPONSE 
          RJM    WRITE
          LJM    PROCX       WAIT FOR NEXT COMMAND
* /---   BLOCK      TEST       00 000   78/01/04  10.52 
* 
* *       SPECIAL TEST ROUTINES 
* 
          EJECT 
 TEST     BSS    0
          LJM    PROCX       WAIT FOR NEXT COMMAND
 
* /---   BLOCK      LTLINK     00 000   78/01/05  09.03 
          TITLE  LOCAL TERMINAL MODE DRIVER 
* 
* * LTLINK
* 
*         THIS ROUTINE COMMUNICATES WITH PLATO AT THE SYSTEM
*         LOCAL TO THE TERMINAL.  ITS JOB IS TO GET 
*         KEYS FROM PLATO AND SEND THEM OVER THE LINK TO THE
*         REMOTE SYSTEM, WHILE AT THE SAME TIME ACCEPTING 
*         FRAMES FROM THE LINK AND PUTTING THEM INTO
*         FRAMERS LINK BUFFER.
* 
 LTLINK   BSS    0
* 
* * *     SET MASKS IN -TMIN- AND -TMOUT- 
          LDN    1
          STM    TOMK        SET TO 1, FOR KEY OUTPUT 
          LDN    3
          STM    TIMK        SET TO 3, FOR FRAME INPUT
* 
* * *     DO INITIALIZATIONS
          CALL   TMSTART
* 
* * *     CHECK IF TIME TO SEND KEY OR GET FRAME
 LT0      BSS    0
          CALL   CLOCK,7
          NJN    LT1
* 
* * *     TALK TO PLATO THROUGH ECS 
          CALL   SENDFRM     SEND FRAME TO PLATO
          CALL   LCHK        SERVICE COMMUNICATION EQUIP. 
          CALL   GETKEY      CHECK FOR KEY INPUT
          CALL   FRMOVE      READY ANOTHER FRAME IF ONE.
 LT1      BSS    0
          CALL   LCHK        SERVICE COMMUNICATION EQUIP. 
* 
* * *     IS IT TIME TO CHECK FRAMAT STATUS 
          SOD    FRCHK
          NJP    LT0
* 
* * *     CHECK FOR FRAMAT RE-INITIALIZING
          CALL   FRMCHK 
          UJP    LT0
* /---   BLOCK      LCHK       00 000   84/11/15  11.33 
          TITLE  TERMINAL MODE IO 
* 
* * LCHK
* 
*         'CHECK COMMUNICATION EQUIPMENT TO SEE IF INPUT
*         WAITING OR READY TO SEND OUTPUT.
* 
 LCHK     SUBR
* 
* * *     CHECK FOR CHARACTER READY  OR CHARACTER REQUEST 
          CALL   WCR,MCRD+MCRQ
          ZJN    LCHKX       IF NEITHER STATUS APPEARED 
          SHN    6
          PJN    LCHK1       JUMP IF CHARACTER REQUEST
* 
* * *     CHECK FOR BUFFER OVERFLOW 
          LDD    ULP         NEXT *IN* POINTER
          ADN    CHPF        CHARACTERS PER FRAME 
          SBD    FRAME       NEXT *OUT* POINTER 
          LPC    TMASK       KEEP IN RANGE
          ZJP    OVERFLOW 
* 
* * *     CHARACTER READY STATUS - PROCESS INPUT
          CALL   TMIN 
          MJN    LCHKX       IF ONLY SYNC CHARACTER 
* 
* * *     MOVE FRAME TO -FRBUFF- IF NECESSARY OR POSSIBLE 
          LDM    FRBUFF 
          NJN    LCHKX       IF ALREADY FILLED
          CALL   FRMOVE      READY NEXT FRAME 
 LCHK2    UJN    LCHKX
* 
* * *     CHECK CHARACTER IN TIME OUT 
 LCHK1    BSS    0
          AOD    TIME        BUMP TIME OUT COUNTER
          ADC    -ALSEVEN    CHECK VALUE OF COUNTER 
          ZJP    LOSTC       JUMP IF TIMED OUT
* 
* * *     DO WE HAVE OUTPUT TO SEND 
          LDD    KEY
          SBD    ULU
          ZJN    LCHK2       IF NO OUTPUT 
* 
* * *     SEND KEY TO REMOTE SYSTEM 
          CALL   TMOUT
          UJN    LCHK2
* 
* * *     INCREMENT OVERFLOW COUNTER
 OVERFLOW BSS    0
          AOM    OVER 
          LOADCM COMBF
          ADN    3
          CWM    OVER,ON
          UJN    LCHK2
* * 
 OVER     BSSZ   1
          DIS    ,*OVERFLOW*
* /---   BLOCK      GETKEY     00 000   77/10/02  23.04 
          TITLE  GET KEY FROM ECS KEY BUFFER
* 
* * GETKEY
* 
*         THE KEY BUFFER CORRESPONDING TO THE TERMINAL
*         MODE STATION (TMSTAT) IS CHECK.  'IF A NEW
*         KEY IS PRESENT IT IS MOVED TO THE LINK OUTPUT 
*         BUFFER AND THE CPU INDEX IS INCREMENTED BY
*         ONE.  THE SECOND WORD OF THE KEY BUFFER IS THEN 
*         WRITTEN BACK TO ECS TO UPDATE THE CPU INDEX.
* 
*         FORMAT OF KEY BUFFER';
*         / KEY / KEY / KEY / KEY / PPU INDEX / 
*         / PRESS AND TIMING KEYS / CPU INDEX / 
* 
 GETKEY   SUBR
* 
* * *     CALCULATE OFFSET TO LINK STATIONS KEY BUFFER
          LDD    TMSTAT 
          SHN    1           TWO WORDS PER STATION
          STD    ECSOFF 
* 
* * *     READ THE KEY BUFFER FROM ECS
          LDN    2
          STD    ECS         NUMBER OF CM WORDS TO READ 
          CALL   READECS,PKEYECS
* 
* * *     ARE THERE ANY NEW KEYS
          LDM    LKBUF+4     PPU INDEX (INPUT PTR)
          SBM    LKBUF+9     CPU INDEX (OUTPUT PTR) 
          ZJN    GETKEYX     IF NO NEW KEYS 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   LCHK 
* 
* * *     INCREMENT CPU INDEX AND LOCATE NEXT KEY 
          AOM    LKBUF+9
          LPN    3           MASK INDEX FOR MOD 4 
          STD    D0 
          LDM    LKBUF,D0    GET KEY
          STM    KYBUFF      SAVE KEY 
* 
* * *     MOVE SECOND WORD OF KEY BUFFER TO FIRST 
*         WORD OF PPU BUFFER SO IT CAN BE WRITTEN BACK. 
* 
          LDN    4
          STD    D0 
 GK1      BSS    0
          LDM    LKBUF+5,D0 
          STM    LKBUF,D0 
          SOD    D0 
          PJP    GK1         JUMP IF NOT ALL MOVED
* 
* * *     WRITE BACK TO ECS 
          AOD    ECSOFF      POINT TO CPU WORD
          LDN    1
          STD    ECS         WRITE ONE WORD 
          CALL   WRITECS,PKEYECS
* 
* * *     MOVE NEW KEY TO OUTPUT BUFFER 
          LDD    KEY         LOAD CHARACTER POSITION
          SHN    -1          DIVIDE BY TWO, WORD POSITION 
          STD    TT          SAVE 
          LDM    KYBUFF      GET NEW KEY
          STM    ISTART,TT    MOVE TO OUTPUT BUFFER.
* 
* * *     MOVE POINTER TO NEXT AVAILABLE SPOT.
          LDD    KEY         GET POINTER
          ADN    CHPK        TWO CHARACTERS/KEY 
          LPC    TMASK       KEEP MOD 128 
          STD    KEY
          LJM    GETKEYX
* /---   BLOCK      SENDFRM    00 000   77/10/03  14.24 
          TITLE  SEND FRAME TO PLATO
* 
* * SENDFRM 
* 
*         IF A FRAME HAS BEEN RECEIVED FROM THE REMOTE
*         SYSTEM THIS ROUTINE WILL APPEND THE TERMINAL
*         MODE STATION NUMBER (TMSTAT) AND GIVE IT
*         TO THE FRAMER FOR OUTPUT TO THE APPROPRIATE 
*         STATION.  THE BUFFER (LINKIO) IS A CIRCULAR 
*         BUFFER INTO WHICH THE PPU WRITES THE FRAMES 
*         AND FROM WHICH THE FRAMER REMOVES THEM.  LKIN 
*         CONTROLS INPUT TO THE BUFFER WHILE LKOUT
*         CONTROLS REMOVAL OF INFORMATION FROM THE BUFFER.
* 
*         INPUT PARAMETERS';
*         (FRBUFF) = FRAME OR 0 IF NONE READY 
* 
 SENDFRM  SUBR
* 
* * *     IS THERE A FRAME READY TO GIVE TO FRAMER
          LDM    FRBUFF 
          ZJN    SENDFRMX 
* 
* * *     READ IN/OUT POINTERS FROM ECS 
          LDN    0
          STD    ECSOFF 
          LDN    2
          STD    ECS
          CALL   READECS,LKIN 
* 
* * *     CHECK FOR BUFFER FULL 
          LDM    LKBUF+4     IN POINTER 
          ADN    1           BUMP TO NEXT WORD
          SBM    LKBUF+9     OUT POINTER
          LPC    LKMASK      BUFFER LENGTH MASK 
          ZJN    SENDFRMX    IF BUFFER FULL 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   LCHK 
* 
* * *     MOVE FRAME TO LKBUF FOR TRANSFER TO ECS 
          LDM    FRBUFF 
          STM    LKBUF
          LDM    FRBUFF+1 
          STM    LKBUF+1
* 
* * *     ADD STATION NUMBER
          LDD    TMSTAT 
          STM    LKBUF+2
* 
* * *     DETERMINE OFFSET IN LINKIO BUFFER 
          LDM    PFRAME+4 
          LPC    LKMASK      BUFFER LENGTH MASK 
          STD    ECSOFF 
* 
* * *     WRITE NEW FRAME TO ECS
          LDN    1
          STD    ECS         NUMBER OF WORDS TO WRITE 
          CALL   WRITECS,LINKIO 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   LCHK 
* 
* * *     INCREMENT LINKIO PPU POINTER
          CALL   AFIVE,PFRAME 
* 
* * *     UPDATE ECS COPY OF POINTER
          LDN    0
          STD    ECSOFF 
          CALL   WRITECS,LKIN 
* 
* * *     SET NO FRAME INDICATOR IN FRBUFF
          LDN    0
          STM    FRBUFF 
          LJM    SENDFRMX 
* /---   BLOCK      FRMOVE     00 000   77/10/03  14.22 
          TITLE  MOVE FRAME 
* 
* * FRMOVE
* 
*         THIS ROUTINE IS CALLED IF -FRBUFF- IS EMPTY 
*         (FRBUFF=0).  ITS FUNCTION IS TO MOVE THE
*         NEXT FRAME FROM THE INPUT BUFFER TO -FRBUFF-. 
*         THIS CAN ONLY BE DONE WHEN THERE IS IN FACT 
*         A COMPLETE FRAME ASSEMBLED IN THE INPUT 
*         BUFFER. 
* 
 FRMOVE   SUBR
* 
* * *     IS THERE A COMPLETE FRAME IN THE -DBUFF-. 
          LDD    FRAME       OUTPUT POINTER 
          SHN    -2          DIVIDE BY FOUR CHARS/FRAME 
          STD    TT 
          LDD    ULP         NUMBER OF CHARACTERS INPUT 
          SHN    -2          DIVIDE BY FOUR 
          SBD    TT          SUBTRACT OUTPUT POINTER
          ZJN    FRMOVEX     IF NO FRAME
* 
* * *     MOVE NEXT FRAME TO -FRBUFF- 
          LDD    TT          CALCULATE WORD POSITION
          SHN    1
          STD    TT 
* 
* * *     CHECK FIRST WORD FOR NEGATIVE VALUE(START BIT)
          LDM    OSTART,TT    1ST WORD OF FRAME 
          ADC    4000B       ADD IN START BIT 
          STM    FRBUFF 
* 
* * *     GET AND CHECK SECOND WORD OF FRAME, IS IT POSITIVE
          LDM    OSTART+1,TT  SECOND WORD OF FRAME
          STM    FRBUFF+1 
* 
* * *     ADJUST OUTPUT POINTER TO NEXT FRAME POSITION
 XFR1     BSS    0
          LDD    FRAME       GET CURRENT VALUE
          ADN    CHPF        FOUR CHARACTERS/FRAME
          LPC    TMASK       MODULO 512 
          STD    FRAME       SAVE NEW VALUE 
          UJN    FRMOVEX
* /---   BLOCK      RTLINK     00 000   78/01/05  09.04 
          TITLE  REMOTE TERMINAL MODE DRIVER
* 
* * RTLINK
* 
*         THIS ROUTINE COMMUNICATES WITH PLATO AT THE SYSTEM
*         REMOTE TO THE TERMINAL.  ITS JOB IS TO GET
*         FRAMES FROM PLATO AND SEND THEM OVER THE LINK TO
*         THE SYSTEM LOCAL TO THE TERMINAL, WHILE AT THE
*         SAME TIME ACCEPTING KEYS FROM THE LINK AND
*         PUTTING THEM INTO PLATOS KEY BUFFER.
* 
 RTLINK   BSS    0
* 
* * *     MAKE SURE REMOTE IS STILL IN TOUCH
          CALL   SEST,2 
* 
* * *     SEND REQUEST REPLY
          CALL   MESSOUT
* 
* * *     SET MASK FOR IN -TMIN- AND -TMOUT-
          LDN    1
          STM    TIMK        SET TO 1, KEY INPUT
          LDN    3
          STM    TOMK        SET TO 3, FRAME OUTPUT 
* 
* * *     DO INITIALIZATIONS
          CALL   TMSTART
* 
* * *     WRITE NONZERO TO FRAMER STATUS WORD 
          LDN    77B
          STM    LKBUF+4
          LDN    1
          STD    ECS         NUMBER OF WORDS
          LDM    FRAMID      OFFSET TO CORRECT WORD 
          STD    ECSOFF 
          CALL   WRITECS,PIOSTS 
* 
* * *     CHECK IF TIME TO SEND KEY OR GET FRAME
*         WILL BE DONE APPROXIMATELY EVERY 16 MS. 
 RT0      BSS    0
          CALL   CLOCK,15 
          NJN    RT1
* 
* * *     TALK TO PLATO THROUGH ECS 
          CALL   SENDKEY     SEND KEY TO PLATO
          CALL   RCHK        SERVICE COMMUNICATION EQUIP
          CALL   GETFRAM     GET FRAME FROM PLATO 
          CALL   KYMOVE      CHECK FOR ANOTHER KEY READY
 RT1      BSS    0
          CALL   RCHK        SERVICE COMMUNITION EQUIP
* 
* * *     IS IT TIME TO CHECK FRAMAT STATUS 
          SOD    FRCHK
          NJP    RT0
* 
* * *     CHECK FOR FRAMAT RE-INITIALIZING. 
          CALL   FRMCHK 
          UJP    RT0
* /---   BLOCK      RCHK       00 000   84/11/15  11.33 
          TITLE  TERMINAL MODE IO 
* 
* * RCHK
* 
*         'CHECK COMMUNICATION EQUIPMENT TO SEE IF INPUT
*         WAITING OR READY TO SEND OUTPUT.
* 
 RCHK     SUBR
* 
* * *     CHECK FOR CHARACTER READY  AND CHARACTER REQUEST
          CALL   WCR,MCRD+MCRQ
          ZJN    RCHKX       IF NEITHER STATUS APPEARED 
          SHN    6
          PJP    RCHK1       JUMP IF CHARACTER NOT READY
* 
* * *     CHARACTER READY STATUS - PROCESS INPUT
          CALL   TMIN 
          MJN    RCHKX       IF ONLY SYNC CHARACTER 
* 
* * *     MOVE KEY TO -KEYBUFF- IF NECESSARY OR POSSIBLE
          LDM    KYBUFF 
          SHN    6
          PJN    RCHKX       IF KEY ALREADY THERE 
          CALL   KYMOVE 
          UJN    RCHKX
* 
* * *     CHECK CHARACTER READY TIME OUT
 RCHK1    BSS    0
          AOD    TIME        BUMP TIME OUT COUNTER
          ADC    -ALSEVEN    CHECK VALUE OF COUNTER 
          ZJP    LOSTC       JUMP IF TIMED OUT
* 
* * *     DO WE HAVE OUTPUT TO SEND 
          LDD    FRAME
          SBD    ULU
          ZJN    RCHKX       IF NOTHING TO OUTPUT 
* 
* * *     SEND FRAME TO REMOTE SYSTEM 
          CALL   TMOUT
          LJM    RCHKX
* /---   BLOCK      SENDKEY    00 000   77/10/03  15.43 
          TITLE  SEND KEY TO PLATO
* 
* * SENDKEY 
* 
*         WHEN A KEY HAS BEEN RECEIVED FROM THE REMOTE
*         SYSTEM THIS ROUTINE READS THE KEY BUFFER
*         CORRESPONDING TO THE TERMINAL MODE STATION
*         (TMSTAT) AND MOVES THE KEY INTO THE CORRECT 
*         BYTE.  THE PPU INDEX IS THEN INCREMENTED AND
*         THE FIRST WORD OF THE KEY BUFFER IS WRITTEN 
*         BACK TO ECS.  THE KEYS-IN BIT CORRESPONDING 
*         TO THIS STATION IS THEN SET IN THE ECS
*         KEYS-IN BUFFER (PECSIN).
* 
*         FORMAT OF KEY BUFFER';
*         / KEY / KEY / KEY / KEY / PPU INDEX / 
*         / PRESS AND TIMING KEYS / CPU INDEX / 
* 
*         INPUT PARAMETERS';
*         (KYBUFF) = KEY TO SEND  OR 7777B IF NO KEY READY
* 
 SENDKEY  SUBR
* 
* * *     CHECK FOR KEY TO SEND 
          LDM    KYBUFF 
          SHN    6
          MJN    SENDKEYX    IF NO KEY READY TO SEND
* 
* * *     CALCULATE OFFSET TO KEY BUFFER
          LDD    TMSTAT      TERMINALS STATION NUMBER 
          SHN    1           2 WORDS PER BUFFER 
          STD    ECSOFF      OFFSET TO KEY BUFFER 
* 
* * *     READ THE KEY BUFFER 
          LDN    2           NUMBER OF CM WORDS 
          STD    ECS
          CALL   READECS,PKEYECS
* 
* * *     IS THERE ROOM FOR THIS KEY
          LDM    LKBUF+4     PPU INDEX IN KEY BUFFER
          SBM    LKBUF+9     CPU INDEX IN KEY BUFFER
          ZJP    SK1         JUMP IF NO KEYS IN BUFFER
          LPN    3           MASK INDEX FOR MOD 4 
          ZJP    SK5         IGNORE KEYS NO ROOM
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   RCHK 
* 
* * *     BUMP PPU INDEX TO DETERMINE WHERE NEXT KEY GOES 
 SK1      BSS    0
          AOM    LKBUF+4     INCREMENT PPU INDEX
          LPN    3           MASK TO FIND BYTE INDEX
          STD    D0          SAVE INDEX 
          LDM    KYBUFF      GET NEW KEY
          STM    LKBUF,D0    PLUG IN NEW KEY
* 
* * *     WRITE KEY BUFFER BACK TO ECS
          LDN    1           NUMBER OF CM WORDS 
          STD    ECS
          CALL   WRITECS,PKEYECS
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   RCHK 
* /---   BLOCK      SENDKEY    00 000   77/10/03  15.44 
* 
* * *     COMPUTE INDEX FOR THIS STATION IN KEYS-IN BIT TAB.
          LDD    TMSTAT 
          SHN    18-5        DIVIDE BY 32 
          STD    ECSOFF      SAVE WORD OFFSET 
          SHN    5
          LPN    37B         MASK FOR STATION NUMBER
          ADN    4           ADD BIAS TO STARTING BIT 
          STD    T1 
* 
* * *     COMPUTE BYTE AND BIT POSITION IN THAT BYTE
          LDN    3
          STD    SENDI       BYTES 1-3 HAVE KEYS-IN BITS
 SK2      BSS    0
          LDD    T1 
          SBN    12 
          MJP    SK3         JUMP IF IN THIS BYTE 
          STD    T1 
          SOD    SENDI       DECREMENT BYTE POINTER 
          UJP    SK2
* 
* * *     SET UP SHIFT INSTRUCTION TO POSITION BIT
 SK3      BSS    0
          LDM    SKSHF
          LPC    -77B        MASK OFF OLD SHIFT COUNT 
          ADD    T1          ADD IN NEW SHIFT COUNT 
          STM    SKSHF
* 
* * *     POSITION BIT MASK AND SET UP MASKING INSTRUCTIONS 
          LDN    1
 SKSHF    BSS    0
          SHN    0           POSITION BIT WITHIN BYTE 
          STM    SKAND       LOGICAL PRODUCT INSTRUCTION
          STM    SKXOR       LOGICAL DIFFERENCE INSTRUCTION 
* 
* * *     READ KEYS-IN WORD  ( 1 WORD)
          CALL   READECS,PECSIN 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   RCHK 
* 
* * *     CHECK FOR BIT ALREADY SET 
 SK4      BSS    0
          LDM    LKBUF,SENDI
          LPC    0           MASK BIT 
 SKAND    EQU    *-1
          NJP    SK5         EXIT IF ALREADY SET
* 
* * *     SET BIT 
          LDM    LKBUF,SENDI
          LMC    0
 SKXOR    EQU    *-1
          STM    LKBUF,SENDI
* 
* * *     MARK LOWEST BYTE FOR REREAD 
          LDM    FRAMID 
          STM    LKBUF+4
* 
* * *     WRITE BACK TO ECS 
          CALL   WRITECS,PECSIN 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   RCHK 
* 
* * *     READ BACK AND CHECK FOR CPU CONFLICT
          CALL   READECS,PECSIN 
          LDM    LKBUF+4
          SBM    FRAMID 
          NJP    SK4         JUMP IF CONFLICT OCCURRED
* 
* * *     INITIALIZE KYBUFF 
 SK5      BSS    0
          LDC    7777B
          STM    KYBUFF 
          LJM    SENDKEYX 
* /---   BLOCK      GETFRAM    00 000   77/10/03  15.45 
          TITLE  GET FRAMES FROM ECS
* 
* * GETFRAM 
* 
*         WHEN A STATION IS USING TERMINAL MODE THE 
*         FRAMER DIRECTS ALL OF ITS OUTPUT TO A SPECIAL 
*         SET OF FRAMES.  EACH FRAME IN THIS BUFFER (LFRBUF)
*         IS 4 WORDS LONG AND HAS A CORRESPONDING 
*         ENTRY IN ASSOCIATED TABLE (LFRLTHS) WHICH GIVES 
*         THE NUMBER OF TERMINAL FRAMES IN THE FRAME
*         WAITING TO BE OUTPUT.  THE LINK DRIVER MARKS
*         THE FRAME THAT IT WILL LOOK AT NEXT BY
*         INCREMENTING LFRPNT.  THE BOTTOM SEVEN BITS 
*         OF THIS POINTER ARE THE FRAME INDEX.  THIS
*         ROUTINE MOVES THE TERMINAL FRAMES FROM
*         THE FRAME BUFFER INTO THE LINK DRIVER OUTPUT
*         BUFFER FOR LATER TRANSMISSION.
* 
* 
 GETFRAM  SUBR
* 
* * *     SAVE CURRENT FRAME POINTER
          LDM    IFRAME+4 
          STM    IFRAMEX
* 
* * *     BUMP PPU FRAME POINTER, ALSO MOVES TO LKBUF 
          CALL   AFIVE,IFRAME 
* 
* * *     WRITE IT TO ECS 
          LDN    0
          STD    ECSOFF 
          LDN    1
          STD    ECS         NUMBER OF WORDS TO WRITE 
          CALL   WRITECS,LFRPNT 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   RCHK 
* /---   BLOCK      GETFRAM    00 000   77/10/03  15.45 
* 
* * *     ISOLATE FRAME INDEX 
          LDM    IFRAMEX
          LPC    177B        128 FRAMES 
          STD    ECSOFF 
* 
* * *     READ FRAME LENGTH 
          CALL   READECS,LFRLTHS
          LDM    LKBUF+4
          ZJN    GETFRAMX    IF FRAME IS EMPTY
          STD    ECS         SAVE FRAME COUNT 
* 
* * *     SERVICE COMMUNICATION EQUIPMENT 
          CALL   RCHK 
* 
* * *     CALCULATE OFFSET OF FRAME IN FRAME BUFFER 
          LDD    ECSOFF      FRAME NUMBER 
          SHN    2           4 WORDS PER FRAME
          STD    ECSOFF 
* 
* * *     READ FRAME FROM ECS 
          CALL   READECS,LFRBUF 
* 
* * *     CALCULATE POSITION OF LAST FRAME IN LKBUF 
*         (NEW ECS) = ((OLD ECS)-1)*5 
          LDD    ECS         NUMBER OF FRAMES 
          SBN    1           ADJUST SO 1 EQUALS ZERO OFFSET 
          STD    ECS         SAVE NO. OF FRAMES - 1 
          SHN    2           MULTIPLE BY 4
          RAD    ECS
* 
* * *     MOVE NEW FRAME TO OUTPUT BUFFER 
          LDD    FRAME       LOAD CHARACTER POSITION
          SHN    -1          DIVIDE BY TWO, WORD POSITION 
          STD    TT          SAVE 
          LDM    LKBUF,ECS   GET 1ST BYTE OF FRAME
          STM    ISTART,TT   MOVE TO OUTPUT BUFFER. 
          LDM    LKBUF+1,ECS  GET 2ND BYTE OF FRAME 
          STM    ISTART+1,TT  MOVE IT TO THE OUTPUT BUFFER
* 
* * *     MOVE POINTER TO NEXT AVAILABLE SPOT.
          LDD    FRAME       GET POINTER
          ADN    CHPF        FOUR CHARACTERS/FRAME
          LPC    TMASK       KEEP MOD 128 
          STD    FRAME
          LJM    GETFRAMX 
* 
* /---   BLOCK      KYMOVE     00 000   77/10/03  14.22 
          TITLE  MOVE KEY 
* 
* * KYMOVE
* 
*         THIS ROUTINE IS CALLED IF -KYBUFF- IS EMPTY 
*         (KYBUFF=4XXX).  ITS FUNCTION IS TO MOVE THE 
*         NEXT KEY FROM THE INPUT BUFFER TO -KYBUFF-. 
*         THIS CAN ONLY BE DONE WHEN THERE IS IN FACT 
*         A COMPLETE KEY ASSEMBLED IN THE INPUT 
*         BUFFER. 
* 
 KYMOVE   SUBR
* 
* * *     IS THERE A COMPLETE KEY IN THE -DBUFF-. 
          LDD    KEY         OUTPUT POINTER 
          SHN    -1          DIVIDE BY TWO CHARS/FRAME
          STD    TT 
          LDD    ULP         NUMBER OF CHARACTERS INPUT 
          SHN    -1          DIVIDE BY TWO
          SBD    TT          SUBTRACT OUTPUT POINTER
          ZJN    KYMOVEX     IF NO KEY
* 
* * *     MOVE NEXT KEY TO -KYBUFF- 
          LDM    OSTART,TT    GET NEW KEY 
          STM    KYBUFF 
* 
* * *     ADJUST OUTPUT POINTER TO NEXT FRAME POSITION
          LDD    KEY         GET CURRENT VALUE
          ADN    CHPK        TWO CHARACTERS/FRAME 
          LPC    TMASK       MOD 512
          STD    KEY         SAVE NEW VALUE 
          UJN    KYMOVEX
* /---   BLOCK      TMSTART    00 000   78/01/04  21.48 
          EJECT 
* 
* * TMSTART 
* 
 TMSTART  SUBR
* 
* * *     SET MODE TO TERMINAL MODE AND STATUS COUNT
          LDN    1
          STD    MODE 
          STD    NC 
* 
* * *     INITIALIZE PACKING AND UNPACKING VARIABLES
          LDN    0
          STD    WP 
          STD    WU 
          STD    ULU
          STD    ULP
          STD    KEY
          STD    FRAME
          STD    TIME 
          STD    CLK
          STM    CLKU 
          STM    CLKL 
          LDC    ALSEVEN
          STD    NW 
* 
* * *     SET TERMINAL MODE STATION.
          LDM    XTMSTAT
          STD    TMSTAT 
* 
* * *     SET FRAM ID NUMBER
          LDM    XFRAMID
          STM    FRAMID 
* 
* * *     SAVE NO. OF TERMINAL WORDS IN FRAME 
          LDM    XLFRLTH
          STM    LFRLTH 
* 
* * *     SET -FORINIP- ECS ADDRESS 
          LDM    ECL         LOWER ECS RA 
          ADC    XFORINIP    ADD RELATIVE ADDRESS 
          STM    FORINIP+1
          SHN    -12
          ADM    ECU         ADD IN UPPER ECS RA
          STM    FORINIP
* 
* * *     SET UP ECS ADDRESS TABLE
          LDN    0
          STD    T1          POINTER TO ADDRESS TABLE 
          STD    T2          POINTER TO INPUT BUFFER
 TMS1     BSS    0
          LDM    XPKEYEC+1,T2  LOWER 12 BITS OF ECS ADDRESS 
          ADM    ECL         LOWER 12 BITS OF ECS RA
          STM    ECSAD+1,T1 
          SHN    -12
          ADM    ECU         UPPER 9 BITS OF ECS RA 
          ADM    XPKEYEC,T2  UPPER 9 BITS OF ECS ADDRESS
          STM    ECSAD,T1 
          LDN    5
          RAD    T2          BUMP POINTER TO INPUT BUFFER 
          LDN    2
          RAD    T1          BUMP POINTER TO ADDRESS TABLE
          SBN    ECSLTH      SUBTRACT LENGTH OF TABLE 
          MJN    TMS1        JUMP IF MORE TO DO 
* 
* * *     CLEAR IN/OUT POINTERS FOR LINK TO FRAMER BUFFER 
          CALL   LCLEAR,10   CLEAR FIRST 10 BYTES OF LKBUF
          LDN    2
          STD    ECS         WRITE 2 CM WORDS 
          LDN    0
          STD    ECSOFF      NO OFFSET
          CALL   WRITECS,LKIN  CLEAR POINTERS 
* 
* * *     INITIALIZE LOCAL FRAME POINTER
          LDN    1
          STD    ECS         TRANSFER 1 WORD
          CALL   READECS,LFRPNT 
* 
* * *     MOVE FRAME POINTER TO LOCAL BUFFER
          LDN    4
          STD    T1 
 TMS3     BSS    0
          LDM    LKBUF,T1 
          STM    IFRAME,T1
          SOD    T1 
          PJN    TMS3        JUMP IF MORE TO MOVE 
          LJM    TMSTARTX 
* /---   BLOCK      TMIN       00 000   77/08/17  14.05 
          TITLE  TERMINAL MODE INPUT-OUTPUT 
* 
* * TMIN
* 
*         THIS ROUTINE PROCESSES INPUT FROM THE 311 AND 
*         PACKS IT INTO -XBUFF-.  IF THIS SYSTEM IS 
*         THE REMOTE SYSTEM INPUT WILL BE KEYS, WHILE 
*         A LOCAL SYSTEM WILL INPUT OUTPUT FRAMES.
*         EXIT PARAMETERS 
*         (A) WITH BE NEGATIVE IF CHARACTER WAS SYNC CODE.
*         (A) WITH BE POSITIVE IF ANY OTHER CHARACTER.
* 
 TMIN     SUBR
          LDN    0
          STD    TIME        CLEAR TIMEOUT COUNTER
* 
* * *     PROCESS INPUT 
          CALL   GETCHR 
          MJN    TMINX       IF SYNC CODE 
* 
* * *     CHECK OUT OF SEQUENCE 
          LDD    ULP
          LPC    1           THIS MASK IS SET TO 1 OR 3 BY
 TIMK     EQU    *-1           -TLSET- OR -RTLSET-. 
          ADN    3           SET BIT 2 IF 1, 2 OR 3 
          SHN    3           POSITION START BIT MASK
          LMD    CHAR        MASK CHARACTER 
          SHN    12          WAS BIT CORRECT
          PJN    TMINX
* 
* * *     CHECK WHERE IN BYTE THIS CHARACTER SHOULD GO
 TM1      BSS    0
          AOD    ULP
          LPN    1
          ZJN    TM2         JUMP IF LOWER CHARACTER
          AOD    WP          ADVANCE WORD POINTER.
* 
* * *     PUT NEW CHAR. INTO UPPER CHAR. POSITION 
          LDD    CHAR 
          LPN    37B
          SHN    5
          STM    OSTART-1,WP STORE IN BUFFER
          UJN    TM3
* 
* * *     STORE NEW CHAR. IN LOWER CHAR. POSITION 
 TM2      BSS    0
          LDD    CHAR 
          LPN    37B
          RAM    OSTART-1,WP  STORE INTO BUFFER 
* 
* * *     HAVE WE REACHED THE END OF THE BUFFER 
 TM3      BSS    0
          LDD    ULP
          LPC    TMASK
          NJN    TM4         IF STILL ROOM
          STD    WP          OTHERWISE START AT BEGINNING 
          STD    ULP
 TM4      LJM    TMINX
* /---   BLOCK      TMOUT      00 000   76/06/11  15.52 
          EJECT 
* 
* * TMOUT 
* 
*         THIS ROUTINE HANDLES 311 OUTPUT DURING TERMINAL 
*         MODE OPERATION.  THE OUTPUT WILL BE KEYS IF AT
*         THE LOCAL SYSTEM, WHILE FRAMES WILL BE OUTPUT 
*         IF AT THE REMOTE SYSTEM.  THE DATA IS UNPACKED
*         FROM -DBUFF- AND SENT 6 BITS AT A TIME. 
* 
 TMOUT    SUBR
* 
* * *     IS NEXT CHAR. TO BE TAKEN FROM UPPER OR LOWER 
          AOD    ULU
          LPN    1
          ZJN    TO1         JUMP IF LOWER
* 
* * *     BUMP TO NEXT WORD IN BUFFER.
          AOD    WU 
* 
* * *     ISOLATE UPPER 5 BITS. 
          LDM    ISTART-1,WU
          SHN    13 
          UJN    TO2
* 
* * *     GET LOWER FIVE BITS IN WORD 
 TO1      BSS    0
          LDM    ISTART-1,WU
* 
* * *     ISOLATE FIVE BIT PACKAGE
 TO2      BSS    0
          LPN    37B
          ADC    DCON 
          STD    OC 
* 
* * *     ADD START BIT IF STARTING CHAR. OF FRAME OR KEY 
          LDD    ULU
          SBN    1
          LPC    1           'THIS MASK SET TO 1 OR 3 BY
 TOMK     EQU    *-1          -TLSET- OR -RTLSET-.
          NJN    TO3
* 
* * *     ADD START BIT 
          LDN    40B
          RAD    OC 
* 
* * *     SEND THIS CHARACTER 
 TO3      BSS    0
          LDM    PARTBLE,OC  GET PARITY BIT 
          CALL   OCHR 
* 
* * *     IF AT END OF BUFFER SET POINTER TO BEGINNING
          LDD    ULU
          LPC    TMASK       MODULO 1024
          NJN    TO4         IF NOT AT END
          STD    WU          RESET POINTER TO FIRST WORD. 
          STD    ULU
 TO4      LJM    TMOUTX 
* /---   BLOCK      READECS    00 000   77/08/29  15.26 
          TITLE  READ ECS 
* 
* * READECS 
* 
*         READ ECS USING CPU MONITOR CALL, WHICH TRANSFERS
*         DATA TO CM (TRNBF) WHERE THE PPU CAN THEN READ IT.
* 
*         INPUT PARAMETERS';
*         (A) - POINTER TO ECS ADDRESS
*         (ECS) - NUMBER OF CM WORDS (1-60D)
*         (ECSOFF) - OFFSET TO ADD TO BASE ECS ADDRESS
* 
*         OUTPUT PARAMETERS'; 
*         (LKBUF) - DATA READ FROM ECS
*         (A) = ZERO - TRANSFER OKAY
*             = NONZERO - ECS ERROR 
* 
* 
 READECS  SUBR
* 
* * *     SAVE ADDRESS OF ECS ADDRESS 
          STD    TT 
* 
          LDK    ZERL        (A) = CM ADDR OF ZERO WORD 
          CRD    CM          CLEAR LIST ENTRY 
          LDM    1,TT        LOWER 12 BITS OF ADDRESS 
          ADD    ECSOFF      ADD OFFSET 
          STD    CM+4 
          SHN    -12         SAVE ADD OVERFLOW
          ADM    0,TT        UPPER 9 BITS OF ADDRESS
          STD    CM+3 
 .NOSV2   IFLT   OSLEV,562D  IF NOS V1
          LDD    MA 
          CWD    CM          (MB) = 36/TRASH,24/EM ADDRESS
* 
* * *     PUT SUBFUNCTION AND R/W CODES INTO REQUEST
          LDN    0
          STD    CM+4        (CM+4) = R/W CODE (READ) 
          LDC    /CPS/RWEM*1000B
          STD    CM+3        (CM+3) = SUBFUNCTION = *RWEM*
* 
* * *     PUT CM ADDRESS AND NO. OF WORDS INTO REQUEST
          LOADCM TRNBF       GET CM ADDRESS 
          STD    CM+2        STORE LOWER 12 BITS
          SHN    -12         POSITION TOP 6 BITS
          STD    CM+1 
          LDD    ECS         NO. OF WORDS MINUS ONE 
          SBN    1           ADJUST COUNT FOR THIS REQUEST
          SHN    6
          RAD    CM+1        ADD TO REQUEST 
 .NOSV2   ELSE               IF NOS V2
          LDD    ECS         (A) = NUM OF CPU WORDS TO READ 
          SHN    6
          STD    CM+1        (CM+1) = CPU WORDS TO READ 
          LOADCM TRNBF       (A) = CM ADDRESS OF LIST 
          CWD    CM          UPDATE LIST (1 ENTRY)
 
          LDK    ZERL        (A) = CM ADDR OF ZERO WORD 
          CRD    CM          CLEAR REQUEST WORD 
          LDN    1           (A) = ONE LIST ENTRY TO PROCESS
          SHN    6
          STD    CM+1        (CM+1) = NUMBER OF LIST ENTRIES
          LOADCM TRNBF       (A) = CM ADDRESS OF LIST 
          STD    CM+2        (CM+2) = LOWER PART OF LIST ADR
          SHN    -12D        POSITION UPPER PART OF LIST ADR
          LPN    77B         (A) = UPPER PART W/OUT SIGN EXT
          RAD    CM+1        (CM+1) NOW INCLUDES UPPER PART 
 
*         SET THE SUBFUNCTION (*PELS*), READ EM, AND
*         ABSOLUTE SYSTEM EM ADDRESS. 
 
          LDK    /CPS/PELS*1000B  (A) = SUBFUNCTION = *PELS*
          STD    CM+3 
 .NOSV2   ENDIF 
* 
* * *     READ ECS TO CM
          MONITOR ECSM       READ ECS TO CM 
          LDD    CM+1 
* /---   BLOCK      READECS    00 000   84/11/15  11.34 
          NJP    READECSX    IF EM ERROR
* 
* * *     READ CM TO PPU
          LOADCM TRNBF       CM LOCATION OF DATA
 .NOSV2   IFGE   OSLEV,562D  IF NOS V2
          ADN    1           SKIP THE LIST
 .NOSV2   ENDIF 
          CRM    LKBUF,ECS
          LDN    0
          LJM    READECSX 
* /---   BLOCK      WRITECS    00 000   77/08/29  15.27 
          TITLE  WRITE ECS
* 
* * WRITECS 
* 
*         WRITE ECS USING CPU MONITOR CALL.  THE DATA 
*         IS TRANSFERRED TO A CM BUFFER (TRNBF) BY THE
*         PPU, THEN TO ECS USING THE MONITOR CALL.
* 
*         INPUT PARAMETERS';
*         (A) - POINTER TO ECS ADDRESS
*         (ECS) - NUMBER OF CM WORDS (1-64) 
*         (ECSOFF) - OFFSET TO ADD TO BASE ECS ADDRESS
*         (LKBUF) - DATA TO BE WRITTEN
* 
*         OUTPUT PARAMETERS'; 
*         (A) = ZERO - TRANSFER OKAY
*             = NONZERO - ECS ERROR 
* 
*         MONITOR REQUEST FORMAT
*         / REQUEST CODE / NNCC / CCCC / REEE / EEEE/ 
*         N - NUMBER OF CM WORDS MINUS ONE. 
*         C - CM BUFFER ADDRESS 
*         R - READ/WRITE CODE (READ = 2, WRITE = 3) 
*         E - ECS ADDRESS 
* 
* 
 WRITECS  SUBR
* 
* * *     SAVE ADDRESS OF ECS ADDRESS 
          STD    TT 
* * *     PUT ECS ADDRESS INTO REQUEST
          LDK    ZERL        (A) = CM ADDR OF ZERO WORD 
          CRD    CM          CLEAR LIST ENTRY 
          LDM    1,TT        LOWER 12 BITS OF ADDRESS 
          ADD    ECSOFF      ADD OFFSET 
          STD    CM+4 
          SHN    -12         SAVE ADD OVERFLOW
          ADM    0,TT        UPPER 9 BITS OF ADDRESS
          STD    CM+3 
 .NOSV2   IFLT   OSLEV,562D  IF NOS V1
          LDD    MA 
          CWD    CM          (MB) = 36/TRASH,24/EM ADDRESS
* 
* * *     PUT SUBFUNCTION AND R/W CODES INTO REQUEST
          LDN    1
          STD    CM+4        (CM+4) = R/W CODE (WRITE)
          LDC    /CPS/RWEM*1000B
          STD    CM+3        (CM+3) = SUBFUNCTION = *RWEM*
* 
* * *     PUT CM ADDRESS AND NO. OF WORDS INTO REQUEST
          LOADCM TRNBF       GET CM ADDRESS 
          STD    CM+2        STORE LOWER 12 BITS
          SHN    -12         POSITION TOP 6 BITS
          STD    CM+1 
          LDD    ECS         NO. OF WORDS 
          SBN    1           ADJUST COUNT FOR THIS REQUEST
          SHN    6
          RAD    CM+1        ADD TO REQUEST 
 .NOSV2   ELSE               IF NOS V2
          LDD    ECS         (A) = NUM OF CPU WORDS TO READ 
          SHN    6
          STD    CM+1        (CM+1) = CPU WORDS TO READ 
          LOADCM TRNBF       (A) = CM ADDRESS OF LIST 
          CWD    CM          UPDATE LIST (1 ENTRY)
 
          LDK    ZERL        (A) = CM ADDR OF ZERO WORD 
          CRD    CM          CLEAR REQUEST WORD 
          LDN    1           (A) = ONE LIST ENTRY TO PROCESS
          SHN    6
          STD    CM+1        (CM+1) = NUMBER OF LIST ENTRIES
          LOADCM TRNBF       (A) = CM ADDRESS OF LIST 
          STD    CM+2        (CM+2) = LOWER PART OF LIST ADR
          SHN    -12D        POSITION UPPER PART OF LIST ADR
          LPN    77B         (A) = UPPER PART W/OUT SIGN EXT
          RAD    CM+1        (CM+1) NOW INCLUDES UPPER PART 
 
* /---   BLOCK      WRITECS    00 000   77/08/29  15.27 
*         SET THE SUBFUNCTION (*PELS*), WRITE EM, AND 
*         ABSOLUTE SYSTEM EM ADDRESS. 
 
          LDK    /CPS/PELS*1000B+1S8 (A) = *PELS* + WRITE EM
          STD    CM+3        (CM+3) = SUBFUNCTION 
 .NOSV2   ENDIF 
* 
* * *     WRITE PPU TO CM BUFFER
          LOADCM TRNBF       CM LOCATION OF DATA
 .NOSV2   IFGE   OSLEV,562D  IF NOS V2
          ADN    1           SKIP THE LIST
 .NOSV2   ENDIF 
          CWM    LKBUF,ECS
* 
* * *     WRITE FROM CM TO ECS
          MONITOR ECSM       READ ECS TO CM 
          LDD    CM+1 
          LJM    WRITECSX 
* /---   BLOCK      CLOCK      00 000   77/08/26  16.41 
          TITLE  CLOCK
* 
* * CLOCK 
* 
*         UPDATES RUNNING CLOCK IN CLKU AND CLKL
*         THIS ROUTINE MUST BE DONE AT LEAST ONCE EVERY 
*         4 MILLISECONDS. 
* 
*         INPUT PARAMETERS';
*         (A) = NUMBER OF MILLISECONDS AT WHICH TO TIME OUT 
* 
*         OUTPUT PARAMETERS'; 
*         (A) - NONZERO HAVE NOT REACH TIME OUT TIME
*               ZERO TIME OUT TIME HAS BEEN REACHED 
* 
 CLOCK    SUBR
          STD    TT          SAVE INPUT PARAMETE
* 
* * *     READ MICROSECOND CLOCK
          IAN    14B
* 
* * *     SAVE NEW INFO AND COMPARE TO LAST READING 
          STD    D0 
          SBD    CLK         LAST READING 
          PJN    CLOCK1      JUMP IF NO WRAP AROUND 
* 
* * *     CLOCK HAS WRAPPED AROUND RECALCULATE DIFFERENCE 
          ADC    10000B 
* 
* * *     UPDATE RUNNING TIME 
CLOCK1    BSS    0
          SHN    2           ADJUST TO GET MS IN UPPER CELL 
          RAM    CLKL        LOWER 12 BITS OF CLOCK 
          SHN    -12
          RAM    CLKU        UPPER 12 BITS
* 
* * *     REPLACE OLD CLOCK READING WITH NEW ONE
          LDD    D0 
          STD    CLK
* 
* * *     IS IT TIME TO TIME OUT
          LDM    CLKU 
          SBD    TT 
          MJN    CLOCKX 
* 
* * *     TIME OUT -- CLEAR THE CLOCK 
          LDN    0
          STM    CLKU 
          STM    CLKL 
          UJN    CLOCKX 
* /---   BLOCK      READCM     00 000   77/08/17  09.26 
          TITLE  READ AND CLEAR PPU COMMUNICATIONS SWITCH 
*         READSW
* 
*            THIS ROUTINE READS THE SWITCH FROM THE 
*         CM COMUNICATIONS BUFFER AND SAVES THE LAST BYTE 
*         IN -A-. 
* 
 READSW1  LDD    CM+4 
 
 READSW   SUBR
          LOADCM COMBF       PRESET TO 1ST WORD OF CM 
*                            COMMUNICATION BUFFER.
          CRD    CM          READ OUTPUT DATA REQUEST SWITCH
          LDD    CM+4 
          ADC    -MAXCM      IS READ TOO LARGE
          MJN    READSW1     IF READ LENGTH OK
          CALL   SERROR,SCML
          SPACE  4
*         READ
* 
*            THIS ROUTINE READS THE REQUEST PARAMETERS
*         FROM THE PARAMETER SECTION OF THE CM
*         COMMUNICATION BUFFER TO -IBF- AND THE DATA
*         PORTION TO -IHDR-.
* 
 READ     SUBR
 READ1    LOADCM COMBF       PRESET TO 1ST WORD OF CM 
*                            COMMUNICATION BUFFER.
          ADN    PPOS        ADJUST TO PARAMETER SECTION. 
          CRM    IBF,LT      READ INTO PPU
* 
* * *     MOVE NEW PARAMETER SECTION TO OUTPUT BUFFER.
* 
          LDN    IHDR-IBF-1  BYTES TO MOVE. 
          STD    D0 
 READ2    BSS    0
          LDM    IBF,D0 
          STM    OBF,D0 
          SOD    D0 
          PJP    READ2       JUMP IF NOT FINISHED.
          UJN    READX
* /---   BLOCK      WRITE      00 000   77/08/17  15.04 
          TITLE  WRITE TO CM BUFFER.
*         WRITE 
* 
*         THIS ROUTINE WRITES DATA RECEIVED OVER
*         LINK, PLUS ANY ERROR CODES OR STATUS TO A 
*         CM BUFFER.
*         THE TOP BIT OF THE SWITCH IS SET TO 1 AND THE 
*         NEXT-TO-LAST BYTE IS SET TO THE NUMBER OF CM
*         WORDS IN THIS RESPONSE. 
* 
*         INPUT PARAMETER 
*         (DL) = NUMBER OF CM WORDS OF DATA 
* 
* 
 WRITE    SUBR
 WTE1     BSS    0
          LDN    PLTH        LENGTH OF PARAMETER SECTION. 
          ADD    DL          PLUS NUMBER OF DATA WORDS. 
          STD    D0 
 WRITE1   LOADCM COMBF       PRESET TO 1ST WORD OF CM 
*                            COMMUNICATION BUFFER.
          ADN    PPOS        ADJUST TO PARAMETER SECTION. 
          CWM    OBF,D0      WRITE TO CM. 
          LDN    ZERL        CLEAR BUFFER 
          CRD    CM 
          LDC    4000B       SIGN BIT SET 
          STD    CM 
          LDD    D0 
          STD    CM+3        SET NO. OF RESPONSE WORDS. 
 WRITE2   LOADCM COMBF       PRESET TO 1ST WORD ADDRESS OF
*                            PARAMETER BUFFER IN CM.
          CWD    CM          WRITE SWITCH 
          LDN    0
          STD    DL          CLEAR DATA WORD COUNT
* 
* * *     PRESS KEY ON LESSON TO INDICATE REQUEST IS DONE.
          LDC    LAB1K       LAB1 TO BE PRESSED 
          STM    RQKEY
          CALL   PREQ,PKEY
          UJN    WRITEX 
* /---   BLOCK      I/O CHAR   00 000   78/01/22  17.15 
          TITLE CHARACTER I/O 
* 
* * ICHR
* 
*         THIS ROUTINE INPUTS ONE BYTE OF INFORMATION 
*         FROM THE EVEN CHANNEL OF THE 311. 
* 
 ICHR     SUBR
          RJM    CCR
          NJN    ICHR1       IF EQUIP/CHANNEL RESERVED
          CALL   SERROR,SENA
 
 ICHR1    BSS    0
          PORT   EVEN 
          FNC    DCIC,C=CH   SELECT 6681 INPUT
          ACN    C=CH,40B    ACTIVATE THE CHANNEL 
          WAIT   FULL,C=CH,ICHR10 
          IAN    C=CH,40B    INPUT BYTE OF DATA 
          DCN    C=CH,40B    DE-ACTIVATE THE CHANNEL
          UJN    ICHRX
* 
 ICHR10   CALL   CTIMEO      PROCESS CHANNEL TIME-OUT 
          UJN    ICHRX
          SPACE  4
* 
* * OCHR
* 
*         THIS ROUTINE OUTPUTS ONE BYTE OF INFORMATION
*         TO THE EVEN CHANNEL OF THE 311. 
* 
 OCHR     SUBR
          STD    T1          SAVE (A) 
          RJM    CCR
          NJN    OCHR1       IF EQUIP/CHANNEL RESERVED
          CALL   SERROR,SENA
 
 OCHR1    LDD    T1          RESTORE (A)
          PORT   EVEN 
          FNC    DCOC,C=CH   SELECT 6681 OUTPUT 
          ACN    C=CH,40B    ACTIVATE THE CHANNEL 
          OAN    C=CH,40B    OUTPUT DATA
          WAIT   EMPTY,C=CH,OCHR10
          DCN    C=CH,40B    DE-ACTIVATE THE CHANNEL
          UJN    OCHRX
* 
 OCHR10   CALL   CTIMEO      PROCESS CHANNEL TIME-OUT 
          UJN    OCHRX
* /---   BLOCK      I/O CHAR   00 000   78/01/22  18.41 
          EJECT 
* 
* * ICHR2 
* 
*         THIS ROUTINE INPUTS ONE BYTE OF INFORMATION 
*         FROM THE ODD CHANNEL OF THE 311.
* 
 ICHR2    SUBR
          RJM    CCR
          NJN    ICHR3       IF EQUIP/CHANNEL RESERVED
          CALL   SERROR,SENA
 
 ICHR3    BSS    0
          PORT   ODD
          FNC    DCIC,C=CH   SELECT 6681 INPUT
          ACN    C=CH,40B    ACTIVATE THE CHANNEL 
          WAIT   FULL,C=CH,ICHR20 
          IAN    C=CH,40B    INPUT BYTE OF DATA 
          DCN    C=CH,40B    DE-ACTIVATE THE CHANNEL
          STD    PS          SAVE STATUS
          UJN    ICHR21 
* 
 ICHR20   CALL   CTIMEO      PROCESS CHANNEL TIME-OUT 
 ICHR21   UJN    ICHR2X 
          SPACE  4
* 
* * OCHR2 
* 
*         THIS ROUTINE OUTPUTS ONE BYTE OF INFORMATION
*         TO THE ODD CHANNEL OF THE 311.
* 
 OCHR2    SUBR
          STD    T1          SAVE (A) 
          RJM    CCR
          NJN    OCHR3       IF EQUIP/CHANNEL RESERVED
          CALL   SERROR,SENA
 
 OCHR3    LDD    T1          RESTORE (A)
          PORT   ODD
          FNC    DCOC,C=CH   SELECT 6681 OUTPUT 
          ACN    C=CH,40B    ACTIVATE THE CHANNEL 
          OAN    C=CH,40B    OUTPUT DATA
          WAIT   EMPTY,C=CH,OCHR20
          DCN    C=CH,40B    DE-ACTIVATE THE CHANNEL
          UJN    OCHR21 
* 
 OCHR20   CALL   CTIMEO      PROCESS CHANNEL TIME-OUT 
 OCHR21   UJN    OCHR2X 
          SPACE  4
* 
* * CTIMEO
* 
*         THIS ROUTINE ISSUES A DAYFILE MESSAGE FOR A 
*         CHANNEL TIME-OUT AND DROPS THE PPU IF THE PPU IS
*         NOT ALREADY IN THE PROCESS OF DROPPING. 
* 
 CTIMEO   SUBR
          CALL   DFM,CTOMSG  OUTPUT TIME-OUT MESSAGE
          LDM    DPPF        CHECK IF ALREADY DROPPING PPU
          NJN    CTIMEOX
          UJP    DPP
* 
 CTOMSG   DIS    ,*(CLD) CHANNEL TIME-OUT*
* 
          SPACE  3
* 
* * CCR 
* 
*         THIS ROUTINE CHECKS IF THE 3266 EQUIPMENT AND 
*         CHANNEL HAVE BEEN RESERVED BEFORE ATTEMPTING TO 
*         DO ANYTHING WITH IT.  ON EXIT, (A) = 0 IF EITHER
*         THE EQUIPMENT OR CHANNEL IS NOT RESERVED, NON-
*         ZERO OTHERWISE. 
* 
 CCR      SUBR
          LDC    ALSEVEN
          LMM    CLEQ 
          ZJN    CCRX        IF EQUIPMENT NOT RESERVED
          LDC    ALSEVEN
          LMM    CLCH 
          ZJN    CCRX        IF CHANNEL NOT RESERVED
          LDN    1
          UJN    CCRX 
* /---   BLOCK      WCR        00 000   76/05/13  14.23 
          TITLE  WAIT CHARACTER READY OR REQUEST
* 
* * WCR 
* 
*         THIS ROUTINE WAITS FOR THE SPECIFIED STATUS 
*         TO APPEAR OR UNTIL IT HAS CHECK THE STATUS
*         THE SPECIFIED NUMBER OF TIMES.
* 
*         INPUT PARAMETERS
*         (A) = MASK FOR REQUIRED STATUS
*         (NC) = NUMBER OF STATUS CHECKS TO BE PERFORMED. 
* 
*         OUTPUT PARAMETERS 
*         (A) = 0 STATUS DID NOT APPEAR.
*               1 INDICATED STATUS APPEARED 
*         (CHAR) = INPUT BYTE 
* 
 WCR      SUBR
* 
* * *     SAVE SPECIFIED MASK 
          STM    WRM
* 
* * *     GET NUMBER OF TIMES TO CHECK
          LDD    NC 
          STD    D0 
* 
* * *     CHECK IF TIME TO CHECK FOR STORAGE RELOCATION 
 WR1      BSS    0
          SOD    TI 
          NJN    WR2         JUMP IF NOT TIME TO CHECK
          RJM    PAUSE       CHECK FOR STORAGE RELOCATION 
          RJM    DROPCHK     CHECK FOR DROP SIGNAL
* 
* * *     INPUT STATUS
 WR2      BSS    0
          RJM    ICHR 
          STD    CHAR        SAVE INPUT 
* 
* * *     CHECK FOR SPECIFIED STATUS
          LPC    *
 WRM      EQU    *-1
          NJN    WCRX        IF STATUS APPEARED 
* 
* * *     STATUS CHECK DONE, IF SO CHECK ODD CHANNEL STATUS 
          SOD    D0 
          NJN    WR1         JUMP IF NOT
* 
* * *     IF TERMINAL MODE, DO TIME OUT CHECK 
          LDD    MODE 
          ZJN    WCRX        IF DATA MODE 
          AOD    TIME        NUMBER OF CHECKS MADE FOR INPUT
          ADC    -ALSEVEN    MAXIMUM CHECKS TO MAKE 
          ZJP    LOSTC       JUMP IF CONTACT LOST 
          LDN    0
          UJN    WCRX 
* /---   BLOCK      WCPE-PUTCH 00 000   76/05/17  11.08 
          TITLE  ODD CHANNEL STATUS/PUT CHARACTER 
* 
* * WCPE
* 
*         THIS ROUTINE INPUTS THE ODD CHANNEL STATUS
*         AND CHECKS FOR CHARACTER PHASE ESTABLISHED. 
* 
*         OUTPUT PARAMETERS 
*         IF (A)  = ZERO CHARACTER PHASE NOT ESTABLISHED
*                 = POSITIVE - ESTABLISHED SYNCHRONIZATION
* 
 WCPE     SUBR
* 
* * *     INPUT STATUS
          CALL   ICHR2
* 
* * *     CHECK CARRIER BIT 
          LPC    MCST 
          NJN    WP1         JUMP IF CARRIER NOT ON 
* 
* * *     CHECK FOR STATUS BIT
          LDD    PS 
          LPC    MCPH 
          LMC    MCPH 
          UJN    WCPEX
* 
* * *     ERROR--CARRIER NOT ON.
 WP1      BSS    0
          CALL   HERROR,HCNO
          SPACE  1
* 
* * PUTCHR
* 
*         WAIT FOR CHARACTER REQUEST STATUS TO APPEAR THEN
*         OUTPUT THE INDICATED CHARATER.
* 
*         INPUT PARAMETER 
*         (A) = CHARACTER TO BE OUTPUT. 
* 
 PUTCHR   SUBR
* 
* * *     SAVE CHARACTER TO BE OUTPUT 
          STD    OC 
* 
* * *     WAIT FOR CHARACTER REQUEST STATUS 
          LDC    MCRQ 
          RJM    WCR
* 
* * *     OUTPUT CHARACTER
          LDM    PARTBLE,OC 
          RJM    OCHR 
          UJN    PUTCHRX
* /---   BLOCK      GETCHR     00 000   78/05/11  22.15 
          TITLE  GETCHR 
* 
* * GETCHR
* 
*         THIS ROUTINE IS CALLED AFTER INPUT HAS
*         BEEN RECEIVED TO CHECK AND CLASSIFY IT. 
* 
*         INPUT PARAMETERS
*         (CHAR) = INPUT BYTE.
*         OUTPUT PARAMETERS 
*         (A) = -1 SYNC CODE
*               0 DATA CHARATER RETURNED
*               1 CONTROL CODE RETURNED 
* 
 GETCHR   SUBR
* 
* * *     SAVE ONLY CHARACTER INFO IN BYTE. 
          LDD    CHAR 
          LPC    MCHR8       MASK OFF STATUS BITS 
          STD    TT          SAVE CHAR. PLUS PARITY BIT 
          LPC    MCHR7       MASK OFF PARITY BIT
          STD    CHAR        SAVE CHAR. MINUS PARITY BIT
* 
* * *     CHECK CHARACTER PARITY
          LDM    PARTBLE,CHAR   CHAR. PLUS CORRECT PARITY 
          SBD    TT          WAS INPUT THE SAME 
          NJP    GC2         JUMP IF NOT
* 
* * *     FOUND GOOD CHAR. - CLEAR BAD CHARACTER COUNT
          LDN    0
          STD    BADC 
* 
* * *     CHECK FOR SYNC CHARACTER
          LDD    CHAR 
          SBN    CSYN 
          NJN    GC1         JUMP IF NOT SYNC CODE. 
          LCN    1
          UJN    GETCHRX
* 
* * *     SET RETURN TO INDICATE DATA OR CONTROL CHAR.
 GC1      BSS    0
          LDD    CHAR 
          SHN    -6          ONLY INDICATOR BIT REMAINS 
          LMN    1           COMPLEMENT IT. 
          UJN    GETCHRX
* 
* * *     CHARACTER PARITY ERROR
 GC2      BSS    0
          AOM    PECNT       COUNT OF TOTAL BAD CHAR. 
          STD    NAKFLAG     INDICATE MESSAGE HAS AN ERROR
          AOD    BADC        CONSECUTIVE BAD CHAR. COUNT
          SBN    PEND        CHECK FOR TOO MANY BAD CHAR. 
          MJP    GETCHRX     IF NOT TOO MANY
* 
* * *     IF WAITING FOR LINKCTL COMMAND, SEND ERROR LATER
          LDM    WAITF
          NJP    WAITL       JUMP IF WAITING ON COMMAND 
* 
* * *     ERROR--TOO MANY BAD CHARACTERS
          CALL   HERROR,HBCH
* /---   BLOCK      PACK       00 000   76/05/17  11.08 
          TITLE  PACK DATA
* 
* * PACK
* 
*         THIS ROUTINE TAKES LAST CHARACTER INPUT AND 
*         PACKS IT INTO THE NEXT PPU WORD IN THE INPUT
*         BUFFER.  TWO CHARACTERS ARE PUT INTO EACH WORD
*         THUS IT HAS TO BE DETEMINED WHETHER THIS
*         CHARACTER IS TO BE PUT IN THE UPPER(BITS 6-11)
*         LOWER(BITS 0-5) POSITION IN THE CURRENT WORD. 
* 
 PACK     SUBR
* 
* * *     UPDATE MESSAGE PARITY CHECK 
* 
          LDD    CHAR        INPUT CHARACTER
          LMD    CKI         MESSAGE PARITY 
          STD    CKI
* 
* * *     CHECK WHERE IN BYTE THIS CHARACTER SHOULD GO
* 
          AOD    ULP
          LPN    1
          ZJN    PK1         JUMP IF LOWER CHARACTER
* 
* * *     ADVANCE PPU WORD POINTER TO NEXT WORD 
* 
          AOD    WP 
* 
* * *     CHECK FOR BUFFER OVERFLOW 
* 
          ADC    -MAXIN      MAX. NO. OF BYTES TO ASSEMBLE
          MJN    PK0         JUMP IF NO OVERFLOW
* 
* * *     ERROR--MESSAGE TOO LONG 
          CALL   HERROR,HMLT
* 
* * *     PUT NEW CHARACTER INTO UPPER CHARACTER POSITION 
*         IN THIS PPU WORD. 
* 
 PK0      BSS    0
          LDD    CHAR        INPUT CHARACTER
          SHN    6           POSITION CHARACTER 
          STM    OSTART-1,WP  STORE IN BUFFER 
          UJN    PACKX       GET NEXT WORD
* 
* * *     STORE NEW CHARACTER IN LOWER CHARACTER POSITION 
*         OF PPU WORD.
* 
 PK1      BSS    0
          LDD    CHAR        INPUT CHARACTER
          LPN    77B         GET RID OF DATA BIT
          RAM    OSTART-1,WP  STORE INTO DATA BUFFER
          UJN    PACKX       GET NEXT CHARACTER 
* /---   BLOCK      UNPACK     00 000   77/08/17  14.01 
          TITLE  UNPACK 
* 
* * UNPACK
* 
*         THIS ROUTINE EXTRACTS ONE CHARACTER AT A TIME 
*         FROM THE OUTPUT BUFFER(XBUFF) AND SAVES IT
*         IN -OC-.  'THE CHARACTERS ARE STORED TWO TO A 
*         PPU WORD SO IT MUST DETERMINE WHETHER THE NEXT
*         CHARACTER IS IN THE UPPER(BITS 6-11) OR LOWER 
*         (BITS 0-5) POSITION OF THE WORD.
* 
*         OUTPUT PARAMETER
*         (A) = NONZERO IF CHARACTER IN -OC-
*             = ZERO IF NO MORE CHARACTERS IN BUFFER. 
* 
 UNPACK   SUBR
* 
* * *     IS NEXT CHARACTER TO BE TAKEN FROM UPPER OR 
*         LOWER PORTION OF PPU WORD.
* 
          AOD    ULU
          LPN    1
          ZJN    UPK1        JUMP IF LOWER
* 
* * *     CHECK TO SEE IF ALL DATA HAS BEEN OUTPUT
* 
          LDD    WU          CURRENT  POSITION IN BUFFER
          SBD    NW          SUBTRACT LAST DATA POSITION
          ZJN    UNPACKX     IF ALL DONE
          AOD    WU          BUMP TO NEXT WORD
* 
* * *     ISOLATED NEXT CHARACTER FROM UPPER CHARACTER
*         POSITION OF PPU WORD. 
* 
          LDM    ISTART-1,WU
          SHN    12          POSITION CHARACTER IN LOWER
*                            6 BITS OF -A-
          UJN    UPK2        GO MASK CHARACTER
* 
* * *     NEXT CHARACTER IN LOWER 6 BITS OF PPU WORD
* 
 UPK1     BSS    0
          LDM    ISTART-1,WU
* 
* * *     ISOLATE CHARACTER, ADD DATA BIT, AND SAVE 
* 
 UPK2     BSS    0
          LPN    77B
          ADC    DCON        ADD DATA BIT 
          STD    OC          SAVE OUTPUT CHARACTER
          UJN    UNPACKX
* /---   BLOCK      DATAIN     00 000   76/06/16  15.24 
          TITLE  DATAIN 
* 
* 
* * DATAIN
* 
*         THIS ROUTINE INPUTS DATA CHARACTERS SENT BY 
*         THE REMOTE SITE AND PACKS THEM TWO CHARACTERS 
*         PER BYTE INTO THE DATA BUFFER.  THE DATA INPUT
*         IS TERMINATED BY AN -EOD-(END OF DATA), -EOB- 
*         (END OF BLOCK), OR -EOF-(END OF FILE) CONTROL 
*         CHARACTER, WHICH IS INTURN FOLLOWED BY THE
*         MESSAGE PARITY CODE.
* 
 DATAIN   SUBR
* 
* * *     INITIALIZE  POINTERS
          LDN    0
          STD    ULP
          STD    WP 
          STD    CKI
          STD    NAKFLAG
* 
* * *    CLEAR SYNC CODE COUNTER
 DI1      BSS    0
          LDN    0
          STD    SC 
* 
* * *     WAIT FOR FIRST CHARATER 
 DI2      BSS    0
          CALL   WCR,MCRD 
          ZJP    LOSTC       PROBABLY LOST CONTACT
* 
* * *     PROCESS INPUT CHARACTER 
          RJM    GETCHR 
          MJN    DI3         JUMP IF SYNC CODE
          NJN    DI4         JUMP IF CONTROL CODE 
* 
* * *     PUT DATA AWAY 
          CALL   PACK 
          UJN    DI1
* 
* * *     SYNC CODE INPUT, BUMP COUNTER, IF TOO MANY ARE
*         RECEIVED BEFOR NEXT DATA CHARACTER HAVE MESSAGE 
*         RESENT. 
 DI3      BSS    0
          AOD    SC          BUMP SYNC CODE COUNTER 
          ADC    -SYEND1     CHECK FOR TOO MANY SYNC CHAR.
          MJN    DI2         GET NEXT CHAR. IF NOT
          UJP    DI6         SET NAKFLAG AND EXIT 
* /---   BLOCK      DATAIN     00 000   84/11/15  11.34 
* 
* * *     CONTROL CODE RECEIVED, CHECK FOR -EOD-, -EOB-,
*         OR -EOF-. 
 DI4      BSS    0
          LDN    CEOD 
          SBD    CHAR 
          ZJN    DI5         JUMP IF -EOD-
* 
          LDN    CEOB 
          SBD    CHAR 
          ZJN    DI5         JUMP IF -EOB-
* 
          LDN    CEOF 
          SBD    CHAR 
          ZJN    DI5         JUMP IF -EOF-
* 
* * *     BAD CHARACTER SET NAKFLAG AND GET NEXT CHARACTER
          LDN    1
          STD    NAKFLAG
          AOM    BDCNT       BUMP ERROR COUNT 
          UJP    DI2
* 
* * *     PUT CONTROL CODE IN -LINKCTL- RESPONSE. 
 DI5      BSS    0
          LDD    CHAR 
          STM    OHDR+REOM
* 
* * *     GET NUMBER OF PPU WORDS INPUT 
          LDD    WP 
          STM    RWDS+OHDR
* 
* * *     CALCULATE NUMBER OF CM WORDS IN MESSAGE 
          ADN    4           EXTRA WORDS IN HEADER. 
          CALL   CMCAL
* 
* * *     INPUT MESSAGE PARITY CODE 
          CALL   WCR,MCRD    WAIT FOR INPUT 
          ZJP    LOSTC       JUMP IF LOST CONTACT 
* 
* * *     PROCESS INPUT 
          CALL   GETCHR 
          LDD    CHAR 
* 
* * *     COMPARE GENERATED PARITY TO ONE RECEIVED
          SBD    CKI
          ZJN    DI7
* 
* * *     SET NAKFLAG AND EXIT
 DI6      BSS    0
          LDN    1
          STD    NAKFLAG
          AOM    LPCNT       BUMP ERROR COUNT 
 DI7      LJM    DATAINX
* /---   BLOCK      DATAOUT    00 000   76/06/16  14.54 
          TITLE  DATAOUT
* 
* * DATAOUT 
* 
*         THIS ROUTINE TRANSMITS DATA TO THE REMOTE 
*         SITE.  THE DATA IS GIVEN TO THE DRIVER BY 
*         -LINKCTL-.  THE DATA IS THEN UNPACKED A 
*         CHARACTER AT A TIME AND TRANSMITTED.  -LINKCTL- 
*         ALSO SUPPLIES THE CONTROL CODE WHICH WILL 
*         FOLLOW THIS MESSAGE(EOD, EOB, OR EOF).  THIS
*         ROUTINE ALSO GENERATES A MESSAGE PARITY WHICH 
*         IS TRANSMITTED FOLLOWING THE END OF MESSAGE 
*         CONTROL CHARACTER.
* 
 DATAOUT  SUBR
* 
* * *     OUTPUT START OF MESSAGE CHARACTER 
          LDM    IHDR+RSOM
          CALL   PUTCHR 
* 
* * *     INITIALIZE POINTERS 
          LDN    0
          STD    ULU
          STD    WU 
          STD    CKO
* 
* * *     GET NUMBER OF PPU WORDS IN DATA FIELD 
          LDM    RWDS+IHDR
          ADN    1           INCLUDE MESSAGE NUMBER 
          STD    NW 
* 
* * *     GET NEXT CHARACTER
 DO1      BSS    0
          RJM    UNPACK 
          ZJN    DO6         JUMP IF ALL DONE 
* 
* * *     OUTPUT NEXT CHARACTER 
          CALL   PUTCHR 
* 
* * *     UPDATE MESSAGE PARITY 
          LDD    OC 
          LMD    CKO
          STD    CKO
          UJN    DO1         GET NEXT CHARACTER 
* 
* * *     ALL DATA OUTPUT, OUTPUT END OF MESSAGE CHARACTER
 DO6      BSS    0
          LDM    IHDR+REOM    GET CHARACTER FROM -LINKCTL-
          RJM    PUTCHR      SEND IT. 
* 
* * *     OUTPUT MESSAGE PARITY CODE. 
          LDD    CKO
          RJM    PUTCHR 
          UJN    DATAOUTX 
* /---   BLOCK      MESSOUT    00 000   78/05/11  22.13 
          TITLE  SEND MESSAGE 
* 
* * MESSOUT 
* 
*         SEND MESSAGE TO REMOTE SITE AND WAIT FOR
*         ACKNOWLEDGE(ACK OR NAK).  IF A -NAK- IS 
*         RECEIVED OR AN ERROR RESEND THE MESSAGE.
* 
 MESSOUT  SUBR
          LDN    0
          STD    RESEND      CLEAR RESEND COUNT 
* 
* * *     SEND MESSAGE
MO1       BSS    0
          CALL   DATAOUT
* 
* * *     SET SYNC CODE COUNTER TO ZERO 
          LDN    0
          STD    SC 
* 
* * *     WAIT FOR ACK OR NAK.
 MO2      BSS    0
          CALL   WCR,MCRD 
          ZJP    LOSTC       JUMP IF CONTACT LOST 
* 
* * *     PROCESS INPUT 
          CALL   GETCHR 
          ZJN    MO5         RESEND MESSAGE BAD CHR.
          PJN    MO4         JUMP IF CONTROL CHAR.
* 
* * *     INCREMENT SYNC CODE COUNTER 
          AOD    SC 
          ADC    -SYEND2
          MJP    MO2         WAIT FOR NEXT CHAR.
* 
* * *     TOO MANY SYNC CODES 
          AOM    SCCNT       BUMP ERROR COUNTS
          UJP    MO5
* 
* * *     CONTROL CHARACTER FOUND  IS IT A ACK. 
 MO4      BSS    0
          LDD    CHAR 
          SBN    CACK 
          ZJN    MESSOUTX 
          AOM    BCCNT       BUMP ERROR COUNT 
* 
* * *     ALLOW 5 RESENDS, THEN GIVE UP 
 MO5      BSS    0
          AOD    RESEND      BUMP COUNTER 
          SBN    RSCNT       TOO MANY RESENDS ALREADY 
          MJP    MO1         NO, RESEND THE MESSAGE 
          CALL   HERROR,HRSD ISSUE ERROR
* /---   BLOCK      MESSIN     00 000   84/11/15  11.35 
          TITLE  RECEIVE A MESSAGE
* 
* * MESSIN
* 
*         INPUT MESSAGE FROM REMOTE SITE, THEN SEND 
*         AN ACK OR NAK DEPENDING ON CONDITION OF MESSAGE 
*         RECEIVED. 
* 
*         OUTPUT PARAMETERS 
*         (A) = ZERO IF MESSAGE NUMBER OKAY 
*               NONZERO OTHERWISE.
* 
 MESSIN   SUBR
* 
* * *     WAIT FOR FIRST INPUT CHARACTER. 
 MI1      BSS    0
          CALL   WCR,MCRD 
          ZJP    LOSTC       JUMP IF CONTACT LOST 
          CALL   GETCHR 
          MJN    MI3         JUMP IF SYNC CHARACTER 
          ZJN    MI3         JUMP IF NOT CONTROL CHAR.
* 
* * *     SAVE START OF MESSAGE CHARACTER.
          LDD    CHAR        GET CHARACTER
          STM    OHDR+RSOM
* 
* * *     INPUT REST OF MESSAGE 
          CALL   DATAIN 
* 
* * *     WAS MESSAGE IN GOOD SHAPE 
          LDD    NAKFLAG
          ZJN    MI2         JUMP IF YES
* 
* * *     OTHERWISE HAVE MESSAGE RESENT.
          CALL   PUTCHR,CNAK
          UJP    MI1
* 
* * *     INDICATE TO REMOTE SITE THAT MESSAGE IS OKAY
 MI2      BSS    0
          CALL   PUTCHR,CACK  SEND POSITIVE ACKNOWLEDGE 
          UJN    MESSINX
* 
* * *     JUST RECEIVED SYNC CHAR.-ARE WE IN STARTUP
 MI3      BSS    0
          LDD    FUNC 
          SBN    FASU 
          NJP    MI1         JUMP IF NOT
* 
* * *     IF STARTUP ONLY WAIT CERTAIN NUMBER OF CHAR. TIMES
          AOD    SC          INCREMENT COUNTER
          ADC    -SYEND      MAX. NUMBER ALLOWED. 
          MJP    MI1         JUMP IF TIME NOT UP
* 
* * *     OTHERWISE SEND MESSAGE BACK TO LINKCTL
          CALL   SERROR,SRDR
* /---   BLOCK      SELDC      00 000   78/01/22  20.30 
          TITLE  SELECT 6681 DATA CONVERTER 
* 
* * SELDC 
* 
*         THIS ROUTINE TAKES THE FOLLOWING STEPS IN SETTING 
*         UP THE 6681 AND 3266 FOR USE. 
*         1.DEACTIVATE THE CHANNEL
*         2.SELECT CONVERTER
*         3.CHECK 3266 PORTS
*         4.SELECT RESYNC AND SEND FUNCTION TO 311. 
* 
*         OUTPUT PARAMETERS 
*         IF (A) IS NEGATIVE, ERROR OCCURED.
*                   POSITVE, EVERYTHING IS OKAY.
* 
 SELDC    SUBR
          RJM    CCR
          NJN    SELDC1      IF EQUIP/CHANNEL RESERVED
          CALL   SERROR,SENA
 
 SELDC1   BSS    0
* 
* * *     DEACTIVATE THE CHANNEL IF NECESSARY 
          IJM    SELDC2,C=CH JUMP IF CHANNEL INACTIVE 
          DCN    C=CH,40B    DE-ACTIVATE THE CHANNEL
          RJM    TIMOUT 
          NJN    SELDC2      JUMP IF CHANNEL DEACTIVATED. 
* 
* * *     ERROR--CHANNEL DID NOT DROP 
          CALL   LREL        RELEASE EQUIPMENT RESERVATIONS 
          CALL   HERROR,HDCN
* 
* * *     SELECT CONVERTER
 SELDC2   BSS    0
          FNC    DCSC,C=CH   FUNCTION SELECT CONVERTER
          RJM    TIMOUT      WAIT FOR CHANNEL TO DEACTIVATE.
          NJN    SELDC4      JUMP IF CHANNEL DEACTIVATED
* 
* * *     ERROR--SELECT CONVERTER FUNCTION NOT ACCEPTED 
          CALL   LREL        RELEASE EQUIPMENT RESERVATIONS 
          CALL   HERROR,HFSC
* 
* * *     SET UP 311 SO IT IS READY TO SEND AND RECEIVE.
 SELDC4   BSS    0
          PORT   ODD         CONNECT TO ODD CHANNEL 
          RJM    ST6681      CHECK FOR FUNCTION REJECT
          MJN    SELDC5      IF ERROR 
* 
* * *     CONNECT TO EVEN CHANNEL 
          PORT   EVEN        CONNECT OT EVEN CHANNEL. 
          RJM    ST6681      CHECK FOR 6681 REJECT
 SELDC5   LJM    SELDCX      IGNORE ERRORS
          EJECT 
* 
* * TIMOUT
* 
*         ROUTINE TO MAKE SURE CHANNEL DEACTIVATES
*         WITHIN PROPER TIME LIMIT. 
* 
 TIMOUT   SUBR
          LDC    TOUT        TIME OUT COUNTER 
 TMO1     BSS    0
          IJM    TIMOUTX,C=CH     IF ALL QUIET
          SBN    1
          NJN    TMO1        JUMP IF COUNTER NOT EXPIRED
          UJN    TIMOUTX
* /---   BLOCK      6681       00 000   78/01/22  20.30 
          SPACE  6
* 
* * ST6681
* 
*         CHECK 6681 STATUS FOR FUNCTION REJECT.
* 
*         OUTPUT PARAMETERS 
*         IF (A) IS NEGATIVE FUNCTION WAS REJECTED. 
*                   POSITIVE EVERTHING IS OKAY. 
* 
 ST6681   SUBR
          FNC    DCCS,C=CH   STATUS FUNCTION
          ACN    C=CH,40B    ACTIVATE THE CHANNEL 
          IAN    C=CH,40B    INPUT STATUS 
          DCN    C=CH,40B 
          STD    PS          SAVE STATUS
          LPN    7           MASK REJECT BITS 
          ZJN    ST6681X
* 
* * *     ERROR--6681 REJECT CONNECT FUNCTION 
* 
          CALL   LREL        RELEASE EQUIPMENT RESERVATIONS 
          CALL   HERROR,HREJ
* /---   BLOCK      SEST       00 000   77/08/17  15.01 
          TITLE  SYNCHRONIZATION ESTABLISH
* 
* * *     SEST
* 
*         ESTABLISH SYNCHRONIZATION WITH REMOTE SITE. 
*         ON ENTRY (A) = NUMBER OF TIMES TO TRY 
* 
 SEST     SUBR
* 
* * *     SET LOOP COUNTER
          STD    TT 
* 
* * *     CLEAR SYNC CODE INDICATOR 
          LDN    0
          STM    SFLAG
* 
* * *     SELECT RESYNCH. FUNCTION
 SE0      BSS    0
          CALL   OCHR2,BRSY+BSND
* 
* * *     SET NUMBER SYNCH CODES TO SEND
          LDN    4
          STD    SC 
* 
* * *     WAIT FOR CHARACTER REQUEST STATUS 
 SE1      BSS    0
          RJM    PAUSE
          CALL   WCR,MCRQ    WAIT FOR CHAR. REQUEST 
          ZJN    SE3         JUMP IF NEVER FOUND CHAR. REQ. 
* 
* * *     OUTPUT SYNC CODE
          CALL   OCHR,CSYN   OUTPUT SYNC CODE.
* 
* * *     CHECK FOR SYNCHRONIZATION ESTABLISHED 
          CALL   WCPE 
          STM    SFLAG       SET SYNC. ACHIEVED FLAG
          NJN    SESTX       IF ESTABLISHED 
* 
* * *     HAVE ALL SYNCH CODES BEEN OUTPUT
          SOD    SC 
          NJP    SE1         JUMP IF NOT
* 
* * *     DECREMENT COUNTER AND QUIT IF ZERO
          SOD    TT 
          NJN    SE0
* 
* * *     ERROR - SYNCHRONIZATION NEVER ESTABLISHED 
          CALL   HERROR,HECP
* 
* * *     ERROR--INITIAL CHARACTER REQUEST DID NOT APPEAR 
 SE3      BSS    0
          LDD    CHAR        SAVE STATUS FOR RESPONSE 
          STD    PS 
          CALL   HERROR,HCRQ
* /---   BLOCK      CMCAL      00 000   77/08/29  15.27 
          TITLE  DIVIDE BY 5
* 
* * CMCAL 
* 
*         DIVIDE NUMBER IN -A- BY FIVE AND PUT RESULT IN
*         -DL-.  THE METHOD USED IS TO MULTIPLY THE 
*         NUMBER BY 205, THEN DIVIDE BY 1024.  THIS WORKS 
*         FOR NUMBERS UPTO 1200.
* 
 CMCAL    SUBR
* 
* * *     MULTIPLY BY 205. (N=NUMBER, *=MULTIPLY) 
* 
          STD    T1          SAVE N 
          SHN    1           N*2
          ADD    T1          (N*2)+N = (N*3)
          STD    T2          SAVE (N*3) 
          SHN    4           (N*3)*16 
          ADD    T2          (N*3)*16 + (N*3) = (N*51)
          SHN    2           (N*51)*4 = (N*204) 
          ADD    T1          (N*204)+N = (N*205)
* 
* * *     DIVIDE BY 1024
* 
          SHN    -10         (N*205)/1024 
          STD    DL          THE RESULT 
          UJN    CMCALX 
          TITLE  INCREMENT 5 BYTE COUNTER 
* 
* * AFIVE 
* 
*         INCREMENT BY ONE A 5 BYTE COUNTER DESIGNATED
*         BY THE ADDRESS IN A.  ALSO MOVE THE COUNTER 
*         TO LKBUF SO THAT IT CAN BE WRITTEN TO ECS.
* 
*         INPUT PARAMETERS';
*         (A) = ADDRESS OF BYTE ZERO OF COUNTER 
* 
* 
 AFIVE    SUBR
          STD    TT          SAVE ADDRESS 
          LDN    4
          STD    T1          INITIALIZE THE LOOP COUNTER
* 
* * *     INCREMENT COUNTER STARTING WITH BYTE 4
 AF1      BSS    0
          AOM    4,TT        INCREMENT THIS BYTE BY ONE 
          STM    LKBUF,T1    SAVE NEW VALUE FOR ECS TRANSFER
          SHN    -12         CHECK FOR OVERFLOW 
          ZJP    AF2         JUMP IF NO OVERFLOW
          SOD    TT          SET TO NEXT BYTE 
          SOD    T1          DECREMENT BYTE COUNTER 
          UJN    AF1
* 
* * *     MOVE REST OF COUNTER TO LKBUF 
 AF2      BSS    0
          SOD    TT 
          SOD    T1 
          MJN    AFIVEX      IF ALL DONE
          LDM    4,TT 
          STM    LKBUF,T1 
          UJN    AF2
* /---   BLOCK      PARGEN     00 000   77/02/15  14.05 
          TITLE  PARITY GENERATION
* 
* * PARGEN
* 
*         'THIS ROUTINE GENERATES A TABLE CONTAINING
*         ALL POSSIBLE 7 BIT COMBINATIONS THAT CAN
*         BE SENT AS DATA OR CONTROL CHARACTERS OVER
*         THE LINK PLUS THE APPROPRIATE PARITY BIT(ODD).
*         'THUS WHEN SENDING A CHARACTER, THE CHARACTER 
*         CAN BE USED AS AN INDEX INTO THIS TABLE TO GET
*         THE CHARACTER PLUS PARITY TO TRANSMIT.
* 
 PARGEN   SUBR
          LDC    127         128 POSSIBLE 7 BIT CHARATERS.
          STD    T1 
* 
* * *     MAIN LOOP DONE ONCE FOR EACH 7 BIT CHARATER.
* 
 PG1      BSS    0
          LDN    0           INITIALIZE BIT COUNTER 
          STD    T2 
          LDD    T1          SAVE WORKING COPY OF CURRENT 
          STD    T3            CHARACTER. 
          LDN    6           SEVEN BITS/CHARACTER 
          STD    T4 
* 
* * *     INTER LOOP - COUNTS NUMBER OF BITS IN CHARACTER 
* 
 PG2      BSS    0
          LDD    T3          GET SHIFTED 7 BIT CHARACTER
          SHN    1           POSITION NEXT BIT
          STD    T3          SAVE FOR NEXT LOOP 
          SHN    10          MOVE BIT TO TOP
          PJN    PG3         JUMP IF BIT NOT SET
          AOD    T2          BIT SET INCREMENT BIT COUNTER
 PG3      BSS    0
          SOD    T4          DECREMENT NUMBER OF BITS TESTED
          PJN    PG2         JUMP IF MORE BITS
* 
* * *     GENERATE CHARACTER WITH PARITY BIT
* 
          LDD    T2          LOAD BIT COUNT 
          LPN    1           ISOLATE PARITY BIT 
          LMN    1           TOGGLE BIT 
          SHN    7           POSITION PARITY BIT
          ADD    T1          ADD IN 7 BIT CHARACTER 
          STM    PARTBLE,T1  STORE IN TABLE 
* 
* * *     END OF MAIN LOOP - JUMP IF MORE TO DO.
* 
          SOD    T1          DECREMENT CHARACTER COUNTER. 
          PJP    PG1         JUMP IF NOT DONE 
          UJN    PARGENX
* /---   BLOCK      PAUSE      00 000   84/11/15  11.35 
          TITLE  PAUSE--CHECK FOR STORAGE MOVE OR ERROR CONDITIONS
*         PAUSE 
* 
*            THIS ROUTINE CHECKS TO SEE IF THE STORAGE
*         MOVE OR ERROR FLAGS AT THE CONTROL POINT ARE
*         SET.  IF NECESSARY, IT PAUSES AND THEN RESETS 
*         THE REFERENCE ADDRESSES.  IF THE CONTROL POINT
*         ERROR FLAG IS SET OR THERE IS NO CPU ACTIVITY 
*         AT THE CONTROL POINT, THE PPU IS DROPPED. 
* 
 PAUSE    SUBR
* 
* * *     RESET PAUSE COUNTER 
          LDC    TOUT2
          STD    TI 
* 
* * *     READ CONTROL POINT STATUS 
          LDD    CP 
          ADN    STSW 
          CRD    CM 
          LDD    CM+C.CPEF   ERROR FLAG 
          NJP    DPP2        EXIT IF CONTROL POINT ERROR. 
          LDD    CM+C.CPSTAT
          SHN    -11B 
          ZJP    DPP2        IF NO CPU ACTIVITY 
* 
* * *     CHECK FOR PAUSE CONDITION 
          LDN    CMCL 
          CRD    CM 
          LDD    CM 
          SBD    CP 
          NJN    PAUSEX      IF NO PAUSE REQUIRED 
          PAUSE  ST 
* 
* * *     READ CONTROL POINT STATUS WORD
          LDD    CP 
          ADN    STSW 
          CRD    CM 
          LDD    CM+C.CPEF
          NJP    DPP2        EXIT IF CONTROL POINT ERROR
* 
* * *     NEW PPU STATUS WORD ADDRESS 
          LDM    PU 
          SHN    6
          ADD    RA 
          SHN    6
          ADM    PL 
          PLANT  CM,PPST
* 
* * *     NEW COMMUNICATION BUFFER ADDRESS. 
          LOADCM PPST 
          ADN    2
          PLANT  CM,COMBF 
* 
* * *     ECS TRANSFER BUFFER ADDRESS 
          LOADCM PPST 
          ADN    22 
          PLANT  CM,TRNBF 
          LJM    PAUSEX 
          SPACE  2
* 
* *       FRMCHK
* 
*         CHECK FOR FRAMAT RE-INITIALIZING.  'THIS HAPPENS
*         WHEN FRAMAT IS DROPPED AND RELOADED FOLLOWING 
*         AN ECS ERROR. 
* 
 FRMCHK   SUBR
* 
* * *     RESET TIME OUT COUNTER
          LDN    50 
          STD    FRCHK
* 
* * *     READ FRAMAT STATUS WORD 
 FRMCHK1  BSS    0
          LDN    0
          STD    ECSOFF 
          LDN    1
          STD    ECS
          CALL   READECS,FORINIP
* 
* * *     CHECK TO SEE IF FRAMAT RE-INITIALIZING
          LDM    LKBUF
          SHN    6
          PJN    FRMCHKX
* 
* * *     WAIT UNTIL FRAMAT DONE INITIALIZING 
          CALL   PAUSE
          DELAY  5000 
          UJP    FRMCHK1
* /---   BLOCK      ERROR      00 000   84/11/15  11.35 
          TITLE  SOFTWARE AND HARDWARE ERROR ROUTINES 
* 
* *       SERROR
* 
*         THIS ROUTINE PROCESSES SOFTWARE ERRORS AS FOLLOWS'; 
*         1. PUT ERROR CODE INTO RESPONSE BUFFER. 
*         2. WRITE RESPONSE TO CM 
* 
* *       INPUT PARAMETERS
*         -A- MUST CONTAIN THE APPROPRIATE ERROR CODE.
* 
 SERROR   SUBR
          STM    OBF+RERR 
          RJM    WRITE
          UJP    MAIN        GO BACK TO MAIN LOOP 
          SPACE  4
* 
* *       HERROR
* 
*         THIS ROUTINE PROCESSES HARDWARE ERRORS AS FOLLOWS'; 
*         1.PUT ERROR CODE INTO RESPONSE BUFFER.
*         2.PUT HARDWARE STATUS INTO RESPONSE BUFFER. 
*         3.WRITE RESPONSE BACK TO CM.
* 
* *INPUT PARAMETERS 
*         -A- MUST CONTAIN ERROR CODE.
*         -PS- MUST CONTAIN APPROPRIATE STATUS
* 
 HERROR   SUBR
          STM    OBF+RERR    PUT ERROR CODE IN RESPONSE 
          LDD    PS          GET HARDWARE STATUS
          STM    OBF+RSTA    PUT STATUS INTO RESPONSE 
          RJM    WRITE       WRITE RESPONSE TO CM.
          LDD    MODE        CHECK FOR TERMINAL MODE
          ZJP    MAIN        JUMP IF DATA MODE
          LDC    LABK        KEY TO BE PRESSED
          STM    RQKEY
          CALL   PREQ,PKEY   SEND A KEY TO WAKE UP LINKCTL
          LJM    MAIN 
          SPACE  2
* 
* *LOSTC
*         LOST CONTACT WITH REMOTE SITE EXIT
* 
 LOSTC    BSS    0
          CALL   HERROR,HLCR
* /---   BLOCK      DPP        00 000   78/05/11  22.05 
          TITLE  EXIT ROUTINES
 DPP      BSS    0
          CALL   TMEND
          CALL   PREQ,PKILL  SEND KILL REQUEST TO PLATO.
 DPP2     BSS    0
          LDN    1           MARK DROPPING PPU
          STM    DPPF 
          CALL   STDPP       IF EQUIPMENT UP SEND STOP CODE.
          CALL   LREL        RELEASE COMMUNICATION LINK 
          MONITOR DPPM
          LJM    PPR         EXIT TO IDLE LOOP. 
          SPACE  2
* 
* *DROPCHK
* 
*         CHECK FOR PLATO LESSON DROP SIGNAL
* 
 DROPCHK  SUBR
          LOADCM PPST        PPU STATUS WORD. 
          CRD    CM 
          LDD    CM+4 
          ZJP    DPP         JUMP IF BIT CLEARED
          UJN    DROPCHKX 
          TITLE  SEND END LINK
* 
* *       STDPP 
* 
*         'THIS ROUTINE SELECTS -STOP SEND- ON 3266.
* 
 STDPP    SUBR
* 
* * *     EXIT IF EQUIPMENT OR CHANNEL IS NOT RESERVED. 
* 
          RJM    CCR
          ZJN    STDPPX 
* 
* * *     SEND 100 BAD CHARACTERS TO OTHER SYSTEM 
          LDC    100
          STD    RESEND      SET CHARACTER COUNT
* 
* * *     WAIT FOR CHARACTER REQUEST
 STD1     BSS    0
          LDC    7777B
          STD    D0          NO. OF TIMES TO LOOK FOR STATUS
* 
* * *     CHECK FOR CHARACTER REQUEST STATUS
 STD2     BSS    0
          CALL   ICHR        INPUT STATUS 
          LPC    MCRQ        CHAR. REQUEST MASK 
          NJP    STD3        JUMP IF STATUS APPEARED
* 
* * *     DECREMENT STATUS CHECK COUNTER
          SOD    D0 
          ZJP    STD4        JUMP IF NO CHAR. REQUEST 
          UJP    STD2        LOOP AND CHECK AGAIN 
* 
* * *     SEND CHARACTER
 STD3     BSS    0
          LDN    3
          CALL   OCHR        OUTPUT CHAR. 
* 
* * *     HAVE 100 CHAR. BEEN OUTPUT
          SOD    RESEND      DECREMENT COUNTER
          PJP    STD1        LOOP IF NOT
* 
* * *     SET UP CONTROLLER FOR NEXT TRY
 STD4     BSS    0
          CALL   OCHR2,BSTP+BRSY
          LJM    STDPPX 
* /---   BLOCK      T DPP      00 000   77/09/06  00.40 
          TITLE  TERMINAL MODE TERMINATION
* 
* * TMEND 
* 
*         THIS ROUTINE DOES THE EXTRA PROCESSING NEEDED 
*         WHEN LEAVING TERMINAL MODE PROCESSING ROUTINES. 
* 
 TMEND    SUBR
          LDD    MODE 
          ZJN    TMENDX      IF NOT IN TERMINAL MODE
* 
* * *     PRESS KEY ON CALLING STATION
* 
          LDC    LABK        PRESS A LAB KEY
          STM    RQKEY
          CALL   PREQ,PKEY
* 
* * *     CLEAR FRAMER STATUS WORD
          CALL   LCLEAR,5    CLEAR 5 BYTES OF LKBUF 
          LDN    1
          STD    ECS         WRITE ONE WORD OF ECS
          LDM    FRAMID      OFFSET TO CORRECT WORD 
          STD    ECSOFF 
          CALL   WRITECS,PIOSTS 
          UJN    TMENDX 
 
 
* 
* * LCLEAR
* 
*         CLEAR INDICATED NUMBER OF BYTS IN -LKBUF- 
* 
*         INPUT PARAMETER 
*         (A) = NUMBER OF BYTES TO CLEAR
* 
 LCLEAR   SUBR
          SBN    1
          STD    T1 
 LCL      BSS    0
          LDN    0
          STM    LKBUF,T1 
          SOD    T1 
          PJN    LCL         JUMP IF MORE TO CLEAR
          UJN    LCLEARX
* /---   BLOCK      PREQ       00 000   78/05/11  21.52 
          TITLE  SEND PLATO REQUEST 
* 
* * PREQ
* 
*         SEND REQUEST TO PLATO 
*         (A) CONTAINS REQUEST CODE ON ENTRY. 
*         (RQKEY) CONTAINS KEY VALUE FOR REQUEST. 
* 
 PREQ     SUBR
          STD    TT          SAVE REQUEST CODE
* 
* * *     CHECK FOR PENDING REQUEST 
 PREQ1    BSS    0
          LOADCM PPST        ADDRESS OF CM BUFFER 
          ADN    1           BUMP TO REQUEST SLOT 
          CRD    T1          MAKE SURE NO REQUEST PENDING 
          LDD    T1 
          NJN    PREQ2       JUMP IF PENDING REQUEST
* 
* * *     SET UP NEW REQUEST
          LDD    TT          GET REQUEST CODE 
          STD    CM+4        PUT REQUEST CODE INTO BUFFER 
          LDM    RQKEY       GET KEY TO PUT INTO REQUEST
          STD    CM+3 
          LDD    STATION     PUT STATION NUMBER IN REQUEST
          STD    CM+2 
          LDN    0
          STD    CM+1 
          LDC    4000B       SET REQUEST BIT
          STD    CM 
* 
* * *     GIVE NEW REQUEST TO PLATO 
          LOADCM PPST        NOTHING PENDING WRITE NEW REQ. 
          ADN    1
          CWD    CM 
          UJN    PREQX
* 
* * *     WAIT FOR PENDING REQUEST TO BE PROCESSED
 PREQ2    BSS    0
          DELAY  4000 
          CALL   PAUSE
          UJP    PREQ1
* 
* /---   BLOCK      LOOPCHK    00 000   84/11/15  11.35 
          TITLE  PROCESS 3266 INPUT 
* 
* * LOOPCHK 
* 
*         PROCESS 3266 INPUT WHILE WAITING ON LINKCTL 
*         TO SEND NEXT COMMAND. 
* 
 LOOPCHK  SUBR
* 
* * *     EXIT IF EQUIPMENT/CHANNEL NOT RESERVED
          RJM    CCR
          ZJN    LOOPCHKX 
* 
* * *     SET SPECIAL WAIT-ON-LINKCTL FLAG
          LDN    1
          STM    WAITF
* 
* * *     WAIT FOR INPUT CHARACTER
          CALL   WCR,MCRD 
          ZJP    WAITL       JUMP IF NO CHARACTER APPEARED
* 
* * *     PROCESS NEW CHARACTER 
          CALL   GETCHR 
* 
* * *     CLEAR SPECIAL FLAG
          LDN    0
          STM    WAITF
          UJN    LOOPCHKX 
 
          TITLE  WAIT ON LINKCTL
* 
* * WAITL 
* 
*         THIS ROUTINE IS CALLED IF THE LINK IS DROPPED 
*         WHILE CLD IS WAITING FOR A LINKCTL COMMAND. 
*         WHEN THE NEXT COMMAND ARRIVES LINKCTL IS
*         INFORMED OF THE ERROR.
* 
 WAITL    BSS    0
* 
* * *     CHECK FOR PAUSE CONDITION 
          CALL   PAUSE
* 
* * *     CHECK FOR DROP SIGNAL FROM LINKCTL
          CALL   DROPCHK
* 
* * *     CHECK FOR LINKCTL COMMAND 
          CALL   READSW 
          ZJN    WAITL       NO NEW COMMAND, LOOP 
* 
* * *     NEW COMMAND ARRIVED, SEND ERROR TO LINKCTL
          CALL   HERROR,HBCH
* /---   BLOCK      EQUATES    00 000   78/05/11  22.16 
          TITLE  EQUATES
************************************************************************
* 
 LAB1K    EQU    213B        LAB1 KEY CODE
* 
 LABK     EQU    212B        LAB KEY CODE 
* 
 LKMASK   EQU    177B        LINKIO BUFFER LENGHT MASK
* 
 TMASK    EQU    777B        TERMINAL MODE MODULO MASK
* 
 CHPK     EQU    2           CHARACTERS PER KEY 
* 
 CHPF     EQU    4           CHARACTERS PER FRAME 
* 
 ALSEVEN  EQU    7777B       CONSTANT 
* 
 TOUT     EQU    777B        TIME OUT LOOP COUNTER
* 
TOUT2     EQU    100B 
* 
 MCHR8    EQU    377B        8 BIT CHARACTER MASK 
* 
 MCHR7    EQU    177B        CHARACTER MASK FOR DATA INPUT
* 
 DCON     EQU    100B        BIT ADD TO INDICATE DATA 
*                            CHARACTER. 
 RSCNT    EQU    30          NUMBER OF TIMES TO RESEND
*                            A MESSAGE BEFORE GIVING UP.
 PEND     EQU    30          NUMBER OF CONSECUTIVE BAD
*                            CHAR. BEFORE GIVING UP.
 SYEND    EQU    2000        NUMBER OF SYNC. CHAR TO WAIT 
*                            WHEN CHECKING FOR REMOTE REQ.
 SYEND1   EQU    10          NUMBER CONSECUTIVE SYNC CHAR 
*                            ALLOWED DURING A MESSAGE.
 SYEND2   EQU    500         NUMBER OF SYNC. CHAR. TO WAIT
*                            WHEN LOOKING FOR ACK/NAK.
 MAXCM    EQU    60          MAXIMUM SIZE OF LINKCTL REQUEST
* 
 XFORINIP EQU    2           ECS ADDRESS OF FORMATTER-
*                            FRAMER STATUS WORD 
************************************************************************
* /---   BLOCK      DEFINES    00 000   78/05/11  21.58 
          TITLE  STORAGE DEFINITIONS
************************************************************************
* 
* 
 CLEQ     DATA   7777B       EST ORDINAL OF -CL- AFTER
*                            EQUIPMENT RESERVED OTHERWISE 
*                            SET TO ALL SEVENS. 
 CLCH     DATA   7777B       SET TO ALL SEVENS UNTIL
*                            COMMUNICATION CHANNEL IS 
*                            RESERVED, THEN SET TO CHANNEL. 
 SFLAG    BSSZ   1           0 IF SYNC. NOT ACHIEVED, 
*                            NONZERO OTHERWISE
 WAITF    BSSZ   1           1 = PROCESSING INPUT WHILE 
*                            WAITING FOR LINKCTL COMMAND. 
*                            0 ALL OTHER TIMES. 
 RQKEY    BSSZ   1           KEY IN PRESS REQUEST TO PLATO
* 
 PECNT    BSSZ   1           NUMBER OF CHARACTER PARITY 
*                            ERRORS.
 BDCNT    BSSZ   1           NUMBER OF BAD CHARACTERS.
* 
 LPCNT    BSSZ   1           NUMBER OF BAD LONGITUDINAL 
*                            PARITY CHARACTERS. 
 SCCNT    BSSZ   1           NO. OF MESSAGES RESENT BECAUSE 
*                            NO RESPONSE WAS RECEIVED.
 BCCNT    BSSZ   1           NO. OF MESSAGES RESENT BECAUSE 
*                            RESPONSE WAS NOT AN -ACK-. 
 LKBUF    BSSZ   40          ECS READ/WRITE BUFFER
* 
 IFRAMEX  BSSZ   1           TEMPORARY SAVE AREA FOR FRAME
*                            INDEX. 
 IFRAME   BSSZ   5           CLD FRAME POINTER MATCHES
*                            ECS RESIDENT LFRPNT. 
 PFRAME   BSSZ   5           CLD LINKIO POINTER MATCHES 
*                            ECS RESIDENT LKIN
 FRBUFF   BSSZ   2           TERMINAL MODE FRAME BUFFER.
* 
 KYBUFF   DATA   7777B       TERMINAL MODE KEY BUFFER.
* 
 LFRLTH   BSSZ   1           NO. OF TERMINAL WORDS IN 
*                            EACH FRAME.
 FRAMID   BSSZ   1           LINK FRAME ID
* 
 DPPF     BSSZ   1           NON-ZERO IF DROP PPU IN PROCESS
* 
 CLKU     BSSZ   2           RUNNING CLOCK
 CLKL     EQU    CLKU+1 
* 
 PU       BSSZ   2           CM ADDRESS OF PARAMETER AREA 
 PL       EQU    PU+1 
* 
* /---   BLOCK      DEFINES    00 000   78/01/04  21.30 
 ECU      BSSZ   2           ECS RA 
 ECL      EQU    ECU+1
* 
 ECSAD    BSS    0           ECS ADDRESS TABLE
 PKEYECS  BSSZ   2           KEY BUFFER 
* 
 PECSIN   BSSZ   2           KEYS-IN BIT TABLE
* 
 LINKIO   BSSZ   2           TERMINAL WORD BUFFER FOR 
*                            PASSING INFO TO THE FRAMER.
 LKIN     BSSZ   2           POINTER TO NEXT LOCATION IN
*                            TERMINAL WORD BUFFER.
 LFRBUF   BSSZ   2           FRAME BUFFERS
* 
 LFRPNT   BSSZ   2           POINTER TO NEXT LOCATION IN
*                            FRAME BUFFERS. 
 LFRLTHS  BSSZ   2           NO. OF TERMINAL WORDS IN EACH
*                            FRAME. 
 PIOSTS   BSSZ   2           FRAMER STATUS WORD - INDICATES 
*                            CLD IS READING FRAMES
 ECSLTH   EQU    *-ECSAD     LENGTH OF ECS ADDRESS TABLE
* 
 FORINIP  BSSZ   2           FORMATTER-FRAMER STATUS WORD 
*                            ECS ADDRESS
* /---   BLOCK      IBF        00 000   77/10/03  14.21 
          TITLE  COMMUNICATION BUFFERS
************************************************************************
* 
*         THIS BUFFER IS USED TO HOLD REQUESTS AND DATA 
*         FROM LINKCTL.  'THE SWITCH WORD IS CONTIGUOUS 
*         WITH THE REST OF THE BUFFER IN THE CM BUFFER
*         BUT IS READ SEPARATLY BY THE LINK DRIVER. 
* 
*         BYTE DESCRIPTIONS'; 
*      SWITCH WORD
*         / 0 / 0 / 0 / 0 / NUMBER OF WORDS IN REQUEST(CM) /
*      PARAMETER SECTION  (IBF) 
*         / 0 / 0 / 0 / 0 / LINK FUNCTION CODE (RFUNC) /
*         / RSTA1 / RSTA / UNUSED / UNUSED / RERR / 
*      MESSAGE INFO (IHDR)
*         / REOM / RWDS / STNO / RSOM / RMNO (ISTART) / 
*      START OF ACTUAL DATA (XBUFF) 
*         / 200 BYTES OF DATA / 
* 
 PLTH     EQU    2           CM WORDS IN PARAMETER SECTION
* 
 DLTH     EQU    300         PPU WORDS IN DATA BUFFERS
* 
 PPOS     EQU    1           OFFSET TO PARAMETER SECTION
*                            (CM WORDS) 
 DPOS     EQU    3           OFFSET TO MESSAGE INFO SECTION 
*                            (CM WORDS) 
 IBF      BSS    PLTH*5      PARAMETER SECTION
* 
 IHDR     BSS    5           MESSAGE INFO 
* 
 ISTART   EQU    IHDR+4      FIRST BYTE TRANSMITTED 
*                            (MESSAGE NUMBER) 
 XBUFF    BSS    DLTH        START OF ACTUAL DATA 
* 
* /---   BLOCK      IBF        00 000   77/09/07  23.18 
* 
* * *     FOLLOWING ARE LOCATIONS OF VARIOUS PARAMETERS 
*         SUPPLIED FOR CERTIAN LINK DRIVER FUNCTIONS. 
* 
 XPORTCH  EQU    XBUFF+4     WORD WHERE 311 CHANNEL IS
*                            RECEIVED FROM LINKCTL. 
 XECU     EQU    XBUFF+8     PLATO*S ECS RA UPPER 9 BITS
* 
 XECL     EQU    XBUFF+9     PLATO*S ECS RA LOWER 12 BITS 
* 
 XTMSTAT  EQU    XBUFF+9     TERMINAL MODE STATION NO.
* 
 XPKEYEC  EQU    XBUFF+13    ECS ADDRESS OF KEY BUFFER
* 
 XPECSIN  EQU    XBUFF+18    ECS ADDR. OF KEYS-IN BIT TABLE 
* 
 XLINKIO  EQU    XBUFF+23    ECS ADDR. OF TERMINAL WORD BUF.
* 
 XLKIN    EQU    XBUFF+28    ECS ADDRESS OF POINTER TO NEXT 
*                            POSITION IN TERMINAL WORD BUF. 
 XLFRBUF  EQU    XBUFF+33    ECS ADDRESS OF FRAME BUFFERS 
* 
 XLFRPNT  EQU    XBUFF+38    ECS ADDRESS OF FRAME BUFFER
*                            POINTER. 
 XFRLTHS  EQU    XBUFF+43    ECS ADDRESS OF FRAME LENGTH
*                            TABLE
 XPIOSTS  EQU    XBUFF+48    FRAMER STATUS WORD 
* 
 XLFRLTH  EQU    XBUFF+54    NO. OF TERMINAL WORDS PER
*                            FRAME. 
 XFRAMID  EQU    XBUFF+59    LINK FRAME ID
* 
 XPATTRN  EQU    XBUFF+9     TEST PATTERN FOR LOOP BACK 
* 
 XLOOPS   EQU    XBUFF+14    0=RECEIVE 100 LOOPBACK CHARS 
*                            1=RECEIVE INFINITE NO. OF CHARS
* 
* * *     BYTE POSITIONS OF FIELDS IN PARAMETER SECTION 
* 
 RFUNC    EQU    4           FUNCTION CODE
* 
 RERR     EQU    9           ERROR CODE 
* 
 RSTA1    EQU    5           SECONDARY STATUS 
* 
 RSTA     EQU    6           EQUIPMENT STATUS 
* 
* 
* * *     BYTE POSITION OF FIELDS IN MESSAGE INFO SECTION 
* 
 RSOM     EQU    3           START OF MESSAGE CHARACTER 
* 
 REOM     EQU    0           END OF MESSAGE CHAR. 
* 
 STNO     EQU    2           LINKCTL STATION NO.
* 
 RMNO     EQU    4           MESSAGE NUMBER 
* 
 RWDS     EQU    1           PPU WORD COUNT 
* 
************************************************************************
* /---   BLOCK      OBF        00 000   77/09/07  01.20 
          TITLE  COMMUNICATION BUFFERS
************************************************************************
* 
*         THIS BUFFER IS USED FOR SENDING DATA AND
*         RESPONSE PARAMETERS TO LINKCTL.  'THE SWITCH
*         WORD IS APPENDED TO THE FOLLOWING BUFFER AFTER
*         IT IS WRITTEN TO CENTRAL MEMORY.
* 
*         BYTE DESCRIPTIONS'; 
*      SWITCH WORD  (BUILT AT A SEPARATE LOCATION)
*         / 4000B / 0 / 0 / NO. OF WORDS RETURNED(CM) / 0 / 
*      PARAMETER SECTION  (OBF) 
*         / 0 / 0 / 0 / 0 / UNUSED /
*         / RSTA1 / RSTA / UNUSED / UNUSED / RERR / 
*      MESSAGE INFO SECTION (IHDR)
*         / REOM / RWDS / STNO / RSOM / RMNO (OSTART) / 
*      START OF ACTUAL DATA (DBUFF) 
*         / 200 BYTES OF DATA / 
* 
 MAXIN    EQU    DLTH+4      MAXIMUM NUMBER OF BYTES+2 IN 
*                            A MESSAGE FROM REMOTE SITE.
 OBF      BSSZ   PLTH*5      OUTPUT BUFFER FOR PARAMETER
* 
 OHDR     BSS    5           MESSAGE INFO 
* 
 OSTART   EQU    OHDR+4      LOCATION TO STORE 1ST BYTE OF
*                            MESSAGE (MESSAGE NUMBER).
 DBUFF    BSS    DLTH        LOCATION OF FIRST BYTE OF DATA.
* 
* 
* * *     LOCATIONS OF VARIOUS PARAMETERS RETURNED TO 
*         LINKCTL.
* 
 DSTATS    EQU    DBUFF+4     LINK DRIVER STATISTICS
* 
************************************************************************
* /---   BLOCK      ERROR CODE 00 000   78/01/05  09.04 
          TITLE  ERROR CODES
************************************************************************
* 
* *       ERROR CODES 
*         CODES 0,1, AND 2 SAVE FOR PPU CALL ERRORS WHICH 
*         ARE GENERATED BY TUTOR COMMAND LOADPPU. 
* 
 SIFC     EQU    3           ILLEGAL FUNCTION CODE
 SENA     EQU    4           EQUIPMENT NOT AVAILABLE
 SCNA     EQU    5           CHANNEL NOT AVAILABLE
 SRDR     EQU    6           REMOTE DID NOT RESPOND AFTER 
*                            SENDING DURING STARTUP.
 HDCN     EQU    7           CHANNEL WOULD NOT DEACTIVATE.
 HFSC     EQU    8           COULD NOT SELECT 6681. 
 HECP     EQU    9           COULD NOT ESTABLISH CHARACTER
*                            PHASE IN 311.
 HCNO     EQU    10          CARRIER NOT ON IN 311. 
 HDSF     EQU    11          DATA SET FAILURE.
 HCRQ     EQU    12          INITIAL CHARACTER REQUEST
*                            NEVER APPEARED.
 HREJ     EQU    13          6681 REJECTED CONNECT FUNCTION 
 HSYN     EQU    14          SYNCHRONIZATION LOST.
 HLCR     EQU    15          LOST CONTACT WITH REMOTE SITE
 SCML     EQU    16          LINKCTL REQUEST TOO LONG 
 HRSD     EQU    17          MESS. CANNOT BE SENT CORRECTLY 
 HMLT     EQU    18          MESSAGE TOO LONG.
 HBCH     EQU    19          TOO MANY CONSECUTIVE BAD CHAR. 
************************************************************************
* /---   BLOCK      FUNC SOFT  00 000   76/10/14  13.31 
          TITLE  COMMAND CODES AND CONTROL CHARACTERS 
************************************************************************
* 
*         COMMAND CODES FROM -LINKCTL-. 
* 
************************************************************************
* 
 FASU     EQU    0           CHECK FOR STARTUP
 FRES     EQU    1           RESERVE DRIVER.
 FMES     EQU    2           SEND AND RECEIVE A MESSAGE 
 FREL     EQU    3
 FSTA     EQU    4           RETURN 311 STATUS
 FSTI     EQU    5           RETURN STATISTICS COUNTERS 
 FTST     EQU    6           RUN LOOP BACK TEST 
 FLTL     EQU    7           LOCAL TERMINAL MODE
 FRTL     EQU    10B         REMOTE TERMINAL MODE 
 FSIL     EQU    11B         UNUSED 
 FNTL     EQU    12B         NEW LOOPBACK TEST. 
* 
************************************************************************
          SPACE  4
************************************************************************
* 
*         CONTROL CHARACTERS
* 
************************************************************************
* 
 CEOD     EQU    30B         END OF DATA
 CEOB     EQU    31B         END OF BLOCK 
 CEOF     EQU    32B         END OF FILE
 CNAK     EQU    33B         NEGATIVE ACKNOWLEDGE 
 CACK     EQU    34B         POSITIVE ACKNOWLEDGE 
 CETM     EQU    35B         END OF TERMINAL MODE 
 CSYN     EQU    62B         SYNCH CODE 
 CMAX     EQU    77B         MAXIMUM CONTROL CHARACTER
* 
************************************************************************
          SPACE  2
************************************************************************
* 
*         PLATO REQUEST CODES 
* 
************************************************************************
 PKILL    EQU    1           KILL THIS PPU ROUTINE
 PKEY     EQU    2           PRESS A KEY ON LINKCTL 
************************************************************************
* /---   BLOCK      FUNC HARD  00 000   76/04/07  23.34 
          TITLE  6681 AND 311-B CODES 
************************************************************************
* 
*         6681 DATA CHANNEL CONVERTER CODES 
* 
************************************************************************
 DCSC     EQU    2000B       SELECT CONVERTER 
 DCDC     EQU    2100B       DESELECT CONVERTER 
 DCIC     EQU    1500B       INPUT CODE 
 DCOC     EQU    1600B       OUTPUT CODE
 DCMC     EQU    1700B       MASTER CLEAR 
 DCCS     EQU    1200B       CONVERTER STATUS 
 DCES     EQU    1300B       EQUIPMENT STATUS 
************************************************************************
          SPACE  4
************************************************************************
* 
*         311-B FUNCTION CODES. 
* 
************************************************************************
 BSTP     EQU    1           SELECT STOP
 BSND     EQU    2           SELECT SEND
 BRSY     EQU    4           RESYNC CODE. 
 BSAR     EQU    6           COMBINED SEND AND RESYNC CODE. 
************************************************************************
          SPACE  4
************************************************************************
* 
*         311 STATUS MASKS
* 
************************************************************************
* 
 MCPE     EQU    1000B       CHARACTER PARITY ERROR.
 MCRQ     EQU    2000B       CHARACTER REQUEST
 MCRD     EQU    4000B       CHARACTER READY
 MCST     EQU    2           CARRIER ON 
 MCPH     EQU    1           CHARACTER PHASE
 MCSR     EQU    4000B       ODD CHANNEL STATUS READY 
* 
* /---   BLOCK      INITIAL    00 000   78/02/06  10.58 
          TITLE  INITIALIZATIONS
* 
 INITIAL  SUBR
* 
* * *     READ CONTROL POINT STATUS 
          LDD    CP 
          ADN    STSW        READ CONTROL POINT STATUS
          CRD    CM 
          LDD    CM+C.CPEF
          NJP    DPP2        DROP PPU IF ERROR
* 
* * *     GET CALL STATUS WORD
          LDD    IR+3        READ STATUS WORD 
          LPN    37B
          STM    PU          SAVE RELATIVE ADDRESS
          SHN    12 
          ADD    IR+4 
          STM    PL          SAVE BOTTOM OF RELATIVE ADDR.
          CALL   ABS         CONVERT TO ABSOLUTE
          ZJP    INITE       JUMP IF OUT OF RANGE 
* 
* * *     PLANT ABSOLUTE ADDRESS OF CALL STATUS WORD
          PLANT  CM,PPST
* 
* * *     READ PPU CALL STATUS WORD 
          LOADCM PPST 
          CRD    CM 
          LDN    1           INDICATE PPU UP AND RUNNING
          STD    CM+4 
          LOADCM PPST 
          CWD    CM          REWRITE STATUS WORD. 
* 
* * *     FORM ABSOLUTE ADDRESS OF COMMUNICATION BUFFER 
          LOADCM PPST 
          ADN    2
          PLANT  CM,COMBF 
* 
* * *     PLANT ADDRESS USED FOR ECS TRANSFERS
          LOADCM PPST 
          ADN    22 
          PLANT  CM,TRNBF 
* 
* * *     INITIALIZE WAIT FOR CHARACTER READY STATUS COUNTER
          LDC    ALSEVEN
          STD    NC 
* 
* * *     INITIALIZE I/O CHARACTER COUNTS.
          LDN    0
          STD    DL 
          STM    SFLAG
          STD    ECSOFF 
          STD    BADC 
          STD    MODE 
          LDN    50 
          STD    FRCHK       TIME-OUT COUNTER FOR READING 
*                            FRAMAT STATUS
          LJM    INITIALX 
* 
* * *     ADDRESS OUT OF RANGE SENT AN ERROR CODE.
 INITE    BSS    0
          CALL   DFM,CMSG 
          LJM    DPP         DROP PPU.
* 
 CMSG     DIS    ,*(CLD)CM ADDRESS OUT OF RANGE*
* 
 PARTBLE  BSS    128         START OF PARITY TABLE
* 
*CALL     PLAPABS 
*CALL     PLAPDNM 
*CALL     PLAPEQN 
*CALL     PLAPPLN 
* 
 C=CH     TABLE  CHANNEL     3266 CHANNEL TABLE 
* 
 E=CH     TABLE  CHANNEL     311 EVEN CHANNEL 
* 
 O=CH     TABLE  CHANNEL     311 ODD CHANNEL
* 
 PPST     TABLE  CM          PPU CALL STATUS TABLE
* 
 COMBF    TABLE  CM          COMMUNICATION BUFFER TABLE 
* 
 TRNBF    TABLE  CM          ADDRESS USED FOR ECS TRANSFERS 
* 
          ERRNG  7777B-*     PP OVERFLOW
          END
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