DISPLAY CP Privilege Class G
Use the DISPLAY command to display the following virtual machine components at
your terminal:
o Virtual storage locations (1st-level virtual storage only; see Usage notes)
o Storage keys
o General registers
o Floating-point registers
o Control registers
o Program status word (PSW)
o Channel address word (CAW)
o Channel status word (CSW).
Note: Use the NETWORK DISPLAY command to display the content of 3704/3705
storage.
The format of the DISPLAY command is:
+----------+------------------------------------------------------------------+
| Display | [[0|[K|L|T]hexloc1 [[[- :][END hexloc2]]|[[.][END bytecount]]] |
| | Greg1|Yreg1|Xreg1 [[[- :][END reg2]]|[[.][END regcount]]] |
| | Psw |
| | CAW |
| | CSW |
+----------+------------------------------------------------------------------+
where:
0 | hexloc1 | Lhexloc1 | Thexloc1 | Khexloc1
is the first, or only, hexadecimal storage location that is to be
displayed at the terminal. If L or no letter prefix is specified, the
storage contents are displayed in hexadecimal. If T is specified, the
storage contents are displayed in hexadecimal, with EBCDIC translation
beginning at the next lowest X'0' address. If K is specified, the
storage keys are displayed in hexadecimal.
If hexloc1 is not on a fullword boundary, it is rounded down to the
next lower fullword.
If L, T, or K is entered either without any operands, or followed
immediately by a blank, the contents of all storage locations or all
the storage keys are displayed. The address, hexloc1, may be 1 to 6
hexadecimal digits; leading zeros are optional.
0 is the default storage location.
- | : END hexloc2
is the last of the range of hexadecimal storage locations whose
contents are to be displayed at the terminal. Either a - or a : must
be specified to display the contents of more than one location by
storage address. If - or : is the first character of the operand,
then hexloc1 defaults to zero. If hexloc2 is not specified, the
contents of all storage locations from hexloc1 to the end of virtual
storage are displayed. If specified, hexloc2 must be equal to or
greater than hexloc1 and within the virtual storage size. (See Usage
notes for a discussion on discontiguous saved segments.) The address,
hexloc2, may be from 1 to 6 hexadecimal digits; leading zeros are
optional.
[.] END bytecount
is a hexadecimal integer designating the number of bytes of storage
(starting with the byte at hexloc1) to be displayed at the terminal.
The period (.) must be specified to display the contents of more than
one storage location by bytecount. The sum of hexloc1 and bytecount
must be an address that does not exceed the virtual machine size.
(See Usage notes for a discussion on discontiguous saved segments.)
If this address is not on a fullword boundary, it is rounded up to the
next higher fullword. The value, bytecount, must have a value of at
least 1 and may be from 1 to 6 hexadecimal digits; leading zeros are
optional.
Greg1 is a decimal number from 0 to 15 or a hexadecimal integer from 0 to F
representing the first, or only, general register whose contents are
to be displayed at the terminal. If G is specified without a register
number, the contents of all the general registers are displayed at the
terminal.
Yreg1 is an integer (0, 2, 4, or 6) representing the first, or only,
floating-point register whose contents are to be displayed at the
terminal. If Y is specified without a register number, the contents
of all of the floating-point registers are displayed at the terminal.
Xreg1 is a decimal number from 0 to 15 or a hexadecimal number from 0 to F
representing the first, or only, control register whose contents are
to be displayed at the terminal. If X is specified without a register
number, the contents of all of the control registers are displayed at
the terminal. If Xreg1 is specified for a virtual machine without
extended mode operations available, only control register 0 is
displayed.
- | : END reg2
is a number representing the last register whose contents are to be
displayed at the terminal. The dash (-) or colon (:) following reg1 is
used to specify a range of register values to be displayed. If reg2
is not specified, the contents of all registers from reg1 through the
last register of this type are displayed. The operand, reg2, must be
equal to or greater than reg1. If Greg1 or Xreg1 is specified, reg2
may be a decimal number from 0 to 15 or a hexadecimal number from 0 to
F. If Yreg1 is specified, reg2 may be 0, 2, 4, or 6. The contents of
registers reg1 through reg2 are displayed at the terminal.
[.]END regcount
is a decimal number from 1 to 15 or a hexadecimal number from 1 to F
specifying the number of registers (starting with reg1) whose contents
are to be displayed at the terminal. If the display type G or X is
specified, regcount can be a decimal number from 1 to 15 or a
hexadecimal number from 1 to F. If display type Y is specified,
regcount must be 1, 2, 3, or 4. The sum of reg1 and regcount must be
a number that does not exceed the maximum register number for the type
of registers being displayed.
Psw displays the current virtual machine PSW (program status word) as two
hexadecimal words.
CAW displays the contents of the CAW (channel address word at hexadecimal
location 48) as one hexadecimal word.
CSW displays the contents of the CSW (channel status word at hexadecimal
location 40) as two hexadecimal words.
Usage notes:
1. First level storage (storage that is real to the virtual machine) can be
displayed. Operating systems running in a virtual machine such as DOS/VS
and OS/VS have virtual storage of their own. This second-level virtual
storage cannot be displayed directly. The user or the virtual operating
system is responsible for converting any third-level storage locations to
second-level storage locations before issuing the command.
2. If a command line with an invalid operand is entered, the DISPLAY command
terminates when it encounters the invalid operand; however, any previous
valid operands are processed before termination occurs. Multiple storage
locations, registers, and control words can be displayed using a single
command line.
3. When multiple operands are entered on a line for location or register
displays, the default display type is the same as the previous explicit
display type. The explicit specification of a display type defines the
default for subsequent operands for the current display function. Blanks
are used to separate operands, or sets of operands, if more than one
operand is entered on the same command line. If a dash or a colon is
omitted between the hexloc1 and hexloc2 operands, and the two operands are
separated by one or more blanks, CP only displays the storage contents at
those two specific addresses. Blanks must not be used to the right or left
of the range or length delimiters (: or - or .), unless the user wants the
default value of the missing operand defined by the blank. For example:
display 10 20 T40 80 G12 5 L60-100
displays the following, respectively:
hexadecimal location 10
hexadecimal location 20
hexadecimal location 40 with EBCDIC translation
hexadecimal location 80 with EBCDIC translation
general register 12
general register 5
hexadecimal locations 60 through 100
4. To terminate the DISPLAY function while data is being displayed at the
terminal, press the attention key (or its equivalent). When the display
terminates, another command may be entered.
5. The DISPLAY command does not distinguish between shared and nonshared
storage; it displays any of the virtual machine's addressable storage
whether shared or not.
6. Use the DISPLAY command to display the contents of various storage
locations, registers, and control words at the terminal. By examining this
type of information during the program's execution, you may be able to
determine the cause of program errors. Usually, an address stop is set to
stop the program execution at a specified point. The system enters the CP
environment and you may then issue the DISPLAY command.
7. When you must examine large portions of storage, use the DUMP command
rather than the DISPLAY command. Because the terminal operates at a much
slower speed than the printer, only limited amounts of storage should be
printed (via the DISPLAY command) at the terminal.
8. When running with a discontiguous saved segment (DCSS), you can display
storage locations outside the range of your virtual machine size if they
are within the DCSS. If there exist locations between the upper limit of
your virtual machine and the address at which the DCSS was saved, an
attempt to display those locations (or associated keys) results in a
"nonaddressable storage" message.
Responses
One or more of the following responses is displayed, depending upon the
operands specified.
Displaying Storage Locations
xxxxxx word1 word2 word3 word4 (key) *EBCDIC TRANSLATION*
This is the response you receive when you display storage locations; xxxxxx
is the hexadecimal storage location of word1. Word1 is displayed (word-
aligned) for a single location specification. Up to four words are
displayed on a line, followed, optionally, by an EBCDIC translation of those
four words. Periods represent nonprintable characters. Multiple lines are
used (if required) for a range of locations. If translation to EBCDIC is
requested (Thexloc), alignment is made to the next lower 16-byte boundary;
otherwise, alignment is made to the next lower fullword boundary. If the
location is at a 2K page boundary, the key for that page is also displayed.
Displaying Storage Keys
xxxxxx TO xxxxxx KEY = kk
This is the response you receive when you display storage keys; xxxxxx is a
storage location and kk is the associated storage key.
Displaying General Registers
GPR n = genreg1 genreg2 genreg3 genreg4
This is the response you receive when you display general registers; n is
the register whose contents are genreg1. The contents of the following
consecutive registers are genreg2, genreg3, and so on. The contents of the
registers are displayed in hexadecimal. Up to four registers per line are
displayed for a range of registers. Multiple lines are displayed if
required, with a maximum of four lines needed to display all 16 general
registers.
Displaying Floating-Point Registers
FPR n = xxxxxxxxxxxxxxxx .xxxxxxxxxxxxxxxxx E xx
This is the response you receive when you display floating-point registers;
n is the even-number floating-point register whose contents are displayed on
this line. The contents of the requested floating-point registers are
displayed in both the internal hexadecimal format and the E format. One
register is displayed per line. Multiple lines are displayed for a range of
registers.
Displaying Control Registers
ECR n = ctlreg1 ctlreg2 ctlreg3 ctlreg4
This is the response you receive when you display control registers; n is
the register whose contents are ctlreg1. The contents of the following
consecutive registers are ctlreg2, ctlreg3, and so on. The contents of the
requested control registers are displayed in hexadecimal. Up to four
registers per line are displayed. Multiple lines are displayed if required.
Displaying the PSW
PSW = xxxxxxxx xxxxxxxx
The contents of the PSW are displayed in hexadecimal.
Displaying the CAW
CAW = xxxxxxxx
The contents of the CAW (hexadecimal location 48) are displayed in
hexadecimal.
Displaying the CSW
CSW = xxxxxxxx xxxxxxxx
The contents of the CSW (hexadecimal location 40) are displayed in
hexadecimal.