Type ASSEMBLE
Source Lines : 358
Fixes Applied : 5
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [R13219DS]

Module

       DMSITE

Function

     TO HANDLE EXTERNAL INTERRUPTS.

Attributes

     NUCLEUS, REENTRANT

Operation

       DMSITE USES THE WORKAREA EXISECT IN THE NUCLEUS IN
       ORDER TO MAINTAIN REENTRANCY.

       AN EXTERNAL INTERRUPTION CAUSES  CONTROL TO BE PASSED
       TO THE EXTERNAL INTERRUPT HANDLER DMSITE. IF THE
       INTERRUPT WAS  CAUSED BY THE  TIMER, BLIP IS  ON, AND
       THE CONSOLE IS QUIET, DMSITE RESETS THE TIMER TO A
       VALUE OF TWO SECONDS, AND TYPES THE BLIP CHARACTER AT
       THE TERMINAL.   THE STANDARD BLIP CHARACTER  IS UPPER
       CASE, FOLLOWED BY  LOWER CASE (IT MOVES  THE TYPEBALL
       WITHOUT PRINTING).

       IF  THE  INTERRUPT  WAS NOT  A  TIMER  INTERRUPT  AND
       EXTERNAL INTERRUPT  HANDLING IS  NOT WANTED,  CONTROL
       RETURNS  TO   THE  CALLER.   IF   EXTERNAL  INTERRUPT
       HANDLING IS WANTED, FREE STORAGE  IS OBTAINED TO SAVE
       REGISTERS,  THE  NEW  EXTERNAL  PSW  IS  LOADED.   ON
       RETURN, THE  REGISTERS ARE  RESTORED AND  THE STORAGE
       AREA RETURNED.  IF  THE OLD PSW WAS NOT  IN WAIT, THE
       OLD EXTERNAL PSW IS LOADED  AND CONTROL RETURNED.  IF
       IT WAS IN WAIT AND THE  INTERRUPT CODE WAS NOT AN I/O
       INTERRUPT, THE  RETURN ADDRESS IS  SET AS  ADDRESS IN
       EXTERNAL OLD PSW AND CONTROL IS RETURNED TO CALLER.

Calls to Other Routines

       FREE, FRET, CONWRITE