qdosmsq:traps:trap_1:info

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qdosmsq:traps:trap_1:info [2008/06/25 12:20]
norman Errors now in a table.
qdosmsq:traps:trap_1:info [2008/06/25 12:21] (current)
norman A few minor changes to MT_INF.
Line 1: Line 1:
 +====== MT_INF/SMS_INFO ======
 +This trap returns information about the Operating System.
 +
 +^Call Parameters^^Return Parameters^^
 +|D0.B|$00|D0.L|Undefined. Ignore return value.|
 +|D1.L|Unused.|D1.L|Job id of current job.|
 +|D2.L|Unused.|D2.L|QDOS/SMSQ version as ASCII string - '1.03' for example.|
 +|A0.L|Unused.|A0.L|Address of system variables.|
 +
 +
 +===== Errors =====
 +
 +|No errors are returned by this trap.|
 +
 +===== Notes =====
 +  * All registers not shown above are not used on entry and are preserved on exit.
 +  * The returned address of the system variables in A0 is a 'throwback' to the old days of QDOS whereby they could live at any address in RAM. Then, they became fixed for a while at address $28000 (163,840) and now, the pendulaum has swung back again - with Minerva and so on, the system variables do indeed live in different places in RAM once more.
 +
 +===== Example =====
 +The example below shows the use of this trap call to obtain the address of the location of the system variables prior to some (unknown?) usage of that returned address.
 +
 +<code>
 +info    moveq   #0,d0           ; MT_INF
 +        trap    #1              ; Get system variables address into A0
 +        ...                     ; Do something here.
 +</code>
 +
  
  • qdosmsq/traps/trap_1/info.txt
  • Last modified: 2008/06/25 12:21
  • by norman