MT_INF/SMS.INFO - System Information

This trap returns information about the Operating System.

Call Register Call Parameter Return Register Return Parameter
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.


No errors are returned by this trap. Ignore any value in D0 on return.


  • 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 pendulum has swung back again - with Minerva and so on, the system variables do indeed live in different places in RAM once more.


The example below shows the use of this trap call to obtain the address of the system variables prior to some (unknown?) usage of that returned address.

info    moveq   #SMS.INFO,d0    ; Or MT_INF.
        trap    #1              ; Get system variables address into A0
        ...                     ; Do something here with A0.