These are the error codes that QDOSMSQ can return from a vectored utility, a Trap or from SuperBasic extensions.

Always check for errors

When writing assembler routines, it is always advised to explicitly check the value in D0.L for an error code. This is done quickest using :

        :
        trap    #n                ; Do the trap.
        tst.l   d0                ; Did it work?
        beq.s   all_ok            ; Yes, all is well

errors  :                         ; Handle errors here
        bra     kill_job          ; And exit the job, or code somehow.
        
all_ok  :                         ; Carry on from here if all worked.

Some traps and vectored utilities do not set the Z flag before returning which is why you have to do it. Well, actually, it’s not that they don’t set it but when you call a trap, the status register is stacked for the duration and restored at the end, so while D0 may have an appropriate error code in it, the Z flag’s state is unknown. A vector should always have correctly set the Z flag, so save some coding and execution time by simply checking the Z flag, as follows:

        move.w  <whatever>,a2     ; Get the vectored routine.
        jsr     (a2)              ; Do it.
        beq.s   vec_ok            ; All is well, skip error handler.

v_error :                         ; Handle errors here
        bra     kill_job          ; And exit the job, or code somehow.
        
vec_ok  :                         ; Carry on from here if all worked.

Error codes