[Simh] Problem with MT_ASTLVL on the VAX-11/780

[Sergey Oboguev]

Matt Burke <matt at 9track.net> wrote:

> Whilst experimenting with a new device on VAX/VMS V4.5 I got a fatal
> bugcheck (exception whilst above ASTDEL). The problem turned out the be
> a reserved operand fault and I traced it back to the following code
> (shown here from the VMS 3.0 source listings):
> 
> MOVL    PCB$L_PHD(R0),R0        ; Get PHD address
> MOVB    PHD$B_ASTLVL(R0),R0    ; And fetch ASTLVL
> MTPR    R0,#PR$_ASTLVL          ; Update current value

FWIW, the sequence does not appear to be present in 3.7-dev, 4.0 or 7.3 sources.

(For 3.x and 4.x I checked only ASTDEL, not ASMP code -- speaking on which, would not it be fun to emulate 11/782 or 11/784?)

Is this exact sequence actually indicated by the instruction trace when running 4.5?

Thanks,Sergey
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