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

[Matt Burke]

On 18/05/2017 09:11, Sergey Oboguev wrote:
> 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

Actually this is the ASMP code :)

The file is [MP.LIS]MPINT.LIS and I think this instruction sequence is
present from VMS 3.0 to 4.7

Matt
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