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

On Thu, May 18, 2017 at 5:25 PM, Johnny Billquist wrote: > RX50. And yes, I installed MicroVMS on a MicroVAX II in 1986. We got a MicroVAX I in late 1984 or early 1985 and later upgraded it to a MicroVAX II ($17K upgrade, IIRC). Our uVAX-II distro medium was TK50, but we kept

[Simh] ASTLVL

From page 6-6 of DEC STD 032 (the VAX architecture spec): "Execution of MTPR src, #PR$_ASTLVL with src<31:0> GEQU 5 results in UNDEFINED behavior. The preferred implementation is to cause a reserved operand fault." MicroVAX II, CVAX, and Rigel all conform to the preferred behavior, as does the

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

> On May 18, 2017, at 3:26 AM, Johnny Billquist wrote: > > On 2017-05-18 03:23, Paul Koning wrote: >> ... > >> Is MT_ASTLVL defined as a register where only the low byte has meaning? > > Seems like it was using even fewer than 8 bits... Looked like it was only 3 > bits. But

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

Johnny Billquist wrote: >However, this might be different on different CPU models, so I suspect this >should be applied with care. >He was testing VAX/VMS V4.5, which is pretty ancient. The models supported by >that version would probably only be the VAX-11 models. (And yes, I include the

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

Matt Burke 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

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

On 2017-05-18 03:23, Paul Koning wrote: On May 17, 2017, at 8:00 PM, Matt Burke wrote: On 18/05/2017 00:18, Johnny Billquist wrote: Hum. Do I remember wrong? I seem to remember that when you MOVB to a register, the value should be sign extended. So not just the low byte