MicroVAX I

From: Brian Chase <vaxzilla_at_jarai.org>
Date: Sun Jan 11 18:38:06 2004

On Sun, 11 Jan 2004, Antonio Carlini wrote:

> > I just noticed something for the first time in my VARM.
> > According to table 11.1, the MicroVAX-I supports the VAX's
> > PDP-11 emulation mode. The only other models that also
> > support this are the 11/7xx series, the 82xx, 83xx, and 86xx
> > systems--and they're all rather larger than a MicroVAX-I.
>
> My VARM states, on page 378 (in Appendix B, if you have a
> different version) that the uVAX I does NOT have PDP-11
> compatibility mode.
>
> Mine's the 1987 version that has Figure 11.1 but no
> Table 11.1. Chapter 11 is "Architectural Subsetting".
>
> Regardless of what any book says, I'd be stunned if
> they squeezed compatibility mode into the uVAX I.

Me too. I've got the 1991 version of the book. Table 11.1 on page 417
lists both the MicroVAX-I/D and MicroVAX-I/G as having support for
PDP-11 mode. I did misread the lines for the 82xx and 83xx processors;
it's only the 86xx series which have them.

So one of those versions of the VARM is wrong about the MicroVAX-I,
I'm guessing it's probably mine. I suspect this because, at the back
of the same book on page 538, under the B.2.6 MicroVAX-I heading, it
states, "The MicroVAX-I processor includes some of the optional string
instructions (CMPC3, LOCC, SCANC, SKPC, and SPANC) but does not include
any of the optional processor registers or PDP-11 compatibility mode."

-brian.
Received on Sun Jan 11 2004 - 18:38:06 GMT