PDP-11/34 CPU PROMS

[Warner Losh]

On Wed, Feb 9, 2022, 5:16 PM Rod Smallwood via cctalk <cctalk at classiccmp.org>
wrote:

> Hi
>
>      We have narrowed the problem down.
>
> Its the instruction decode ROM's that are the issue.
>
> The images of those are whats needed.
>

Do those chips have ROM numbers on them? 23-xxxxx is the usual format...

Warner

Regards Rod
>
>
> On 09/02/2022 23:14, Sytse van Slooten via cctalk wrote:
> >>>> On Tue, Feb 8, 2022 at 7:04 PM Warner Losh <imp at bsdimp.com> wrote:
> >>>> I found
> >>>>
> https://deramp.com/downloads/mfe_archive/011-Digital%20Equipment%20Corporation/08%20PDP-11/01%20PDP-1104-1134/05%20PDP-1104-1134%20Microcode/
> >>>> which has the source code...
> >>>>
> >>>> But I couldn't find the tools to use these files to create microcode
> >>>> images.
> >> Actually, the "m8266_ucode.v.txt" there seems to actually be the
> program that
> >> produced the symbolic dump (which is also available at:
> >>
> >>   http://www.bitsavers.org/pdf/dec/pdp11/1134/m8266_ucode.out.txt)
> >>
> >> It looks like the program is in VHDL or something like that, but it
> doesn't
> >> seem to have the actual microcode (was it stored/defined in another VHDL
> >> file?); that raises the question of where the actual microcode that it
> was
> >> dumping was.
> > It's Verilog (the 'other' hardware language besides VHDL), and indeed
> the rom images are in other files/modules - in some kind of straight binary
> format, I'd guess.
> >
> > I'm properly intrigued why someone would choose to do this - which seems
> to be mostly listing the microcode in a readable format - in Verilog.
> Unless of course it would be with a long term goal of using that microcode
> in an emulator that is sufficiently like a 'real' 11/34 to run it
> unchanged. I wonder if that is the case, and what became of the project -
> since the files are from 2014, it's probably safe to assume it got stuck
> somewhere along the way.
> >
> > Somewhere way down on my list of things to explore is something similar
> but then for the 11/70 - to make a vhdl version that is microcode
> compatible with the original, unlike the current pdp2011 that's 'only'
> functionally compatible. And this is about exactly the same way I would
> start - except I don't have the '70 rom images yet... If anyone has them
> and is willing to share, drop me a note ;-)
> >
> > Cheers
> > Sytse
> >
> >
>