PDP-11/34 CPU PROMS

[Jay Jaeger]

Looking at my inventory, I seem to have no less than four spare M8266 
(plus one in my 11/34 that runs, plus probably another in my 11/34 out 
in the garage.)

Rod, where are you located?

JRJ

On 2/9/2022 6:16 PM, Rod Smallwood via cctalk 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.
> 
> 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
>>
>>