PDP-11/34 CPU PROMS

[Rod Smallwood]

Hi

  Thank you all for your kind and quick replies.

I am sure somebody will come up with the actual images either the 
original files or derived from what we have.

As the key to the function of the 11/34 CPU their addition to the body 
of informatio they will be of imense benefit to us all.

Rod


On 09/02/2022 14:02, Noel Chiappa via cctalk wrote:
>      >>> On Tue, Feb 8, 2022 at 6:18 PM Rod Smallwood wrote:
>
>      >>> On the M8266 CPU control board a defective 7404 (E111) has killed a
>      >>> bunch of the PROMs holding the microcode.
>
> That's pretty astonishing; I've heard of PROMs dropping bits over time, but
> I'm a bit amazed to hear of a failure in a TTL gate (the 74S04 is a hex
> inverter; its gates are on pg. 7 of the M8266 prints - they produce uPC03-08)
> taking out a bunch of other gates connected to it.
>
>
>      >> 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 might be worth inquiring of Mike Douglas (he runs the DeRamp site) to find
> out where the files in "mfe_archive" came from; perhaps the source has, or
> knows of, the file which "m8266_ucode.out.txt" was a symbolic dump of - maybe
> from a complete KD11-EA simulation in VHDL?
>
> If that's not possible,it would be trivial to extract the PROM contents
> (well, partial contents - see below) from the "m8266_ucode.out.txt" file;
> each uword entry starts with the lines:
>
>    ***** PDP-11/34a micro code word for MPC = 000 *****
>    (MSB is left, indented fields generated by expansion ROMs)
>    micro word........ = 0000 0111 1100 0000 1100 1000 1010 0001 0000 0000 1110 0000
>             from ROM: E105 E103 E104 E100 E98  E97  E99  E106 E107 E108 E109 E110
>
> The address of each uword is the "MPC = xxx" line; the contents of the 12
> PROMs, at that address, are given on the "micro word........ = " line (the
> PROMs are 4 bits wide).
>
> If someone explained what format they needed as input for burning new PROMs,
> I could easily (like an hour) write a small portable program (using StdIO
> only, so it could be compiled and run on _anything_) that read that file in,
> and spat out the 12 PROM files. (Most of the dump could be ignored - all the
> data that's needed is in that one line.)
>
>
> BUT (and this is why it would be good to get back to the source of that file),
> that's not a complete M8266 ucode PROM dump.
>
> The KD11-EA has a uword address space 1 bit larger than the KD11-E - almost
> certainly to support floating point instructions; the KD11-EA adds 'uPC 09'
> (although looking its source at the top of pg. 7 of the prints, I don't quite
> grok how it is generated - maybe it's fed back through J2 from the FP11-A when
> one is plugged in). Anyway, uword addresses run up to 02000 in the KD11-EA,
> and the last uword in that dump is 0777.
>
> Interestingly, according to the flow charts of the 'basic' KD11-E/EA ucode in
> the prints (indexed and annotated here:
>
>    https://gunkies.org/wiki/KD11-E/EA_microcode
>
> in full), they stop at 0757 - but the dump (in "m8266_ucode.out.txt")
> contains uwords that are 'supposed' to be blank (per the flow charts),
> as well as above 0757.
>
> So that dump must have been prepared from a copy of the 'new' KD11-EA PROMs -
> the ones including the floating point ucode. (Note that the FP11-A _also_
> contains ucode, intended to control the stuff on the FP11-A; but the floating
> point instructions _also_ use the KD11-A for some stuff - e.g. fetching
> operands from main memory. Only the ucode address space is shared.)
>
>
>      > From: Warner Losh
>
>      > There's a small chance that the tools.tar.gz link on
>      > http://www.ak6dn.com/PDP-11/M9312/ has these, but that's for a
>      > different module so who knows.
>
> Right, a _completely_ different card - a boot PROM, not a CPU; totally
> un-related - and by a different person (Don North).
>
> But just for completeness, I looked in "tools.tar.gz", and it's just
> bootstrap PROM stuff.
>
> 	Noel