PDP-11/05 (was: PDP-11/05 microcode dump?)
tom at figureeightbrewing.com
Mon Jun 14 11:14:17 CDT 2021
I'm not to the point of connecting serial yet, but I did see this page which will help me turn the
current loop to rs232 when the time comes:
On 6/14/21 10:37 AM, Jay Logue via cctalk wrote:
> I also have an 11/05 with the early CPU boards that exhibited stuck bits on arrival. Turned out
> to be bad transistors in the inhibit circuits on the G110. Pretty easy fix once I tracked it
> down. So far I've found the GT40 print set to be a fairly accurate, at least for the boards I have.
> I'll be curious to learn how your serial console works. Mine had a manufacturing defect that had
> to be corrected before input would work.
> On 6/13/2021 1:44 PM, Tom Uban via cctalk wrote:
>> I am working on the first of my two 11/05s. Interestingly, it has the early version M7261E Control
>> Logic & Microprogram board and the later version M7260 Data Paths board (with circular baud rate
>> selector switch) as described in:
>> From the description there, it seems like an older/newer combination, but maybe that was common. I
>> would not have guessed that the four possible combinations would all work together, but maybe
>> they do?
>> I have a couple different drawing sets for the 11/05 and while some have the matching M7260
>> schematic, only the GT40 drawings (I found on bitsavers) has the M7261E schematic:
>> The GT40 drawings has the PROM listings and related, so I am hoping that they match what is in the
>> two boards.
>> Presently, the machine sometimes runs relatively well and other times it does not. It does have bit
>> 1 stuck ON in memory, but that should be a relatively simple task to diagnose as it is not
>> intermittent. When the machine is "working" I am able to deposit 0777 at 0100 and run. When running
>> this simple program, I've experimented with flexing the boards and such, so it doesn't seem like an
>> obvious poor connection, but that remains to be seen.
>> The machine is a configuration #2 model (as described in the "gunkies" site) and my initial messing
>> with KM11 boards, reveals that I can step the microcode with a KM11 in either the #1 or #2 position,
>> but when two KM11s are installed at the same time, they do not function properly together. Is this
>> expected or do I have an issue there too?
>> Thanks much to those who have provided details and documents on the web, they have already been of
>> great value and will most certainly continue to be a resource in the future.
>> More updates in the future...
>> On 5/6/16 5:32 PM, Noel Chiappa wrote:
>>> > From: Mattis Lind
>>> > Thanks Noel for sorting this out.
>>> Eh, de nada. But thank you.
>>> >> I wonder if the ucode in the two versions is identical? The uROM chip
>>> >> numbers should give it, (if they are the same on both versions, albeit
>>> >> in different locations on the board), but I have yet to check. Does
>>> >> anyone happen to know?
>>> OK, so the situation here is pretty complicated. To start with / make things
>>> worse, that CPU uses lots of PROMs. Lots and lots and lots and lots of PROMs.
>>> For the data paths board (M7260), both major versions appear to contain the
>>> same PROMs (going by the DEC part numbers), but the chip location (Exx)
>>> numbers are all different.
>>> For the control board (M7261), the C, E ('early' version) and F ('late'
>>> version) etch revisions each contain mostly the same PROMs, but apparently
>>> with slight differences between the sets of PROMs in each (as reflected in
>>> different DEC part numbers). For details see:
>>> to which I have just added all the gory details.
>>> As to getting the contents of all of them dumped in machine-readable form -
>>> oi vey!
>>> >> on the earlier version (prints for that version are in the GT40 prints
>>> >> online
>>> It turns out that I have hard-copy prints for the "C" etch revision of the
>>> M7261, which do not yet appear to be online; the GT40 prints have the "E"
>>> etch revision.
>>> I will scan the pages for that revision of the board, and put them up 'soon'.
>>> (I'm not doing the whole print set, it's about 1" thick, and most of them are
>>> for other things anyway, like MM11-L memory, etc.)
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