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: http://retrocmp.com/how-tos/interfacing-to-a-pdp-1105
--tom 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. > > --Jay > > 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: >> >> http://gunkies.org/wiki/KD11-B_CPU >> >> 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: >> >> http://www.bitsavers.org/pdf/dec/graphics/VT11/GT40_Graphic_Terminal_Engineering_Drawings_Feb73.pdf >> >> 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... >> >> --tom >> >> 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: >>> >>> http://gunkies.org/wiki/PDP-11/05#Control_PROMs >>> >>> 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.) >>> >>> Noel >>> >
