Recent content by alitel

Hi folks -- just performing a resurrection of a very old thread here :) I wanted to document and share my recent experiments with ccpm-86 on a DEC Rainbow 100B. CCPM, in many ways, is pretty cool on the Rainbow. you can have up to 4 consoles active, so it seems there's some proper...

Hi there -- I gave the A19 "being maybe pulled high" issue a try yesterday by grounding out the A19 pin on the card connector to force it low, but it made no difference. So.... at this point, I'm going to take a pause on trying things -- I'm really not sure where the issue lies and I'm just...

Apologies -- I've attached the datasheet here, with the entire truth table. (What I provided was an excerpt of the most relevant rows, with the headings modified to describe our use case) Thank you for the shared memory explanation -- I didn't realize that this is what was being talked about (I...

Hi there -- OK, so yesterday I did some testing and poking around. I had built a little fixture to allow me to mess with the outputs of E104 without extensive resoldering (I've included pics as attachments -- note the appropriately rainbow cables used :)) I had started by taking a look at the...

Hi there -- I got the board socketed (15 of 16 pins were co-operative lol; the ground pin was NOT). All still in working condition. I added the modification connecting pin 24 of E87 to pin 8 of E72 and cut pin 8s ground connection. Unfortunately my result was poor -- scrambled video flowing...

Hi all -- I have the 100A board back out and will try to solder in the socket tomorrow (it's Tuesday night here now, Toronto Canada). I will also take pics of my motherboard and I will take pics of the 100A memory adapter. I will also see if I can trace continuity from E104 pins 12-14 through...

Hi na103! I'm glad you're joining the discussion, the more the better :) If you ask me, a modern re-engineering of the Rambow (lol) would be amazing. The only thing, it seems to me, that really limits the 100A is the memory size, and the only thing causing that is a scarcity of the OG solutions...

Oh, the bodge wire on the back of the 100B expansion card was me grounding pin 29. As I mentioned before, I wasn't able to find anything on the board pin 29 was connected to, which seemed odd to me -- I was expecting some kind of pull-up resistor type connection to enforce logic high. It may...

Hi! Thank you for the comprehensive reply! (I very much appreciate it) I agree that it might be best to socket E104 and go from there, so that's what I will likely do -- I do have some desoldering experience BUT I find with (well made and thick) boards like IBMs etc getting enough heat into...

Hi there -- I found time today to try out the initial mods to get the 100A to 512k. Sadly, I've not been able to get it working yet. I've re-routed the IO/M signal to header pin 30 (I have continuity back to the 8088) and connected pin 11 on E104 to header pin 43, removing the connection to pin...

Thank you! This is fabulous! I would like to try to enable the 512k option first, as being simpler from a rework point of view. If I can get that working, I'll work on reconnecting A19. My understanding of the procedure for the 512k mod so far is (please correct me if I've misunderstood): a)...

Thank you also for this! I do see an expired listing on ebay for one of these. I will add the part numbers to my ebay saved searches! Cheers! A

Thank you for this! I've got a copy of the technical manual addendum and will work away on wrapping my head around the memory expansion function. At a first read, I see what you mean that the 100B switches the meaning of 3 pins on the connector (as well as the NONSHRCYC pin difference) to use...

Hi there -- hey, that's brilliant news! I'm happy to do some reworking on the card and/or board -- I could try the simpler 500k mod first and go from there. Would you be ok to share the specifics of the lead that has to be wired for the simpler expansion? (And/or is there a schematic or...

Hi Nicola, Resurrecting an old thread here -- I just had it explained to me how this works on a 100A -- I am EXTREMELY keen to acquire one of these 8087 adapter boards, so am now on the hunt. If I do find one, I'd be more than happy to provide any information you wish if you still want to...