just the Unfortunately not. I removed all the expansion cards, but it still complains about memory. It has a daughter card mounted on the main board (not in the expansion slots). The 350 has two cards that appear to be physically the same (connector wise), but different part numbers and different chips (I have not looked up their datasheets). It would be nice to try the 350 daughter cards in the 380, or vice versa, as neither machine works, but at the moment I don't really know why. Regards Rob

You should get the Pro 300 technical manual (two volumes) from Bitsavers. It contains a great deal of relevant detail. I misremembered the 350 (I don't have one): it can have memory in the I/O card cage, but it also has memory daughter cards, two of them, with 40 pin connectors. The Pro-380 has main memory on the motherboard. It also supports an optional expansion card, just one, with a 48 pin connector. The pinouts shown for the two types of daughtercards make it very clear that they are entirely incompatible. The Pro-380 also has graphics on the motherboard (though EBO is an option, via a daughtercard). So a Pro-380 with nothing in the I/O card cage should power up and give you a display on the screen (presumably one complaining about not having a bootable device controller...). On the other hand, the Pro 350 uses a graphics card in the I/O cage, and EBO is a second I/O card connected to the main one via a jumper cable. Neither of these is compatible with the Pro-380. I have somewhere a printout (on 11x17 size paper, roughly A3) of the Pro 380 motherboard schematics. I haven't seen those elsewhere. I haven't tried to scan them but try if there's interest. paul

It should EBO Neither Thanks, I see that now. Definitely no compatibility :-(. Just need that logic analyser really to work out what is the matter with them both. When the 380 doesn't have the daughter board installed it leaves all the LEDs on to indicate a system board error. The 350 has the same symptoms with or without the memory boards. Strange though that the manual mentions a standard option with memory on the backplane, I don't think my 350 had that installed. I also notice that the printer port can give access to ODT, I will see if I can get anything out of that later. 380 to

That would be a good thing. Also, from the "I can dream, can't I?" department would be the drawings for the HSC50 and 70 On 8/29/16 10:10 AM, Paul Koning wrote:

You're talking about the Pro-380 daughtercard, right? It has a jumper on the card to indicate to the software whether the card has 64k or 256k chips. I don't see anything like that in the Pro-350 description. The Pro 380 schematics have a tantalizing hint that the motherboard memory could be populated with 256k memory chips. At least that's what the "memory jumper configuration" note on sheet 4 of the PC380 system module schematics suggests. Nothing else explains further, though. The notes on the drawings also mention several different manufacturers, and the memory is described as "MOS memory ... 150 ns". It turns out the schematics I have are the "PC380 system module" portion of what's already on Bitsavers in MP01922_PC380_EngrDrws_Jun84.pdf -- same revision. The one extra bit of information is a hand-written note on the first sheet saying "these schematics match Rev E1 etch 03-MAY-84" paul

Yes, indeed. And the key item is shown on the daughtercard connector description: it has address lines 0..8, so 9 address bits, times 2 since DRAM has row and column addresses, that makes 256 k words. What's different compared to the 380 is that there doesn't appear to be a signal that says which chip size is present, unless it's that "reserved" pin 39. The Pro 30 has pin 43, P256KD L, in other words, "this pin is connected to ground if the card has 256k chips on it". I wonder if those memory chips are still available. Alternatively, I suppose one could emulate the whole daughtercard (the DRAM protocol and the memory too) in an FPGA. :-) paul

Another possibility would be a current (not surplus) DRAM device such as a 1M x 16 chip, plus a couple of level shifters to go between the 3.3 V it likes and the 5V logic of the Pro. paul

Yes, the one I saw when I made that comment is an MSM51V18165F by Lapis, a 1M by 16 "fast page mode" EDO DRAM. That would be interesting to try. paul

The ISSI memory calls itself "DRAM with fast page mode", it does not say "EDO". But judging from the timing diagrams (which show that data out turns off after the later of RAS and CAS deassertion) it sounds like "fast page mode" is a confusing way to say "EDO". Now the question becomes what the Pro actually does. I don't see it in the documentation or schematics, unfortunately. Incidentally, the Pro technical manual says that the daughterboard can be up to 2 MB (but DEC only offers 512 kB). It doesn't say how that is done. It looks like the answer is that there are four RAS signals, so you can have four banks, 256k by 16 each. paul

I was talking about the Pro 380, which has only one daughterboard. Still, 2.5 MB is not shabby. See page 6-25 in the technical manual. Then again: see also page 6-52 and 6-53, the memory config register. And the description on page 26 of the Pro 380 schematics. It says pretty clearly that you could use 256k DRAM on the motherboard, which (if you install all four banks) would mean 2 MB on the motherboard. Both motherboard and daughterboard have two wires to indicate bank count (1..4) and a "256 kB memory chips" signal as well, so both are in principle capable of being up to 2 MB each. What happens if you install 4 MB is not entirely clear, since the I/O page still has to go to I/O of course. A four bank "256k" daughtercard would be straightforward; I figure you could do it with a few gates plus a 1Mx16 memory chip -- give or take the EDO issue discussed earlier. Installing 256k memories in the motherboard of course is more of a job because you have to take the existing baord apart. The Pro 350 only has one RAS signal. Then again, the connector pinout (page 5-129) shows a "Bank" signal; I wonder what that means. Does anyone have Pro 350 schematics? paul

just the Manx has a pocket service guide that is specific to the 380, which might give me more info, but Manx seems to be in the process of being relocated, so I can't access the document. Does anyone have it? Regards Rob

I hadn't noticed until I tried to access it a week or so ago, because I have most of the manuals I need locally so I don't check Manx all that often. Is there any news on when it might be back though? Regards Rob