Memory upgrade help with unixpc

[Robert L. Haar CS50]

In article <1991Feb15.030125.20383 at ra.src.umd.edu>, zafar at eng.umd.edu
(Sohail Zafar) writes:

|> I successfully upgraded the ram card to 2.0M and want to do the same for the
|> motherboard. BUT I don't have anymore patience left to pull out
another 72 ICs.
|> What I want to do is cut the 64K chips with a cutter and use 1M RAMS
by making
|> a small board and using jumpers from the motherboard to this daughterboard.
|> I will thus have to desolder only a fraction of the pins!  What I don't have
|> is the hardware manual (to be specific the scematic and circuit
diagram). I am
|> planning to use two 1Mx8 and two 1Mx1 chips, so I will have only four
chips for
|> 2.0M of memory.  I want the circuit diagram for the decoder chips.  I would 
|> appreciate if someone who has the hardware manual could send me a
copy of the
|> circuit diagram or lend me his copy of Hardware manual if living in the
|> Washington Metro area. 

I tried to e-mail a response, but it went to hellcat.eng.umd.edu, which
said that there was no such user as zafar at eng.umd.edu.

I think you have a hard task - not only intercepting the address decoding
and inserting you own circuits, but also the physical constraint of 
fitting a daughter board in the vertical space between the motherboard
and the metal cover plate.

I have the hardware manual and will copy the memory section for you.
It will be next week before I get to it.

BTW - your address is very familiar. I lived at 4331 Rowalt while
attend UofMd - Ph.D. in C.S. 1980.  


	Bob Haar  InterNet : rhaar at albert.cs.gmr.com 
	Computer Science Dept., G.M. Research Laboratories
DISCLAIMER: Unless indicated otherwise, everything in this note is
personal opinion, not an official statement of General Motors Corp.