Unix-PC memory upgrades
Jonathan Sadler
sadler at shorty.CS.WISC.EDU
Wed May 4 14:11:01 AEST 1988
In article <2951 at pasteur.Berkeley.Edu> c60b-dk at buddy.Berkeley.EDU (John Sasinowski) says:
>
> I know that the Unix PC's motherboard contains 72 64K DRAM's
>(which give it 512K memory). I have several questions:
>
> 1. Can the 64K DRAMs be pulled out and replaced with 256K
> DRAMs (thereby putting 2Mb on the motherboard) ?
Yes they can. There was a message posted to unix-pc.general on 19 Feb
describing this procedure. This procedure has been tested. If you
would like a copy of this message, I would be happy to mail it to you.
>
> 2. If the above upgrade is possible, what modifications to
> the system software is necissary for the computer to
> recognize the added memory? Will it interfere with the
> expansion ram?
Just a few jumpers....
>
> 3. Can you add chips to the 512K ram card to give it a full
> 2Mb?
Yes, this upgrade was reposted at the same time as the above program.
>
> 4. Are there any difficulties with the above modifications
> (eg, desoldering parts of the motherboard, adding jumper
> wires, etc.?
The above DOES NOT involve any "pin 15 on IC452 to pin 3 on IC403"
style jumpers. It does involve bridging a few solder pads. The
real problem involves the 72 chips. Thats 16 pins per chip...
1152 pins per motherboard/ram-card.... There is always the chance
that you will "lift" a trace and botch the board. People have
done this upgrade, but they were not novice soldering iron users.
>
>Thank you in advance.
>
>John Sasinowski
>c60b-dk at buddy.berkeley.edu.arpa
>
If you have any questions about the memory setup on the UNIX-PC feel free
to ask.
Jonathan Sadler
Computing Systems Labritory (CSL)
University of Wisconsin - Madison
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