Unix-PC memory upgrades

[Jonathan Sadler]

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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