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From: jnw@mcnc.UUCP (John White)
Newsgroups: net.micro.trs-80,net.micro.pc
Subject: Re: A Cheap(er) Memory Upgrade for the Tandy 2000
Message-ID: <636@mcnc.mcnc.UUCP>
Date: Sat, 20-Jul-85 14:37:49 EDT
Article-I.D.: mcnc.636
Posted: Sat Jul 20 14:37:49 1985
Date-Received: Sun, 21-Jul-85 22:43:35 EDT
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Organization: Microelectronics Center of NC; RTP, NC
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Xref: linus net.micro.trs-80:245 net.micro.pc:4356

> Use 64k dynamic RAMs, 150 nanoseconds.  You need sixteen of them.
     The only external memory board I've seen needs eighteen chips. (Remember
parity) Also, I would use 120 nanosecond chips as the timing is pretty tight.
I upgraded my memory board by replacing the first row of chips with 256k chips.
This gave me a 512k memory board for a total of 768k (The other 256k is on
the motherboard). I did this because I didn't have any more slots for another
memory board. I used some unused gates and some uneeded gates to get the
extra address bit multiplexed properly. (The design of the memory board is
very sloppy and uses many more gates than it needs.) I wouldn't advise this
for the average user, but I don't see why Tandy doesn't come out with a
512k board.
- John N. White <mcnc!jnw>