Swithable Eprom

[David A. Cooley]

At 11:17 PM 5/13/99 -0700, you wrote:
>I am a student and for a class project I am researching the best way to make 
>a switchable Eprom for a GM P-4 computer,  the normal Eprom is a 27c128, I 
>would like to have 10 different programs loaded for testing in back to back 
>conditions.
>
>If you could let me know the best way to do such a thing it would be 
>appreciated.  I did search the archive, but thought the information may have 
>changed since the 97 postings I found.

Ron,
I did this with 6 programs back in 93 on a S15 Jimmy.  Used a 27C1024 and
burnt the programs in order, IE prog 1 from 0 to 128K, 2 from 128K to 256K
etc.  Hooked the lower address lines and all the data/power etc to the ECM
like a 27C128.  The additional address lines I sent to a thumbwheel switch.
 Used it to select the lines so the ECM saw whatever 128K block I needed it
to see.  Could switch it while running down the road without a hiccup.
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           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
   Sponges grow in the ocean... Wonder how deep it would be if they didn't?!
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