Date   : Tue, 17 May 1988 18:16:04 GMT
From   : amdahl!drivax!riddle@ames.arc.nasa.gov (Riddle)
Subject: Ithaca Intersystems 256KDR S-100 memory

I liked <898@pilchuck.Data-IO.COM>'s solution to the S-100 24-bit addressing
to the old Z80-bank switching kludge.  Ithaca Intersystems took a simular
approch, the CPU board had a simple MMU which provided 8 banks of 16 4K
memory address translation.  That's how MP/M and banked CP/M plus were
implimented to look like a banked system, while DMA was still 24-bit addresses.

BUT........I have an easier (better :-)) fix for you people with Cromemco or
Advanced Micro type CPUs.

I will provide you schmatics of a one chip addition to the 256K board, so that
it will read the bank switch lines from the S-100 bus.

.........BONUS........make board into 1 meg.............BONUS............

It will also show how add address decoding for using 256K mem chips, giving
you 1 meg capacity on the board.

I can't/won't character draw it here, so Email me your Postal address and I
will USMail a copy to you.
                                       Riddle
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