Date   : Thu, 12 May 1988 17:08:00 -0600
From   : Ken Wallewein <kenw%noah.arc.cdn%ean.ubc.ca@RELAY.CS.NET>
Subject: Ithaca Intersystems 256KDR S-100 memory

  I have a couple of Ithaca Intersystems 256KDR S-100 memory boards which I'd 
really like to use. 512 kb would be rather nice, and there's more where they 
came from. 

  However, there's a wee problem. Or two.

     a) They use IEEE 696 24-bit addressing. Sounds great, right? Yeah, well,
how do you do Z80-style bank switching? I can put 8-bit addresses on those
lines, no problem. But HOW DO I KEEP A COMMON BANK? The Z80's going to want to
keep some memory common, to execute in, won't it? The only thing I can think
of is to hack up the board, moving the boards address bits 16 through 23 down
one where they connect to the bus, putting them on 15 through 22, and tying
the internal bit 15 low (I think). That would make everything show up in the
low 32k only. 
  
     Surely there's a better way...? 

     b) The docs I have for them are a bit deficient: no schematics, and there
are (is?) one dip switch and one jumper which are not even mentioned. 

  The boards are identified as 1119-03.

  If anybody could belp be out, I sure would appreciate it!

 /kenw
                                                                 A L B E R T A
Ken Wallewein                                                  R E S E A R C H
kenw@noah.arc.cdn                                                C O U N C I L

            ...I owe my soul to the company store...


End of INFO-CPM Digest
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