256K Dynamic RAM
This was quite an advanced card at a time when going past 64K memory in a
microcomputer was the norm. This board allowed the Z-100
Model 85-2653-1 computer, to go up to 768K of
RAM when these cards were used in a system. The motherboard of
course had to first have 192K of RAM.
The board utilized 64K X 1 dynamic RAM chips. It
could be addressed on any 64K boundary of the S-100's 16 MG address space.
There was parity bit error detection in hardware on the board. The board
utilized 200 nsec RAMs. The data path could be either 8 or 16 bits wide and
0,1,2 or 3 wait states could be inserted for data R/W. The board in
fact met all IEEE-696 specifications.
The (very detailed) manual for this board can be obtained
The schematic for the board can be obtained
Modification: To convert this 256K Dynamic RAM board to
a 1M Dynamic RAM board
Soon after the board came out a small adaptor board was made that allowed
this RAM board be converted from a 256K RAM board to a 1Mg RAN board.
The instructions as to how to do this are
Other Heathkit S-100 Boards
Winchester Disk Controller
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