Static Memory Systems - 64K RAM/EPROM Board
SMS called this board "The last Memory" board.
THELASTMEMORYwas a highperformance64K memory board for8 bit (only) S-100
systems. This board uses TMM
2016, MB8128, or equivalent static
RAM's. The use of static RAM eliminated the timing and reliability problems
associated with some dynamic RAM
boards (using DMA etc). The 2K by 8 architecture of these RAM's allowed high
density and low power consumption, a characteristic not foundin moststatic memories up
until that time. THE LAST MEMORY™
also accommodated 2716 type EPROM's in place of the RAM IC's with no
modifications.MixingRAM andEPROM the 2K by
8 static RAM and 2716 EPROM's are pin-for-pin
compatible and could be located at any position on this board.
However, caution had to be exercised when mixing RAMs and 2716a. The RAM's
supplied have an
access time of 150
nsec, allowing full speed operation
with many 6 MHz processors. High speed versions of the 2716 were notavailableandsince waitstatesarenotgeneratedby the board,
system speed was
limited by the speed of the 2716's
used. If high speed operation was required, the Harris semiconductor HM7617
bipolar PROM could be used in place of the 2716 EPROM. This was a 60 nsec part,
but it was notreprogrammable.
The board could be addressed on 64K boundary in the 24-bit address space.
The board responded to the Phantom line. However the board did not have
circuitry for 16-bit data transfers and so was limited in use (and demand) for
16 bit CPU's appearing at the time.
