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Seattle Computer Products -- (110A) 64K RAM Board

This was SCP's final RAM board. The board utilized Hitachi high speed HM6167 (16KX1) CMOS RAM chips. The equivalent Intel 2167 or NEC UPD4311 chips could be used as well.


This board met all the electrical and timing specifications for the IEEE-696 S-100 bus standard. It had a capacity of 64K bytes, but was available in 16K, 32K, and 48K versions to OEMs. The 16K and 48K versions were eight-bit only.  The memory itself was organization as 64K by eight bits. Sixteen bit transfers access two bytes simultaneously as specified by the IEEE-696 standard.

The board had extended 24-bit addressing but could be set to ignore upper eight address lines in systems with only a 64K address space. The board could start on any 64K boundaries in the S-100 16MB address space. 32K versions could be addressed on any 32K boundary.  High speed 100 nsec chips were normally used. Memory access time from pDBIN high (assuming address setup time has been met) was about 59 nsec.
A minimum of only 45 nsec. was required for the MWRITE pulse width.  The board did however suck down 2.5 amps when fully loaded.

The manual for this board can be obtained here.


Other Seattle Computer Products  S-100 Boards
8086 CPU   8086 Support Board   16K (24-101)RAM   16K (107A)RAM  16KRAM   64KRAM   Serial IO    DiskMaster


This page was last modified on 10/25/2013