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Fulcrum   Omniram  -  64K Static RAM

This was the first RAM board Fulcrum made themselves.  Up until then they just resold IMSAI boards. It came however after they made and sold their VIO video board.

Fulcrum 64K Static RAM

The board was completely IEEE-696 compatible and provided 64 kilobytes of fast static random access memory on the bus. Provision was made for 8 or 16 bit transfers, extended 24 bit addressing, and for control via the bus phantom line. In addition, a number of features were included to make the board compatible with systems that were designed before the IEEE-696 standard was developed. These included bank selection and provision for operation with IMSAI-type front panels. When the bank select option was activated, the board could be divided into two parts which could reside in two separate banks. The division of the board could be into two 32K sections or into one 16K section and one 48K section. Provision was made for DMA override of bank selection if needed. The board was also compatible with IMSAI-type extended addressing.

The board allowed several different 2K or 4K banks of memory  to be disabled and allowed EPROM (2716's) or RAM chips to exist in the system.  The board normally used M58735P static memory chips (Fulcrum got a good deal on a bulk purchase of the chips).  Presumably the board would also work with the more common HM6116's as well since they have the same pin-out.

There appears to be two version of the board. The manuals can be obtained here and here.  
Bill Machrone compared this board to some others in an article in the January 1983 issue of Microsystems (Vol 4, #1, p70).  It can be seen here.


Other Fulcrum  S-100 Boards
64K Static RAM      256K Static RAM      VIO Video Board     Omnidisk FDC


This page was last modified on 10/25/2013