Vector Graphic 12K PROM/RAM III
Vector Graphic's PROM RAM III Board is a versatile, S-100 bus compatible,high density memory board combining the memory technologies of erasable programmable read only memories (EPROMs ) and high speed random access memory (RAM). Of unique value, one of the PROM sockets on the board can be used to program a 2708 or 2704 EPROM, enabling any owner to create PROM-based software for use on this board or in any other icroprocessor device. 1K of RAM is provided on the board, but no PROMs are included with purchase.
PROM/RAM III By combining the use of MSI decoding logic and unique addressing features, a wide range of applications requirements may be met by this memory board. The addressing flexibility is as follows. The board offers two independently addressable 8K blocks of memory (A and B). You use jumpers to specify the two separate 8K addressing spaces assigned to these blocks. Block A can be used for up to 8K of PROM. Block B contains 1K of on-board RAM plus up to 4K of PROM.
For block B, you use jumpers to specify whether the PROM is at the top or the bottom of the 8K allocation, and then, within the remaining 4K, where the 1K of RAM is addressed. Once this is done, there are also jumper options for DISABLING some or all of the remaininq 3K of addressing space allocated to block B, so that other boards in the system can use those addresses.
The addressing spaces are fully utilized if 2708 1K PROMs are used. If 2704 1/2K PROMs are used, then every other 1/2K of PROM allocation will be used, with 1/2K gaps between. Other features offered by the board are: jump on power-on or reset to on-board memory, with phantom generated to temporarily disable other memory boards, and a jumper option to use PRESET instead of POC to cause this jump, jumper option for on-board generation of the S-100 MWRITE signall and a jumper option to generate a one-cycle wait-state each time the board is addressed.
Full buffering of all inputs and outputs is provided to minimize loading of the system S-100 bus to at most one TTL load. On-board power regulation and filtering is provided using IC regulators and heat sinks for power dissipation. Careful attention to good design practice and an awareness of the need for flexibility has resulted in a reliable board useful in a wide variety of systems and applications.
12K PROM/RAM III Documentation
Prom-RAM-III pdf