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Jade Computer Products -   64K Dynamic RAM  Board
Jade called this board "The Memory Bank".

Jade 64K DRAM Board

The "MEMORY BANK" was a 64K dynamic RAM memory board. It could be used as a standard 8-bit wide memory board, or as a 16-bit by 32K memory board, either by a parallel transfer of 16 bits through a bidirectional gated data bus, or by a sequential transfer of a high byte and a low byte. In this, it follows the conventions established by IEEE Standard 696.

The board could be selected by port addressing per Northstar/Cromemco/Alpha Micro/SD Systems convention, or by using the full 24-bit extended address bus proposed by the IEEE standard. It was garunteed to be compatible with the following CPU products: SD Systems SBC-200,  Jades own "Big Z" CPU Ithaca Intersystems Z80-II board,  the Solid State Music CB2 Z80 board, the Cromemco ZPUTDL's  ZPU and the Northstar ZPB-A.

Although the board was designed specifically for use with Z80 and Z8000-type systems, it operated successfully with other CPU types that met the timing specifications of the S-100 bus and were capable of providing a memory-request signal similar to that of the Z80.  Its timing was designed such that it may be used up to 6 MHz with proper RAM chip selections and without board modification.

The board also provided an on-board M1 wait state generator and a unique RAM pre-charge extender which functions without adding wait states to the memory cycle, yet allows slower RAM chips to be used with 4 MHz and 6 MHz CPU chips.
The board performed its refresh cycles transparently to all CPUs and was capable of being used with DMA devices and disk controllers which utilize extended wait states.

Any 16K bank could be disabled by switch selection. In addition, special circuitry existed on the board that can deselect the top 4K or 8K of memory space, allowing its use with CPU types that have on-board EPROM monitor programs or boot programs without provision for disabling RAM memory when it is in conflict with the EPROM location.
The manual for this board can be obtained here.


Other Jade S-100 Boards
Bus Probe    Z80 CPU   64K RAM   FDC   1P2S   PSIO


This page was last modified on 10/01/2016