8K Memory PCB

What is it?

A PCB for an 8K Static RAM expansion for the HobbyPCB 65C02 SBC. The board can be addressed at any of the 8 × 8K blocks in the full 64K address space.

• Red link — selects which 32K block the 8K resides in
• Blue link — selects which 8K block within that 32K block

The top 4 links are active. From the top they select: X000–X7FF, X800–XFFF, Y000–Y7FF, Y800–YFFF.

Why did I make it?

I wanted to be able to use expansion RAM in some of my programs.

What makes it special?

A very simple and useable design. Slots into any position on the Backplane and is immediately accessible at the configured address.

Bill of Materials

Quantity	Part
1	74LS245
1	74LS139
1	74LS00
1	Toshiba TC5565 (or equivalent) 8K×8 SRAM
1	36-way right-angled header strip
1	2×8 header strip (only 2×4 used on this board)
1	3-way header strip
2	Jumper links

Images