v1.0 Undergoing Testing and is Available on Tindie

A project log for SBC-85 1Mbit Memory Expansion Board

Offering any Combination of up to 128KB of ROM, up to 32KB RAM

CraigCraig 07/04/2020 at 21:510 Comments

Version 1.0 of the memory expansion board has been built and all preliminary tests indicate it is good to go.  As seen in the photographs, the first test configuration has a 2732 EPROM, two 2764 EPROMs, and a 6264 RAM.  For more complete testing, I need to do more mixing and matching and use all versions of EPROMs up to the 27256 in various combinations.  In this test I have the two 2764s mapped at the same address space in different pages and that works well.  Some nice features on this board even if I do say so myself.  The addressing seems confusing at first but I think it is straight forward once explained.  I guess we will see when I start to get feedback on the [so far non-existent] documentation.

As a first step in the documentation, I did start to put together the cheat sheet for the board to help keep track of how it is configured.