This is a 4K memory expansion board I created for the KIM-1, providing RAM from $0400 to $13FF. The circuit is very simple, with just two ICs, three caps, a resistor, and two connectors. I used a proto-board version of this for several years before deciding to make a real PC board so it looked professional.

I soon found other KIM owners wanted this board, so now I make them available as either a blank board, a kit, or full assembled. With the success of this board, I created an I/O board and am working on more projects. Buying a board will encourage my behavior!

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I wanted a better memory test to check out the boards, so this source code is available for free. It does a 9 bit pattern, which means the pattern repeats every 9 bytes, which makes it easier to detected shorted/open address lines. It's based on works of others, as you'll see in the comments The test continues to run until it detects an error or you press the RS button on the keypad. After each successful pass, it prints a simple "." to the TTY. If it finds an error, it will display the address, the value expected and the value read.

The memory can be selected 1K at a time using the KIM's K1, K2, K3 and K4 pins on the Application connector. Bringing all four to this board will give you contiguous memory from $0000 to $13FF (5K total). It's a very simple board, so it anything goes wrong, it's easy to figure out the problem. The blank boards are made by a professional shop not etched in my bathroom sink.

Don't Want To Build Your Own?

I offer the 4K memory board in three different forms:

Blank board: $25
Kit: $40
Assembled: $5

Each order also has a $5 S/H charge regardless of how many items were purchased.

All three include documentation and schematics. The assembled boards are tested for several hours prior to shipment. Generally speaking, blank boards ship the next business day. Kits or assembled boards usually ship in two days.