CHIP-8 and the Pocket Mini Computer

Everyone who follows my Instructables and projects knows that I tend to be stuck in the 80s.

This time I'm setting the time machine for the year 1977, when the average monthly rent as $240.00 and a gallon of gas was 65 cents. Jimmy Carter was the president of the United States, and while home computers were available, they were a pretty big investment. The Apple II with 48k of ram would set you back $2,638.00 (That around $9,065.66 today!)

Geeks longed for their own computers, this where the COSMAC VIP comes in. It arrived in kit form costing only $275.00.

This Instructable will teach you how to build your own CHIP-8 compatible computer using the Pocket Mini Computer. I'll even show you how to build your own 4x4 keypad controller. (The game controller of the 70's)

Project Requirements:

The Pocket Mini Computer (See page 2 for more information)
If you choose to "roll your own" PMC configuration, you'll need to duplicate the VGA, SD, AUDIO, and SRAM circuits)

Parts for the DIY 4x4 keypad:

16 Tact Switches
A 5x7cm perf board
2 - 4.7k resistors
1 - PCF8574A IC
1 - Solderless mini breadboard
Wire/Solder/Soldering Station
A quiet, well-lit place to work

If you need a single source for all the parts for this project, I've got them in-stock at Propellerpowered.com

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Step 1: The RCA COSMAC VIP

Let me introduce you to the RCA COSMAC VIP, The DIY "kit" computer of 1977.

Check out these "cutting edge" specs!

Model: VP-111
Year: 1977
Price: US$275 (in kit form)
CPU: RCA CDP1802 @ 1.76MHz
Memory: 2048 byte RAM, 512 byte ROM
Interface: 16-key "hex" keypad
Display: composite video, 64x32 pixels
Ports: audio, video, cassette, parallel
Storage: optional external cassette
OS: RCA "CHIP-8" language

This machine arrived pretty much like the Pocket Mini Computer kit does today. A package of parts!

The image on this page is an assembled unit. The keyboard isn't missing! It's that 4X4 keypad you see in the corner of the unit! The VIP was programmed in a type of "Interpreted_language" called CHIP-8. Fortunately, the COSMAC VIP was quite a bit more advanced than many of it's predecessors, it connected to a TV as it's video display. It came with 20 games, but you had to type them in to play them.

I'll spare you all that typing with our PMC version of the COSMAC VIP.