A $5 Graphics Card For Homebrew Computers


While not very popular, building a homebrew computer can be a fun and rewarding process. Most of the time, though, the video capabilities of these computers is as bare bones as it can get – running headless, connected to a terminal. While this is an accurate reproduction of the homebrew computers of the 1970s and 80s, there’s a lot to be said about a DIY computer with an HDMI-out port.

[spencer] built a Z-80-based homebrew computer a few years ago, and while connecting it to a terminal was sufficient, it was a build that could use a little more pizzazz. How did he manage to stuff a terminal in a tiny project box? With everyone’s favorite five dollar computer, the Raspberry Pi Zero.

The computer [spencer] built already had serial inputs, outputs, power, and ground rails – basically, a serial port. The Raspberry Pi also has TX and RX pins available on the 40-pin header, and with a stupidly simple board that [spencer] whipped up in KiCad, he could plug a Pi into the backplane of his homebrew computer. A few setup scripts, and a few seconds after turning this computer on [spencer] could mash a keyboard and wail away on some old school BASIC.

This isn’t a use case that is the sole domain of the Pi Zero. A Parallax Propeller chip makes for a great video terminal with inputs for PS/2 keyboards and mice. A largish AVR, with the requisite NTSC video library, also makes for a great video interface for a homebrew computer. The Pi Zero is only five dollars, though.


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The Raspberry Pi Zero contest is presented by Hackaday and Adafruit. Prizes include Raspberry Pi Zeros from Adafruit and gift cards to The Hackaday Store!
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