PIC Retrocomputer Boasts VGA, PS/2 Keyboard

You might think that our community would always strive to be at the cutting edge of computing and use only the latest and fastest hardware, except for the steady stream of retrocomputing projects that appear. These minimalist platforms hark back to the first and second generation of accessible microcomputers, often with text displays if they have a display at all, and a simple keyboard interface to a language interpreter.

Often these machines strive to use the hardware of the day, and are covered with 74 logic chips and 8-bit processors in 40-pin dual-in-line packages, but there are projects that implement retrocomputers on more modern hardware. An example is [Sebastian]’s machine based upon a couple of PIC microcontrollers, one of which is an application processor with a PS/2 keyboard interface, and the other of which handles a VGA display interface. The application it runs calculates whether a 4-digit number is a prime and displays its results.

His write-up gives a fascinating overview of the challenges he found in creating a reliable VGA output from such limited hardware, and how he solved them. Though this one-sentence description makes a ton of work sound easy, horizontal sync pulses are generated as hardware PWM, and pixel data is streamed from the SPI bus. The VGA resolution is 640×480, upon which he could initially place a 10×10 block of text. Later optimizations extend it to 14×14.

Sometimes it’s not the power of the hardware but the challenge of making it perform the impossible that provides the attraction in a project, and on this front [Sebastian]’s retrocomputer certainly delivers. We’ve featured many other retrocomputers before here, some of which follow [Sebastian]’s example using modern silicon throughout, while others mix-and-match old and new.

11 thoughts on “PIC Retrocomputer Boasts VGA, PS/2 Keyboard

  1. “You might think that our community would always strive to be at the cutting edge of computing and use only the latest and fastest hardware, except for the steady stream of retrocomputing projects that appear.”

    How many here are rocking a quantum computer?

  2. He even got CRT to match his creation, pretty sweet.
    Especially impressive when you read his post and realize PICs used are some janky (even more than ordinary PICs, seriously who below 40yr old uses PICs?) low power low resource versions!

    1. I still see PICs in the wild. They’re often used for appliances like microwave ovens where low MIPs is fine and there is no limit to the power budget. They’re easy to program in your favourite abstraction or even easy to program in assembly because the low end 8-bitters have about 35 instructions. RRISC – Really Reduced Instruction Set

      1. Why? did you receive a hand me down devkit and was too lazy to seek alternatives? work in a corporation with tons of legacy products? educated on PICs by some old farts (sorry Bruce Land :P)?

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