George Foot's VGA "Video Card" Fits on One Breadboard — Nearly — and Could Be the World's Simplest
Inspired by Ben Eater's "world's worst video card," Foot's design reduces the component count to a bare minimum.
George Foot has created what may very well be the world's most basic "graphics card," in the form of a component-reduced breadboard circuit inspired by Ben Eater's earlier VGA output circuit project.
"Inspired by Ben Eater's 'World's Worst Video Card' video, I wanted to see how low we could get the chip count, and whether it would fit on a single breadboard," Foot writes of his project. "It would have done, if I'd squeezed it in more tightly! The key simplification from Ben Eater's design is getting rid of all the logic for working out the sync signals and just storing that in the EEPROM instead, along with the image data. It has some effects on the output resolution options, but is very effective at reducing the chip count, making this a very accessible way to experiment and tinker with video output!"
"There were a lot of compromises to keep the IC count low, which means that if you want to extend the circuit, without worrying so much about IC count, there's a lot of low-hanging fruit. Things like increased resolution and better colour depth would be fairly easy to achieve using a second EEPROM and/or different timer logic. Even higher resolutions could be possible with some shift register magic. You could also experiment with a palette look-up EEPROM. It should be possible to replace the EEPROM with SRAM and interface it with a CPU — and if you're willing to cut a lot of corners and put up with some glitches, this should be possible without adding many more ICs."
The project is inspired by what Ben Eater suggested may be the "world's worst video card," a project to demonstrate how the signals from a Video Graphics Array (VGA) compatible graphics adapter work — a standard developed for IBM's PS/2 in 1987 and still used today when higher resolutions aren't necessary. Like Eater's original, Foot's implementation is compatible with home-brew microcomputers including Eater's own BE6502 design.
Full details, including schematics, EEPROM image, and Python scripts, can be found on the project's Hackaday.io page.