60fps Video on a CGA? – The GlyphBlaster
5 days ago
- #CGA
- #hardware-hacking
- #retrocomputing
- The GlyphBlaster project modifies a CGA card by replacing its font ROM with a programmable ROM using a Raspberry Pi Pico 2, allowing it to function as a 1bpp framebuffer for streaming and overlaying graphics on text mode.
- It synchronizes with the video signal via VSYNC and uses PIO programs for handling font ROM reads, enabling high-speed video at up to 60fps, demonstrated with examples like Bad Apple streaming and interactive animations like a bouncing DVD logo.
- The system supports ROM passthrough by OR'ing the original font data with custom graphics using the Pico's internal pull-ups, allowing overlay without disrupting text mode usability.
- Interactive features include cursor tracking for a cat sprite that follows the cursor or light pen, inspired by classic desktop toys, and potential for screen-reading capabilities by tapping into address lines.
- Future revisions aim to eliminate the passthrough socket by emulating the font ROM entirely, enabling software fonts and animations, with a designed PCB for potential wider use as a Pico-powered add-on.