janfrombelgium/japi-base

Japi Base is a small homemade retro computer built around a Raspberry Pi Pico 2, which is a low-cost microcontroller board with a chip called the RP2350. The author wires the Pico to a VGA monitor, a PS/2 keyboard, a micro-SD card, and a pair of speakers, then provides the software that drives all of that. The result behaves like a tiny 1980s style computer, and the project is presented as both educational and genuinely usable. On the screen it produces a VGA picture at 1024 by 768 pixels and 60 Hz. The default mode is text with 127 columns and 64 rows, drawn in an 8 by 12 pixel font from the classic CP437 character set, with 64 colours for both letters and backgrounds. A bitmap window can be overlaid on top of the text for graphics, capped at about 128 KB of video memory, which is enough for a near-full-screen 832 by 624 image at double scale. For input and storage, a PS/2 keyboard with pluggable layouts (AZERTY, QWERTY, QWERTZ) is read through a logic level shifter. Storage offers a 360 KB LittleFS flash partition that acts like a built-in floppy disk drive (drive A), plus an optional micro-SD card (drive C) read through SPI. Audio comes out as stereo PWM through a simple resistor and capacitor filter, with a built-in four-channel wavetable synthesizer that supports ADSR envelopes, volume, and pan. The central design idea is that one CPU core and one PIO block handle all the input and output work, while the second core and the remaining peripherals stay free for the user's own code. The repository ships a ready-made firmware file that can be copied onto the Pico in BOOTSEL mode to run a demo: a colour palette, a bouncing ball animation, a dithered version of Van Gogh's Starry Night, and a live API reference. A code editor and a BASIC interpreter are listed as next steps.