JIT bitmap text rendering for microcontrollers

Raph Levien has developed a just-in-time (JIT) compilation technique for rendering proportional bitmap text on RP2350 microcontrollers, achieving roughly 6 cycles per pixel within the tight scanline budget of his race-the-beam renderer for the vic-2350 retro computer project. The approach generates optimized rendering code on the fly for each string, departing from the fixed character cell method most RP2350 projects use and enabling proportional spacing and kerning despite the chip's limited 520kB of SRAM. Levien chose bitmap fonts over antialiased rendering for efficiency and aesthetics at low resolution, drawing on the early Macintosh tradition. The work matters because software must fill the HSTX DVI video buffer entirely on the RP2350, making rendering speed a hard constraint, and Levien notes Rust alone could not meet the performance requirements. Watch for whether the JIT technique is adopted by other RP2350 projects and extended beyond the race-the-beam renderer to framebuffer-based implementations.