Raph Levien, November 7, 2026. The article introduces vic-2350, a re-envisioning of an 80s home computer built on an RP2350 microcontroller board. To achieve text rendering, the author chose bitmap fonts for efficiency and aesthetic preference at low resolutions, favoring crisp, intentionally designed fonts over antialiased rendering. The need for proportional spacing and kerning, inspired by early Macintosh predecessors, drove the development of a JIT technique for generating highly optimized code on the fly for rendering strings. Racing the beam is employed to fill the video buffer each scanline, a necessity given the RP2350's 520kB SRAM limit. The renderer, written in the custom symbolasm language, operates under a strict budget of approximately 6 cycles per pixel. A JIT speeds up this process, allowing more cycles for graphical objects and app functions. The display list is double-buffered, with one buffer scanned out while the application builds the other, swapping at each vsync if ready. Display objects are packed into two vectors: one for the objects themselves and another for indices.
The piece traces the history of text rendering from the fixed cell technique of the mid-80s to the flexible but power-hungry framebuffer approach. It explains the trade-offs between hardware lookup and software rendering, culminating in the JIT solution for the RP2350's constraints. The author emphasizes the balance between visual richness, latency, and the strict performance budget required for real-time video buffer filling.
Source: Hacker News · Summarized by HeadlinesBriefing