A Raspberry Pi Pico's RP2040 replaces a dead STN LCD in a 1990s Samsung cash register, no FPGA required. Voltage Ventures reverse-engineered the display's 4-bit parallel data bus, identified the timing signals, and used the microcontroller to transpose the output to monochrome VGA on a modern panel. The original display ran at 320x240 pixels, which made the signal analysis tractable enough to prototype first on an STM-series chip before moving to the RP2040.
The interesting part is the methodology, not just the result. Sampling a 4-bit bus from an undocumented 30-year-old cash register display and reconstructing its timing protocol without a datasheet is a replicable process. The full write-up on Instructables details exactly how they did it, which makes this useful for anyone staring down a dead proprietary display with no replacement in sight.
The broader point: display translation typically requires dedicated silicon or an FPGA. This project is a documented counterexample. If your target display is low-resolution and monochrome, a $4 microcontroller may be all you need.
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