One Gamer’s Quest for the Smallest Original PS1 Resulted in This Palm-Sized PlayStation

Sony packed the first PlayStation into the small PSOne years ago, but even that version appeared too large for some die-hard fans. Secret Hobbyist is one of these gamers that went above and above. He chose to reconstruct the console’s core on a board tiny enough to fit in the palm of his hand, with no emulation and only authentic Sony components.

Secret Hobbyist began with a late PSOne model, which already had a simplified two-layer PCB, making the process slightly easier in contrast to previous models. He then disassembled it and examined every trace under a microscope. After cleaning the board, he was able to see the copper pathways clearly and proceeded to probe thousands of connections with a voltmeter to map the entire circuit. This was not a job for the impatient, as every wire and joint had to exactly match the original pattern, leaving no room for error.

Only when he had the schematic in place did he replicate it in KiCAD. This time, he chose a four-layer board, which provided him a lot more flexibility in routing the signals without interference and, most critically, allowed him to make it considerably smaller than the PSOne’s already reduced main board, significantly shrinking the console’s heart.

Secret Hobbyist made getting rid of the CD drive a top priority because it was simply too large. So he integrated a PSIO board, a device that ordinarily fits in a full-size PlayStation and allows it to load games from an SD card, but in the case of the PSOne, he had to fiddle with it to fit. As a bonus, he was able to remove one integrated circuit (the sub-CPU), transfer its operations to the new board, and everything went perfectly.

Original Sony parts were still utilized for the CPU, GPU, sound processor, and other critical components. One extra component (a digital to analog converter) was added to the crew to allow for VGA output, which was a great touch given how limited normal composite or S-Video is. The components were carefully laid out, with the CPU RAM nestled under the processor, the GPU and DAC on top, the BIOS next to the CPU, and the sound unit at the bottom. In the upper right corner, there is an oscillator circuit with some additional space for future projects.
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