Keeping a PC from the early 2000s or even late 1990s working is a difficult job. Leaking capacitors and clock batteries are the least of your worries. Most likely the retro PC has an aging hard drive with a Parallel ATA interface that is no longer as reliable as it were in the day. A logical course of action will be to replace it with an SSD. While there are cheap PATA SSDs on the market, they will one day become extinct, making it difficult to fix those old PCs. Apparently, there is a solution: build your own 2.5-inch SSD with an IDE interface.
This is perhaps what Dosdude1 thought as he decided to build their own drive based on Silicon Motion's SM2236 controller and up to four 512Gb NAND ICs in a BGA152 or BGA132 packaging. Ironically, to build an SSD (whether one of the best SSDs or a cheap drive), one needs basic PCB routing, soldering, and programming skills. Meanwhile, to produce NAND flash memory and an SSD controller, one needs multi-billion fabs and advanced packaging facilities.
The GitHub post created by Dosdude1 contains blueprints of a 2.5-inch PATA SSD powered by the SMI SM2236 controller, a PCB design, and PCB schematics. The information gleaned from open documents and a serious amount of reverse engineering. Those who decide to build such an SSD will have to procure the controller, memory chips, and build a printed circuit board using the provided design. Also, they will have to find Silicon Motion's SM2236 Mass Production Tool (MPTool) that lists compatible memory chips as well as datasheets for those NAND ICs to set correct voltages for these chips.