In April I wrote a post on how to install a MM3 modchip into a PM-41 NTSC PSone console. This is a similar post, but covering anSCPH-7501 PlayStation 1 MM3 modchip installation. An MM3 modchip allows the PlayStation to boot directly to game backups burned to CDs.
MM3 modchips also allow you to run games from other regions. You can buy an MM3 chip for not a whole lot of money, they're around $4-10. Cost primarily depending on how long you want to wait for your chip. Buying a chip from China is cheaper, but takes longer to arrive. I purchased my chip from a US seller on eBay preprogrammed and prewired for $8 shipped.