PS1 BIOS for ArmSX1 — Which File You Need and How to Add It

ArmSX1 runs PlayStation 1 games on Android, but like the console itself it needs a BIOS — the PS1's system firmware — before any game will start. This page explains which BIOS files ArmSX1 recognises and how to add yours.

This site does not host or link to BIOS files. The PS1 BIOS is Sony's copyrighted code; the legal way to get one is to dump it from a PlayStation you own.

What the BIOS does

Every PlayStation has a 512 KB chip holding its BIOS. It shows the Sony boot logo, runs the memory card manager and CD player when no game is inserted, and provides system routines that games call while they run. ArmSX1 emulates the console's hardware, but it boots games through a real BIOS dump rather than reimplementing that firmware.

Which BIOS matches your games

PlayStation BIOS versions are tied to a console model and a region. Use one from the same region as your games — you can tell a game's region from its serial on the disc or the case.

Region Game serials start with Console models ArmSX1 recognises
North America (NTSC-U) SLUS, SCUS SCPH-1001, 5501, 5503, 7001, 7003, 7501, 9001, 101
Europe (PAL) SLES, SCES SCPH-1002, 5502, 5552, 7002, 7502, 9002, 102
Japan (NTSC-J) SLPS, SCPS SCPH-1000, 3000, 3500, 5000, 5500, 7000, 7500, 9000, 100

Later revisions are generally the better pick within a region. Adding one BIOS for each region you own games from lets ArmSX1 choose the right one automatically.

How ArmSX1 checks your file

  • The name does not matter. ArmSX1 identifies a BIOS by a checksum of its contents, so scph5501.bin, SCPH-5501.BIN and bios.bin are all the same to it if the data is identical.
  • It must be exactly 512 KB (524,288 bytes). Files of any other size are skipped.
  • It must be unmodified. A patched or region-hacked BIOS no longer matches any known console, so ArmSX1 does not recognise it.
  • OpenBIOS is recognised too. It is an open-source replacement, not Sony's code, and works for many games but not all of them.

How to add your BIOS

  1. Put your BIOS files in one folder.

    Extract them first if they are inside a ZIP. Memory card files (.mec, .nvm) can sit in the same folder; ArmSX1 picks them up too.

  2. Open ArmSX1 and go to BIOS Location.

    On a fresh install this is a step in the first-run setup. Tap Pick BIOS Folder and choose the folder from step 1.

  3. Select your BIOS.

    ArmSX1 scans the folder and lists every BIOS it recognises with its region. Choose one and tap Use Selected BIOS. If it reports No valid PS1 BIOS files found in that folder, check the size and that the file is unmodified.

  4. Change it later in BIOS settings.

    Preferred console model sets which BIOS ArmSX1 tries first at the next game start; if no matching dump is available, it selects one automatically. Import BIOS file… adds another dump, and a BIOS can be applied to This game only.

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Frequently Asked Questions

The BIOS is the PlayStation's own system firmware. It boots the console, shows the memory card and CD player screens, and provides routines that games call while they run. ArmSX1 boots games through a real BIOS dump, so without one there is nothing to start them with.

One that matches the region of your games: a North American model such as SCPH-1001, SCPH-5501 or SCPH-7001 for US games, a European model such as SCPH-1002, SCPH-5502 or SCPH-7502 for PAL games, and a Japanese model such as SCPH-1000, SCPH-5500 or SCPH-7000 for Japanese games. Adding all three regions lets ArmSX1 pick the right one per game.

No. ArmSX1 identifies a BIOS by a checksum of its contents, not by its name, so scph5501.bin and bios.bin are treated the same if the data is identical. The file must be exactly 512 KB; anything else is skipped.

The folder you picked has no file it recognises. Usually the dump is the wrong size, is compressed inside a ZIP, or is a modified or patched BIOS whose checksum matches no known console. Extract it and use an unmodified 512 KB dump.

Yes. The BIOS screen can apply a BIOS to the current game only, while every other game keeps using the global choice.

ArmSX1 recognises OpenBIOS, the open-source PS1 BIOS replacement, as a valid BIOS. It is not a dump of Sony's code, but it is also not a perfect substitute: some games that rely on exact BIOS behaviour may not run with it.

No. The PS1 BIOS is copyrighted Sony code, and this site does not host or link to copies of it. Dump it from a PlayStation you own.