PSP Firmware 4.21 for Playing PC Games? Don't Upgrade—Stay Lower for Custom Firmware

Do NOT update to firmware 4.21 (or higher) if you want to play PSP games copied from PC. Custom Firmware (CFW) — required for homebrew, ISOs, CSOs, plugins — only installs on firmware 4.21 or lower. Sony patched the exploit in 4.22+.

Current Firmware Check

1. PSP → Settings → System Settings → System Information.
2. Read "System Software" version.
3. ≤ 4.21: Good. Proceed to CFW install.
4. > 4.21 (4.22–6.61): Cannot install permanent CFW. Only temporary HEN (Homebrew ENabler) via Infinity / h-encore (requires specific game exploit).

If ≤ 4.21: Install CFW (Permanent, Best)

1. Identify Model: Back sticker → PSP-1000 (Fat), PSP-2000 (Slim), PSP-3000 (Bright), PSP-N1000 (Go), PSP-E1000 (Street).
2. Check Motherboard (PSP-2000/3000 only): Battery compartment → TA-088v3 or TA-090v2 = unhackable (need Pandora + MMS). Others = hackable.
3. Download CFW Installer: PRO-C2 / ME-2.3 / LME-2.3 (for 6.60/6.61) or 6.60 PRO-C2 / 6.61 ME-2.3 for modern. For ≤4.21: 5.50 GEN-D3, 5.50 Prome-4, 6.20 PRO-B10, 6.35 PRO-B10, 6.39 PRO-B10, 6.60 PRO-C2.
4. Install: Copy to PSP/GAME/UPDATE/ → Run from Game → Memory Stick. Follow on-screen.
5. Result: Permanent CFW (survives reboot). Homebrew, ISOs, plugins, themes work.

If > 4.21: Temporary HEN (Infinity / h-encore)

• Requires specific exploit game (e.g., Patapon 2, Everybody's Tennis, MotorStorm Arctic Edge — varies by firmware).
• Install Infinity 2.3 (6.60/6.61) or h-encore (3.60–3.73 Vita, not PSP).
• HEN must be re-activated after every cold boot (Fast Recovery helps).
• Less stable than permanent CFW.

Playing PC Games on PSP (ISO/CSO)

1. Own the game legally (rip your UMD or buy digital).
2. Convert to .CSO (compressed ISO) using UMDGen (PC) — saves space.
3. Copy to ms0:/ISO/ (or ef0:/ISO/ for Go).
4. Launch from CFW Game menu.

Critical Warnings

• Backup NAND before CFW (use NAND Tool or PSP Filer). Bricks happen.
• Battery: Use AC adapter during flash. Power loss = brick.
• Region: CFW is region-agnostic. Games: match region or use region-free patch.
• Legal: Downloading ISOs you don't own = piracy. Ripping your own UMDs = legal backup (varies by country).

Stay on ≤4.21 for easy permanent CFW. If already higher: Infinity HEN or buy a hackable unit ($30–$50).