System self-test

Todo: Order of checks.

Cartridge systems

Some information by Channelmaniac.

The AES home console only performs checks when no game is detected.

Error	No game	WORK RAM ERROR	COLOR RAM ERROR	VIDEO RAM ERROR	SYSTEM ROM ERROR	MEMORY CARD ERROR
AES
MVS	Crosshatch					Screenshot needed
Meaning	All tests passed (AES does not test the Z80). Cartridge not detected.	68k user RAM R/W error	Palette RAM R/W error	VRAM R/W error	System ROM checksum mismatch	Memory card R/W error (only tested if card present and blank)

MVS checks

Additionnal checks are performed on MVS systems. The SP-S2 system ROM does them in the following order:

1. Work RAM
2. Backup RAM
3. Palette RAM bank 0
4. Palette RAM bank 1
5. Low VRAM
6. High VRAM
7. RTC
8. System ROM checksum
9. Z80

Error	BACKUP RAM ERROR	Calendar freeze	CALENDAR ERROR	Z80 ERROR
Display
Meaning	Backup RAM R/W error	RTC isn't giving Time Pulse	RTC ran to slow or too fast	Z80 didn't reply to command

When a MVS board is powered up without cartridges inserted, the border color around the edges of the crosshatch screen indicates the system ROM region:

• Red: Japanese, SPJ2
• Cyan: USA, SPU2
• Blue: Korean/Spanish, SPS2
• Yellow: European
• Green: 6 slot (ROM name ?)

UniBios tests

The Universe BIOS does not use the above color codes to indicate errors.