System self-test

AES and MVS BIOSes compute their own checksums and compare them against the 16bit value at address $000080. The checksum is a simple byte sum of the whole ROM except locations $000080 and $000081.

=AES (all versions ?)=

Screen color meanings (information by Channelmaniac):
 * Blue: All tests passed (The AES does not test the Z80 sound IC).
 * Red: Work RAM error ($100000 region).
 * Green: Palette RAM error ($400000 region).
 * Yellow: Video RAM error (programmed through custom port).
 * Pink: BIOS checksum error (0xC00000 region).
 * Cyan: Memory card error (only tested if card in unit and blank).

=MVS (SP-E VERSION 0)=



Information by Channelmaniac:

When a MVS board is powered up without a cartridge installed, the border color around the edges of the crosshatch screen indicates the BIOS region:


 * Green: 6 slot, an older BIOS
 * Light blue: USA BIOS, labelled SPU2
 * Dark blue: Spanish BIOS, labelled SPS2
 * Red: Japanese BIOS, labelled SPJ2

Check order ?

Possible errors:
 * WORK RAM ERROR (68k RAM)
 * BACKUP RAM ERROR (Battery-backed RAM)
 * COLOR RAM BANK0 ERROR (First bank of 256 palettes)
 * COLOR RAM BANK1 ERROR (Second bank of 256 palettes)
 * VIDEO RAM ERROR (VRAM)
 * CALENDAR ERROR
 * SYSTEM ROM ERROR (BIOS ROM checksum fail)
 * MEMORY CARD ERROR
 * Z80 ERROR (no reply to sound command $01)