Here's the currently available, though incomplete, list, with explanations,
of error codes generated by the Apple IIGS when running system diagnostics
for the Apple II Family (V1.0B1).
Apple IIGS error codes have the form AABBCCDD.
Test numbers AA
Error Code (AA) Test
--------------- ----------------------------
"RM"/01 Checksum
02 RAM Moving Inversions
03 Softswitch
04 RAM Address
05 FPI Speed
06 Serial I/O
07 Real Time Clock
08 Battery RAM
09 Front Desk Bus
0A Shadowing
0B Interrupts
AA=06 serial test
BB Meaning
-- -----------
01 Register R/W
04 Tx Buffer empty status
05 Tx Buffer empty failure
06 All sent status fail
07 Rx char available
08 Bad data
AA=03 RAM test
BBCC= Address
AA=01 ROM Checksum
BB= Failed checksum
DD=1 Bad RAM
AA=05 Speed
BB=1 speed stuck slow
BB=2 speed stuck fast
AA=08 Battery RAM
BB=01 address test failure and CC= bad address
BB=02 memory failure and CC = pattern, DD = Address
AA=02 Softswitches
Bb= Statereg bit
CC= Read softswitch address
AA=04 Front Desk Bus
BBCC= Bad checksum found
DD=01 FDB toolcode encountered a fatal error and no checksum computed
AA=04 Ram Adddress
BB= failed bank No
CC= failed bit
AA=06 Clock Test
BBCCDD=not used
DD=01 a fatal error occcurred after the test to within a second
AA=0A shadow register functionality
AA=0B Mega II and VGC capability of generating interrupts.
BB=01 VBL interrupt timeout
BB=02 VBL IRQ status fail
BB=03 1/4 SEC interrupt
BB=04 1/4 SEC interrupt
BB=05 ---
BB=06 VGC IRQ
BB=07 SCAN Line