AST introduced an enhanced
BIOS in 1992 with 3 beeps before all early POST failure messages.
Otherwise, the most sifnificant digit of the POST code indicates the number
of long beeps and the least significant digit indicates the short beeps.
After 20, this dosen't work.
| 00 |
Reserved; Beep and halt
if error occurs |
| 01 |
Test CPU registers |
| 02 |
Test the 8042 keyboard
controller buffer |
| 03 |
Test the 8042 keyboard
controller reset |
| 04 |
Verify presence of keyboard
and check communication |
| 05 |
Read keyboard input port
(WS386SX16) |
| 06 |
Initialize system board
support chipset |
| 09 |
Test BIOS ROM checksum |
| 0D |
Test 8254 programmable
interrupt timer registers (13 short beeps) |
| 0E |
Test ASIC registers (CLEM
only, 14 short beeps) |
| 0F |
Test CMOS RAM shutdown
byte (15 short beeps) |
| 10 |
Test DMA controller 0 registers |
| 11 |
Test DMA controller 1 registers |
| 12 |
Test DMA page registers
(EGA.VGA vertical retrace failed) |
| 13 |
EGA/VGA RAM test failed |
| 14 |
Test memory refresh toggle
(EGA/VGA CRT registers failed) |
| 15 |
Test base 64KB memory |
| 16 |
Set interrupt vectors in
base memory |
| 17 |
Initialize video |
| 18 |
Test display memory |
| 20 |
EISA bus board power on
(EISA systems only) |
| 30 |
Test programmable interrupt
controller #1 mask register |
| 31 |
Test programmable interrupt
controller #2 mask register |
| 32 |
Test programmable interrupt
controller's for stuck interrupts |
| 33 |
Test for stuck NMI (P386
25.33, P486, CLAM and EISA) |
| 34 |
Test for stuck DDNIL status
(CLEM only) |
| 40 |
Test CMOS RAM backup battery |
| 41 |
Calculate and verify CMOS
checksum |
| 42 |
Setup CMOS RAM options
(except WS386SX16) |
| 50 |
Test the protected mode |
| 51 |
Test protected mode exceptions |
| 60 |
Calculate RAM size |
| 61 |
Test RAM |
| 62 |
Test shadow RAM (WS386SX16,
P386 25/33, P486, CLEM, EISA); test cache (P386/16) |
| 63 |
Test cache memory (P386
25/33, P486, CLEM, EISA); copy video BIOS to shadow RAM (p386C, P386/16,
WS386SX16) |
| 64 |
Copy system BIOS to shadow
RAM (P386 25/33, P486, CLEM,EISA); Copy video BIOS to shadow RAM (P386
16, WS386SX16) |
| 65 |
Copy video BIOS to shadow
RAM P386 25/33, P486, CLEM,EISA); Test cache (WS386SX16) |
| 66 |
Test 8254 programmable
interrupt timer channel 2 (P386 25/33, P486, EISA) |
| 67 |
Initialize memory (Eagle
only) |