AT&T VER 3.0 BIOS POST Codes
- 01 - CPU test 1: verify CPU status bits
- 02 - Power-up check - Initialize motherboard and chipset with default values; Check 8042 keyboard controller buffer
- 03 - Clear 8042 keyboard controller - send command AA, fail if status is not 2 output buffer full
- 04 - Reset 8042 keyboard controller
- 05 - Get8042 keyboard controller manufacturing status
- 06 - Initialize motherboard chipset; disable color/mono video; disable 8237 DMA controller; reset 80x87 coprocessor; initialize 8255 timer 1; clear DMA/page registers/CMOS RAM shutdown byte
- 07 - CPU test 2; read/write/verify CPU registers SS, SP, BP, with FF and 00
- 08 - Initialize CMOS RAM/RTC
- 09 - Checksum 32K of BIOS ROM
- 0A - Initialize video interface; initialize 6845 controller
- 0B - Test 8254 programmable interrupt timer channel 0
- 0C - Test 8254 programmable interrupt timer channel 1
- 0D - Test 8254 programmable interrupt timer channel 2
- 0E - Test CMOS RAM shutdown byte
- 0F - Test extended CMOS RAM, if present
- 10 - Test 8237 DMA controller channel 0
- 11 - Test 8237 DMA controller channel 1
- 12 - Test 8237 DMA controller page registers
- 13 - Test 8741 keyboard controller interface
- 14 - Test memory refresh toggle
- 15 - Test first 64K of base memory
- 16 - Set up interrupt tables in low memory
- 17 - Set up video I/O operations
- 18 - Test MDA/CGA video memory unless EGA/VGA adapter is found
- 19 - Test 8259 programmable interrupt timer channel 1
- 1A - Test 8259 programmable interrupt timer channel 0
- 1B - Test CMOS RAM battery level
- 1C - Test CMOS RAM checksum
- 1D - Set system memory size parameters
- 1E - Size base memory 64K at a time
- 1F - Test base memory found from 64K to 640K
- 20 - Test stuck bit in 8259 programmable interrupt controller
- 21 - Test for stuck NMI bits
- 22 - Test 8259 programmable interrupt controller functionality
- 23 - Test protected mode
- 24 - Size extended memory above 1MB
- 25 - Test all base and extended memory found, except the first 64K
- 26 - Test protected mode exceptions
- 27 - Initialize shadow RAM and move system BIOS and/or video BIOS into it if enabled by CMOS RAM setup
- 28 - Detect and initialize Intel 8242/8248 chip
- 2A - Detect and initialize keyboard
- 2B - Detect and initialize floppy drive
- 2C - Detect and initialize serial ports
- 2D - Detect and initialize parallel ports
- 2E - Detect and initialize hard drive
- 2F - Detect and initialize coprocessor
- 31 - Detect and initialize adapter ROM's
- BD - Initialize Orvonton cache controller, if present
- CA - Initialize 386 Micronics cache, if present
- CC - Shutdown NMI handler
- EE - Test for unexpected processor exception
- FF - Interrupt 19 boot loader