POST function codes

This is the list of POST function codes of the PS/1 model 2011. They are emitted on I/O ports 190h and 3BCh (the parallel port).

01 = CPU flag and register tested
02 = BIOS ROM 8bit checksum
03 = POS registers checked
04 = ports 205h, 322h, CMOS reg 0F
05 = PIT tested
06 = DMA Controllers 1 and 2 tested with pattern FF0055AA
07 = DMA page registers tested
08 = Initialise DMA command & mode registers
09 = KB controller test refresh (port 61)
0A = Test keyboard controller buffers
0B = KB controller self test
0C = KB controller self test completed
0D = KB controller configuration error
0E = POST reset flag
0F = Test first 64K RAM in real mode
10 = Memory error in the first 64KB
11 = IDT, GDT, DF test
12 = PIC init
14 = Initialise default IVT
15 = Set BIOS data area
16 = RTC battery check
17 = Init LPT; check CMOS checksum; set CMOS defaults
18 = RTC/CMOS lost power
19 = RAM enable
1A = Enable Protected Mode
1B = Protected Mode test
1C = Decide low memory size in protected mode; Size base memory
1D = Save memory size detected
1E = Check for extended memory beyond 1mb
1F = Save detected extended memory size
20 = Test memory address bus lines
21 = Clear parity error and channel check
23 = Determine CMOS validity
25 = Check for manufactoring test mode
3E = Virtual mode test completed, determine result, reset to real mode
3F = Virtual mode test successful
40 = Video initialization
41 = Video line feed
42 = Test PIC #1 & PIC #2 registers; Master/Slave test
43 = Test PIC #1 & PIC #2 registers with another pattern
44 = Check for interrupt
45 = Test NMI
46 = NMI error detected
47 = Test timer 2
48 = Check stuck speaker clock; speaker bitstuck test
49 = Test timer 0 count
4A = Test timer 2 output
4B = Check if timer interrupt occurred
4C = Test timer 0 for count too fast or slow
4D = Timer 0 reset
4E = Check 8042 ready for command; buffer free
4F = Check for soft reset
50 = Prepare for shutdown/protected mode
51 = Start protected mode memory test
52 = Test memory in 64K increments
53 = Check if memory test done
54 = Shutdown system and return to real mode
55 = Test for manufacture or regular test
56 = Disable keyboard and self-test (BAT)
57 = Check for keyboard self-test
58 = Keyboard self-test passed
59 = Test keyboard interface
5A = Initialise mouse
5B = Disable mouse
5C = Initialise interrupt vectors (8h-0Fh)
5D = Initialise interrupt vectors (70h-77h)
5E = Initialise interrupt vectors (2h,5h,18h,1Eh, 60h-6Fh)
5F = HDD select
60 = Set diskette rate
61 = Enable floppy IRQ
63 = Parallel port test
64 = Serial port test, KB/LPT/COM BIOS data area setup
65 = Various error condition test and RTC check
66 = Configure floppy drives
67 = Configure hard drive
68 = Enable system CPU arbitration
69 = Scan for optional ROMs, floppy configuration check
6A = LPT and COM address determination
6B = Equipment byte setup
6C = Test audio card & joystick option
6D = Set keyboard typematic rate; evaluate POST result (ok beep)
6E = Reset page register
6F = Prepare to boot
DD = Boot ROM DOS
70 = Determine boot device
71 = Read boot sector from floppy drive
72 = Read boot sector from HDD
B0 = SYSTEM ROM check
BE = Enable Protected mode
BF = Protected mode enabled