Code

Meaning

01

Test CPU registers

02

Test system I/0 port?awrite and read port 61 to confirm it will handle RAM refresh.

03

Test ROM BIOS checksum

04

Test DMA page registers

05

Test timer channel 1 (refresh)

06

Test timer channel 2 (speaker)

07

Test RAM refresh logic. Also verifies timer is working.

08

Test base 64K RAM

09

Test 8/16 bit bus conversion

0A

Test interrupt controller 1

0B

Test interrupt controller 2

0C

Test I/O controller

0D

Test CMOS RAM read/write

0E

Test for battery power low or interrupted since last test

0F

Test CMOS RAM checksum

10

Test CPU protected mode

11

Test video configuration in CMOS RAM or display switch

12

Test primary video controller

13

Test secondary video controller

20

Display results of tests to this point

21

Test DMA controller 1

22

Test DMA controller 2

23

Test Timer channel 0 (system timer tick)

24

Initialize interrupt controllers

25

Test interrupts

26

Test interrupts

30

Check base 640K memory size

31

Check extended memory size

32

Test higher 8 address lines

33

Test base memory

34

Test extended memory

40

Test keyboard?aenable/disable

41

Test keyboard?areset

42

Test keyboard?aclock low

43

Test keyboard?afor interrupt, enable keyboard, init pointers, write out subcommand

44

Test 8086 address overrun compatibility (gate A20)

50

Set up hardware interrupt vectors

51

Enable interrupt from timer channel 0

52

Security ROM

60

Test floppy disk controller and drive

61

Test hard disk controller

62

Initialize floppy drives

63

Initialize hard drives

70

Test real time clock

71

Set time of day in real time clock

72

Check parallel interfaces

73

Check serial interfaces

74

Check for and execute adapter option ROMs

75

Check if math coprocessor is installed and enable interrupt

76

Enable keyboard and real time clock interrupts

F0

System not configured correctly, or hardware defect

F1

Scan for and execute motherboard option ROMs

F2

INT 19 to boot operating system?aNo POST errors.