| 00 |
Cold start |
| 01 |
Initialize KBD controller, Disable CPU cache, Initialize onboard I/O chipset, Test RAM size |
| 02 |
Disable critical I/O |
| 03 |
Checksum the BIOS ROM |
| 04 |
Test page register |
| 05 |
Enable A20 gate, issue 8042 keyboard controller self test |
| 06 |
Initialize ISA I/O |
| 07 |
Warm initialize KBD controller & I/O chipset |
| 08 |
Refresh toggle test |
| 09 |
Test DMA master & slave registers |
| 0A |
Test first 64KB of base memory |
| 0B |
Test master 8259 mask, test slave 8259 mask |
| 0C |
Test 8259 slave, initialize interrupt vectors 00-77h, initialize keyboard buffer variables |
| 0D |
Test timer 0, 8254 channel 0 |
| 0E |
Test 8254 channel 2, speaker channel |
| 10 |
Turn on monitor, show error messages |
| 11 |
Read and checksum the CMOS |
| 12 |
Call video ROM initialization routines |
| 13 |
Set 8Mhz AT-bus |
| 14 |
Size and test memory, stuck NMI check |
| 15 |
No keyboard and power on, retry keyboard initialization |
| 16 |
Size and test CPU cache |
| 17 |
Test A20 off and on gates |
| 18 |
External memory size, stuck NMI check |
| 19 |
System memory size, stuck NMI check |
| 1A |
Test RTC time |
| 1B |
Determine serial ports |
| 1C |
Determine parallel ports |
| 1D |
Initialize numeric coprocessor |
| 1E |
Determine floppy diskette drive controllers |
| 1F |
Determine IDE controllers |
| 20 |
Display CMOS configuration changes |
| 21 |
Clear screens |
| 22 |
Set/reset numlock LED, security functions |
| 23 |
Final onboard serial and parallel ports check |
| 24 |
Set keyboard typematic rate |
| 25 |
Initialize floppy controller |
| 26 |
Initialize ATA discs |
| 27 |
Set video mode for primary adapter` |
| 28 |
Cyrix WB-CPU support, purge 8259 slave |
| 29 |
Reset A20 to OFF, Install adapter ROM's |
| 2A |
Clear primary screen, convert RTC to system ticks, set final DOS timer variable |
| 2B |
Enable NMI and latch |
| 2E |
Fast A20, fix A20 |
| 2F |
Purge 8259 slave, control to interrupt 19 boot |
| 32 |
Test CPU burst |
| 34 |
Determine 8042, set warm boot flag STS 2 |
| 35 |
Test high memory area wrap, verify A20 via F000:10 high memory area |
| 37 |
CPU step NZ, CPUID, disable CPU features |
| 38 |
Set 8042 pins |
| 39 |
PCI bus |
| 3A |
Scan PCI bus |
| 3B |
Initialize PCI bus with intermediate defaults |
| 3C |
Initialize PCI OEM: OEM bridge |
| 3D |
PCI bus and Plug & Play: initialize AT slotman from AT bus CDE usage |
| 3E |
Find phantom CDE ROM PCI cards |
| 3F |
PCI bus: final fast back-to-back state |
| 40 |
OEM post initialization, hook audio |
| 41 |
Allocate I/O on PCI bus, logs in PCI-IDE |
| 42 |
Hook PCI-ATA chips |
| 43 |
Allocate IRQ's to PCI bus, enable ATA IRQ's |
| 44 |
Allocate and enable PCI memory/ROM space |
| 45 |
Determine PS/2 mouse |
| 46 |
Map IRQ's to PCI bus, enable ATA IRQ's |
| 47 |
PCI-ROM install, note user CMOS |
| 48 |
If setup conditions: execute setup utility |
| 49 |
Test F000, transfer EPROM to shadow RAM |
| 4A |
Hook VLATA chip |
| 4B |
Identify and spin up all drives |
| 4C |
Detect secondary IRQ, if VL/AT bus IDE exists but it's IRQ not known yet |
| 4D |
Detect /log 32-bit I/O ATA devices |
| 4E |
Atapi drive M/S bitmap to shadow RAM, set interrupt 13 vector |
| 4F |
Finalize shadow RAM |
| 50 |
Chain interrupt 13 |
| 51 |
Load Plug & Play, processor vector initialized, BIOS vector initialized, OEM vector initialized |
| 52 |
Scan for Plug & Play, update Plug & Play device count |
| 53 |
Supplement IRQ usage, AT IRQ's |
| 54 |
Conditionally assign everything Plug & Play wants |
| 58 |
OEM custom boot sequence just prior to interrupt 19 boot |
| 59 |
Pass control to interrupt 19 boot |
| 5A |
Display MR BIOS logo |
| 88 |
Dead motherboard and/or BIOS ROM |
| FF |
BIOS POST finished |