"The computer book of the month is The Bios Companion
by Phil Croucher. Long-time readers of this column will recall I
have recommended his book before. This tells you everything you
ought to know about the BIOS in your system. Post codes, options,
upgrades, you name it.

Years ago, I called an earlier edition
of this invaluable and I see no reason to change my view.
Recommended."

Jerry Pournelle
Byte Magazine

"Croucher's book was invaluable 20 years ago and remains so
today...... Every one of the 468 pages holds useful information, the
author having zero tolerance for padding."

Davey
Winder
PC Plus Magazine

"You've completerly impressed me with the quality and scope of
your guides - extreme care has obviously gone into their research
and preparation."

Jeremy Fleming

"His style is lovely: clear, jargon-free where possible,
chatty and friendly with beautiful short paragraphs. It
[Communications & Networks] joins my list of 'I wish I'd written
it' books. I haven't come across such a good subject book in a long
time at this price."

Lorna Kyle
Personal Computer World

"To any micro owner who wants to know what this comms business
is all about, [Communications & Networks] is certainly one of
the best around. ... Croucher is not only knowledgable about his
subject, he's interested in it and communicates that interest to
you. "

Ron Peck
New Computer Express

"There are few books about which explain as accurately and
comprehensively as [Communications & Networks] does what
communications are all about. The glossary is
excellent."

Micro Decision

"...any PC user with a genuine interest in using his machine
to its full potential will recognise [Communications & Networks]
for the completely invaluable tool and often the inspiration that it
is."

Yvonne Taylor
Which PC

"[Communications & Networks] is the type of book you can
read on a bus or train without getting a headache from trying to
understand what it means."

Network

"As a recently reformed computer illiterate myself, I
appreciated the author's straighforward yet humourous and
light-hearted style of writing. He manages to strike the balance
between too much and too little information. ... [Computing Under
Protest] is never in danger of either boring or confusing the
reader."

Emma Tyrrall
Practical PC

"Good documentation is important for any software, but even
more so for an operating system - the documentation [for DOS 386
Professional] has some exceptionally clear explanations. Altogether,
the documentation is an example of the right way of doing things,
and other software manufacturers would do well to take
note."

Matthew Holbrook
Computer Shopper

"The DOS 386 Professional manual sets arrived at 2130 local
time today. We have had a brief look at them and wish to
congratulate IMS on the excellent, clear and concise manner in which
they have been presented."

Fred Parker
ETL Soft

"I remain impressed by Mr. Croucher's fluid writing style,
practical orientation, enthusiasm, and strong technical
knowledge."

Lance A Leventhal
Slawson Communications, Inc

JAR Professional Pilot Studies

"Its real value lies in taking the plethora of booklets and
ring-bound photocopies associated with commercial examinations and
condensing them into an attractive and portable form. The guy really
does deserve a medal ~ he has made a genuine contribution to the
body of professional aviation literature assembled during the course
of the last century.

I heartily recommend it to students of commercial flight, if only
as a souvenir of their efforts... "

Colin Hilton
Pro Pilot's Rumour Network

"(The) Book is quite a good compliment to our notes for
students. We will be recommending all our students buy the books....
"

Chris
Naples Air Centre

"I got your book last month and am in the process of ploughing
through it! Actually, I really like it and find it very interesting
and easy to read."

Simon Rouse

"So far I have found your book an extremely helpful reference
manual to carry around in my flight bag."

Blair Clubley

"I wish to commend you on a "work of art". I wish the CAA
would produce a quick reference easy to read manual such as yours.
Truly wonderful!"

Ebrahim Parkar

Post Codes

Acer
ALR
AMI
Arche
AST
AT&T

Award
Chips
& Technologies
Compaq
Dell
DTK
Eurosoft/Mylex

Faraday
A-Tease
HP
IBM
Intel
Landmark
Microid/MR
NCR

Olivetti
Philips
Phoenix
Quadtel
Supersoft
Tandon
Zenith

HP POST Codes

Derived from Phoenix, all POST information is sent to
the screen.

Note: Not all POST codes are included below -
the latest information is in the The BIOS
Companion, which contains over 100 pages of them.

POST
Procedures

Vectra

Vectra
ES

Vectra
QS & RS

Pavilion
3100 & 8000

POST
Procedures

CPU

Registers in CPU tested with data patterns, error
flags are set, verified and reset

ROM BIOS Checksum

Checksums are performed on high and low BIOS
chips

PIC Test

Test timer channels 0-2 then the memory refresh
signal.  Initialize timer if tests are passed.
Check the 8254 chip

64K Test

Walking bit and address collision tests are
performed on the first 64K of memory.  Check for a bad
memory chip or address line

Cache Controller

The the CPU cache controller and
memory

Video Adapter

Initialize the video adapter.  If EGA.VGA is
present, wait for the adapter to finish internal
diagnostics.  Check for adapter or improper setup if a
failure occurs

DMA Test

Bit patterns written to all DMA controller
registers, including page registers, and verifies the patterns
written.   If the tests pass the registers are reset and
the controller initialized

PIC Test

Test mask register of master and slave interrupt
controllers.  Generate interrupt and monitor CPU to test
success.   Failure is normally down to the PIC but the
interrupt test uses the BIOS clock (interrupt) and the RTC, so
check those also

Keyboard Controller

Perform several tests on the 8042 keyboard
controller then send a series of interrupt request commands
via the 8259 PIC

HP-HIL Test

Test the HP-HIL (Hardware Interrupt Level)
controller with data patterns and verify it

CMOS Test

Perform a checksum on the standard and extended
CMOS RAM area.  Perform a register test and check byte
0D  to determine power status.  Check the CMOS
extended CMOS RAM or battery respectively if a failure
occurs

Manufacturing Loop

Search for diagnostic tool used in manufacturing
and run predetermined tests if found.  Otherwise continue
POST

Base Memory Test

Test RAM between 64K and 640K with several pattern
test.  The bit failure and bank can be determined by the
displayed hex code

Extended Memory Test

Test extended memory found.  Bank and failing
bit displayed by the hex code

RTC Test

Test the RTC portion of the CMOS chip

Keyboard Controller

Test keyboard controller.   Initialize
keyboard if no errors found

Floppy Disk

Test and initialize floppy controllers and drives
found.  Check specific errors with the displayed hex
code.  Check for correct setup or defective CMOS chip or
defective battery

Math Coprocessor

Test NPU registers and interrupt request
functions

CPU Clock Test

Test interface between CPU and system at different
speeds.  Check for incorrect clock setting for system
peripherals or a bad CPU or clock generator chip

Serial and Parallel Test

Test and initialize serial and parallel
ports.  Failure here will not halt the POST.  The
Vectra RS BIOS does not test the parallel port

Boot

Initialize the BIOS vector table, standard and
extended CMOS data areas and any adapter ROM's present.
Then call Int 19 boot loader and give control to it.
Failures past this point usually point to the hard drive or
corrupt bootloader code

Back to Top

Vectra

A failure during POST will emit four beeps, and a 4-digit hex
code to the monitor. Failures that occur before EGA/VGA monitors are
initialised will not be displayed, so use a mono instead. BIOSes
prior to March 1989 initialised the video before getting on with the
POST.

01

LED test

02

Processor test

03

System (BIOS) ROM test

04

RAM refresh timer test

05

Interrupt RAM test

06

Shadow the system ROM BIOS

07

CMOS RAM test

08

Internal cache memory test

09

Initialize the video card

10

Test external cache

11

Shadow option ROM's

12

Memory subsystem test

13

Initialize EISA/ISA hardware

14

8042 keyboard controller self test

15

Timer 0 / Timer 2 test

16

DMA subsystem test

17

Interrupt controller test

18

RAM address line independence test

19

Size extended memory

20

Real mode memory test (first 640K)

21

Shadow RAM test

22

Protected mode RAM test (extended RAM)

23

Real time clock test

24

Keyboard test

25

Mouse test

26

Hard disk test

27

LAN test

28

Flexible disk controller subsystem
test

29

Internal numeric coprocessor test

30

Weitek coprocessor test

31

Clock speed switching test

32

Serial port test

33

Parallel port test

Back to Top

Vectra
ES

000F

80286 CPU is bad

0010

Bad checksum on ROM 0

0011

Bad checksum on ROM 1

011X

One of the RTC registers is bad; Register =
x(0-D)

0120

RTC failed to tick

0240

CMOS/RTC has lost power

0241

Invalid checksum, IBM CMOS area

0280

Invalid checksum, HP CMOS area

02XY

One of the CMOS registers is bad; Register = XY -
40

0301

8042 failed to accept the reset
command

0302

8042 failed to respond to the reset
command

0303

8042 failed to reset

0311

8042 failed to accept the "WRITE CMD BYTE"
command

0312

8042 failed to accept the data of the above
command

0321

8042 failed to accept scancode from port
68

0322

8042 failed to respond to the above
scancode

0323

8042 responded incorrectly to the above
scancode

0331

8042 failed to accept command from port
6A

0332

8042 failed to generate SVC on port 67

0333

8042 generated HPINT type on port 65

0334

8042 failed the R/W register on port
69

0335

8042 failed to generate HPINT on IRQ
15

0336

8042 failed to generate HPINT on IRQ
12

0337

8042 failed to generate HPINT on IRQ
11

0338

8042 failed to generate HPINT on IRQ
10

0339

8042 failed to generate HPINT on IRQ 7

033A

8042 failed to generate HPINT on IRQ 5

033B

8042 failed to generate HPINT on IRQ 4

033C

8042 failed to generate HPINT on IRQ 3

0341

8042 failed keyboard interface test
command

0342

8042didn't respond to interface
command

0343

Keyboard clock line stuck low

0344

Keyboard clock line stuck high

0345

Keyboard data line stuck low

0346

Keyboard data line stuck high

0350

No ACK from keyboard self test command

0351

Bad ACK from keyboard self test
command

0352

Keyboard is dead or not connected

0353

No result from keyboard self test
command

0354

Keyboard self test failed

0401

8042 failed to enable gate A-20

0503

Serial port dead or non existent

0505

Serial port fails port register tests

0543

Parallel port dead or non-existent

06XX

Stuck key; XX=scancode of key

0700

Failed to switch to slow mode

0701

Failed to switch to dynamic mode

0702

Timer (channel 0) failed to interrupt

0703

Memory cycles too slow in slow mode

0704

Memory cycles too fast in slow mode

0705

I/O cycles too slow in slow mode

0706

I/O cycles too fast in slow mode

0707

Memory cycles too slow in dynamic mode

0708

Memory cycles too fast in dynamic mode

0709

I/O cycles too slow in dynamic mode

070A

I/O cycles too fast in dynamic mode

110X

One of the timer channels failed to register test /
X(0-2)=channel that failed

1200

Memory refresh signal stuck high

1201

Memory refresh signal stuck low

211X

DMA 1 failed R/W test at register x
(0-7)

212X

DMA 2 failed R/W test at register x
(0-7)

221X

Bad DMA page register; X=register 0-7

300X

HP-HIL controller failed self test;
X=data

X = xx1 = >read/write fail with data =
0DA5h

X = xx1x = >read/write fail with data =
0DA5h

X = x1xx = >read/write fail with data =
0DA5h

X = 1xxx = >read/write fail with data =
0DA5h

3010

HP-HIL device test failed

4XYZ

Lower 640K failed R/W test;

X=0,2,4,6   Y>0=Bad U23
Z>0=Bad U13

X=1,3,5,7   Y>0=Bad U43
Z>0=Bad U33

X=8
Y>0=Bad
U22     Z>0=Bad U12

X=9
Y>0=Bad
U42     Z>0=Bad U32

5XYZ

Lower 640K failed marching ones test

X = bbbx = > bbb (0-7) is # of 128K
bank

bbb0 = > Indicate even byte bad

bbb1 = > Indicate odd byte bad

YZ = bbbb bbbb = > Bits for which b = 1 are
bad

61XY

RAM address line XY stuck

Some address lines to RAM are stuck to 0 or
1

XY = 00bb bbbb = > RAM address line bbbbbb is
stuck

XY = 01bb bbbb = > Multiple address lines are
stuck (bbbbbb is the first bad one)

620X

Lower 640K parity error; Bank X

X = Address in 64K bank where parity error
occurred

if X = 0 to y, U21 and/or U31 is/are
bad

if X = 8 to 9, U11 and/ore U41 is/are
bad

63XY

Parity error above 1MB; Bank XY

Parity error has occurred during RAM test above the
first MB

XY = Address in 64K bank where parity
occurred

6400

Parity generator failed to detect
error

71XY

Master 8259 failed R/W; bits XY

XY = bbbb bbbb + > bits in which b = 1 is
bad

72XY

Slave 8259 failed R/W; bits XY

XY = bbbb bbbb = > bits in which b = 1 is
bad

7400

Master 8259 failed interrupt

7500

Slave 8259 failed interrupt

9XYZ

Floppy drive controller error

X=drive #

Y=0=1st level error

Z=0   Unsuccessful input
from FD

Z=1   Unsuccessful output
to FDC

Z=2  Error while executing
seek

Z=3  Error during
recalibrate

Z=4  Error verifying RAM
buffer

Z=5  Error while resetting
FDC

Z=6  Wrong drive
identified

Z=7  Wrong media
identified

Z=8  No interrupt from
FDC

Z=9  Failed to detect track
0

Z=A  Failed to detect index
pulse

Y>1=Higher level error

Y=1=Read sector error, side 0

Y=2=Read sector error, side 1

Y=3=Write sector error, side 0

Y=4=Write sector error, side 1

Y=5=Format sector error, side 0

Y=6=Format sector error, side 1

Y=7=Read ID error, side 0

Y=8=Read ID error, side 1

Z=1=No ID address
mark

Z=2=No data address
mark

Z=3=Media is write
protected

Z=4=Sector # wrong

Z=5=Cylinder #
wrong

Z=6=Bad cylinder

Z=7=DMA overrun

Z=8=ID CRC error

Z=9=Data CRC error

Z=A=End of cylinder

Z=B=Unrecognizable
error

A001

No 80287 detected

A002

80287 failed stack register R/W test

A00C

No zero-divide interrupt from 80287

CXYZ

R/W error on extended RAM in XY bank

Read/Write test failure on extended
RAM

X = 0 = > Even byte is bad

X = 1 = > Odd byte is bad

XY = Address in 64K bank where RAM failed

CFFF

Extended RAM marching ones failed

Marching on test failure on extended
RAM

X = 0 = > Even byte bad

X = 1 = > Odd byte bad

XA = Address in 64K bank where RAM
failed

Back to Top

Vectra QS
& RS

000F

386 CPU bad

0010

Bad checksum on ROM 0

0011

Bad checksum on ROM 1

011X

RTC register is bad

0120

RTC failed to tick

0240

CMOS/RTC lost power

0241

Invalid checksum, IBM CMOS area

0280

Invalid checksum, HP CMOS area

02XY

Bad CMOS register, at XY-40

0301

8042 failed to accept reset command

0302

8042 failed to respond to reset

0303

8042 failed on reset

0311

8042 didn't accept "WRITE CMD BYTE"

0312

8042 didn't accept data

0321

8042 failed to accept scancode, port
68

0322

8042 failed to respond to the above
scancode

0323

8042 responded incorrectly to the above
scancode

0331

8042 failed to accept command from port
6A

0332

8042 failed to generate SVC on port 67

0333

8042 generated HPINT type on port 65

0334

8042 failed the R/W register on port
69

0335

8042 failed to generate HPINT on IRQ
15

0336

8042 failed to generate HPINT on IRQ
12

0337

8042 failed to generate HPINT on IRQ
11

0338

8042 failed to generate HPINT on IRQ
10

0339

8042 failed to generate HPINT on IRQ 7

033A

8042 failed to generate HPINT on IRQ 5

033B

8042 failed to generate HPINT on IRQ 4

033C

8042 failed to generate HPINT on IRQ 3

0341

8042 failed keyboard interface test
command

0342

8042didn't respond to interface
command

0343

Keyboard clock line stuck low

0344

Keyboard clock line stuck high

0345

Keyboard data line stuck low

0346

Keyboard data line stuck high

0350

No ACK from keyboard self test command

0351

Bad ACK from keyboard self test
command

0352

Keyboard is dead or not connected

0353

No result from keyboard self test
command

0354

Keyboard self test failed

0401

8042 failed to enable gate A-20

0503

Serial port dead or non-existent

0505

Serial port fails port register tests

06XX

Stuck key; XX=scancode of key

0700

Failed to switch to slow speed

0701

Failed to switch to fast speed

0702

Timer failed to interrupt

0703

CPU clock too slow in slow speed

0704

CPU clock too fast in slow speed

0707

CPU clock too slow in fast speed

0708

CPU clock too fast in fast speed

0709

Failed to switch bus clock to ATCLK

110X

Timer X (0-2) failed to register test

1200

Memory refresh signal stuck high

1201

Memory refresh signal stuck low

211X

DMA 1 failed R/W test at register x
(0-7)

212X

DMA 2 failed R/W test at register x
(0-7)

221X

Bad DMA page register; X=register 0-7

300X

HP-HIL controller failed self test;
X=data

X = xxx1 = > read/write fail with data =
0DA5Ah

X = xx1x = > read/write fail with data =
0DA5Ah

X = x1xx = > read/write fail with data =
0DA5Ah

X = 1xxx = > read/write fail with data =
0DA5Ah

3010

HP-HIL device test failed

4XYZ

Lower 640K failed R/W test;

X=0,2,4,6   Y>0=Bad U23
Z>0=Bad U13

X=1,3,5,7   Y>0=Bad U43
Z>0=Bad U33

X=8
Y>0=Bad
U22     Z>0=Bad U12

X=9
Y>0=Bad
U42     Z>0=Bad U32

5XYZ

Lower 640K failed marching ones test

RAM in lower 640K failed read/write
test

X = bbcc = > bb is # 64K of 32 bit word
bank

cc = 00 = > byte 0 is bad

cc = 01 = > byte 1 is bad

cc = 02 = > byte 2 is bad

cc = 03 = > byte 3 is bad

YZ = bbbb bbbb = > bits for which b = 1 are
bad

61XY

RAM address line XY stuck

Some address lines to RAM are stuck to 0 or
1

XY = 00bb bbbb = > RAM address line bbbbbb is
stuck

XY = 01bb bbbb = > Multiple address lines are
stuck bbbbbb is the first bad one

620X

Lower 640K parity error; Bank X

X = Address in 64K bank where parity
occurred

63XY

Parity error above 1MB; Bank XY

XY = Address in 64K bank where parity
occurred

6500

Shadow RAM bad at BIOS segment

6510

Shadow RAM bad at HP EGA segment

71XY

Master 8259 failed R/W; bits XY

XY = bbbb bbbb = > bits which b = 1 is
bad

72XY

Slave 8259 failed R/W; bits XY

XY = bbbb bbbb = > bits which b = 1 is
bad

7400

Master 8259 failed interrupt

7500

Slave 8259 failed interrupt

9XYZ

Floppy drive controller error

X=drive #

Y=0=1st level error

Z=0   Unsuccessful input
from FD

Z=1   Unsuccessful output
to FDC

Z=2  Error while executing
seek

Z=3  Error during
recalibrate

Z=4  Error verifying RAM
buffer

Z=5  Error while resetting
FDC

Z=6  Wrong drive
identified

Z=7  Wrong media
identified

Z=8  No interrupt from
FDC

Z=9  Failed to detect track
0

Z=A  Failed to detect index
pulse

Y>1=Higher level error

Y=1=Read sector error, side 0

Y=2=Read sector error, side 1

Y=3=Write sector error, side 0

Y=4=Write sector error, side 1

Y=5=Format sector error, side 0

Y=6=Format sector error, side 1

Y=7=Read ID error, side 0

Y=8=Read ID error, side 1

Z=1=No ID address
mark

Z=2=No data address
mark

Z=3=Media is write
protected

Z=4=Sector # wrong

Z=5=Cylinder #
wrong

Z=6=Bad cylinder

Z=7=DMA overrun

Z=8=ID CRC error

Z=9=Data CRC error

Z=A=End of cylinder

Z=B=Unrecognizable
error

A001

No 80287 detected

A002

80287 failed stack register R/W test

A00C

No zero-divide interrupt from 80287

AF00

Weitek coprocessor didn't enter protected
mode

AF01

Weitek coprocessor nor present

AF02

Weitek coprocessor fails register test

AF05

Weitek coprocessor fails addition test

AF06

Weitek coprocessor fails interrupt
test

AF0C

Weitek coprocessor fails interrupt
test

CXYZ

R/W error on extended RAM in XY bank

X = 0 = > Even byte bad

X = 1 = > Odd byte bad

XY = Address in 64K bank where RAM
failed

CFFF

No extended RAM found

EXYZ

Extended RAM marching ones failure at
XYZ

X = 0 = > Byte 0 is bad

X = 1 = > Byte 1 is bad

X = 2 = > Byte 2 is bad

X = 3 = > Byte 3 is
bad

Back to Top

Pavilion 3100
& 8000

02

Verify real mode

03

Disable NMI

04

Get processor type

06

Initialize system hardware

08

Initialize chipset with POST values

09

Set IN-POST flags

0A

Initialize CPU registers

0B

Enable CPU registers

0C

Initialize cache to POST values

0E

Initialize I/O component

0F

Initialize local IDE bus

10

Initialize power management

11

Load alternate registers

12

Restore CPU control word during warm
boot

13

Initialize PCI bus mastering devices

14

Initialize keyboard controller

16

BIOS ROM checksum

17

Initialize cache before memory size

18

Initialize 8254 timer

1A

Initialize DMA controller

1C

Reset PIC

20

Test DRAM refresh

22

Test 8742 keyboard controller

24

Set ES segment register to 4GB

26

Enable A-20 line

28

Autosize DRAM

29

Initialize POST memory manager

2A

Clear 512K base RAM

2C

RAM address line failure

2E

RAM data failure, low byte

2F

Enable cache before BIOS shadow

30

RAM data failure, high byte

32

Test CPU, BUS clock frequency

33

Initialize POST dispatch manager

34

Test CMOS RAM

35

Initialize alternate chipset registers

36

Warm start shut-down

37

Reinitialize chipset (MB only)

38

Shadow system BIOS ROM

39

Reinitialize cache (MB only)

3A

Autosize cache

3C

Configure advanced chipset registers

3D

Load alternate registers new CMOS
values

40

Set initial CPU speed

42

Initialize interrupts

44

Initialize BIOS interrupts

45

POST device initialization

46

Check ROM copyright notice

47

Initialize manager for PCI option
ROM's

48

Check video config against CMOS

49

Initialize manager for PCI option
ROM's

4A

Initialize all video adapters

4B

Display quiet boot screen

4C

Shadow video BIOS

4E

Display BIOS copyright notice

50

Display CPU type & speed

51

Initialize

52

Test keyboard

54

Set key click if enabled

56

Enable keyboard

58

Test for unexpected interrupts

59

Initialize POST display service

5A

Display "Press F2 to Enter Setup"

5B

Disable CPU cache

5C

Test RAM, 512-640K

60

Test extended memory

62

Test extended memory address lines

64

Jump to user patch 1

66

Configure advanced cache registers

67

Initialize multi-processor APIC

68

Enable external & processor caches

69

Set up SMM area

6A

Display external L2 cache size

6C

Display shadow area message

6E

Display high address for UMB recovery

70

Display error message

72

Check for configuration errors

74

Test real time clock

76

Check for keyboard errors

7A

Test for key lock on

7C

Set up hardware interrupt vectors

7E

Initialize coprocessor, if present

80

Disable onboard super I/O ports

81

Late POST device initialization

82

Detect & install external RS-232
ports

83

Configure non-MDC IDE controllers

84

Detect & install external parallel
ports

85

Initialize PnP ISA devices

86

Reinitialize onboard I/O ports

87

Configure motherboard configurable
devices

88

Initialize BIOS data area

89

Enable NMI's

8A

Initialize extended BIOS data area

8B

Test & initialize PS/2 mouse

8C

Initialize floppy controller

8F

Determine number of ATA drives

90

Initialize hard disk controllers

91

Initialize local BUS HD controllers

92

Jump to user patch 2

93

Build MPTABLE for multiprocessor
boards

94

Disable A-20 line

95

Install CD-ROM for boot

96

Clear huge ES segment register

97

Fix up multiprocessor table

98

Search for options ROM's

99

Check for smart drive

9A

Shadow ROM option

9C

Set up power management

9E

Enable hardware interrupts

9F

Determine number of ATA & SCSI
drives

A0

Set time of day

A2

Check key lock

A4

Initialize typematic rate

A8

Erase F2 prompt

AA

Scan for F2 keystroke

AC

Enter SETUP

AE

Clear IN-POST flag

B0

Check for errors

B2

POST done, prepare for boot

B4

One short beep before boot

B5

Terminate quiet boot

B6

Check password (optional)

B8

Clear global descriptor table

B9

Clean up all graphics

BA

Initialize DMI parameters

BB

Initialize PnP option ROM's

BC

Clear parity checkers

BD

Display multi boot menu

BE

Clear screen optional

BF

Check virus and backup reminders

C0

Try to boot with Int 19

C1

Initialize POST error manager

C2

Initialize error logging

C3

Initialize error display function

C4

Initialize system error handler

E0

Initialize the chipset

E1

Initialize the bridge

E2

Initialize the processor

E3

Initialize system timer

E4

Initialize system I/O

E5

Check force recovery boot

E6

Checksum BIOS ROM

E7

Got to BIOS

E8

Set huge segment

E9

Initialize multiprocessor

EA

Initialize OEM special code

EB

Initialize PIC & DMA

EC

Initialize memory type

ED

Initialize memory type

EE

Shadow boot block

EF

System memory test

F0

Initialize interrupt vectors

F1

Initialize runtime clock

F2

Initialize video

F3

Initialize beeper

F4

Initialize BOOT

F5

Clear huge segment

F6

Boot to mini-DOS

F7

Boot to full DOS

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© 2005
Electrocution Technical Publishers 1007-246 Stewart Green SW Calgary
AB T3H 3C8 Canada (403) 539
1232