"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."


"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.... "

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

 Chips & Technologies
 Faraday A-Tease

Quadtel POST Codes

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

Version 3.07 (Phoenix)


02 Flag test
04 Register test
06 System hardware initialization
08 Initialize chipset registers
0A BIOS ROM checksum
0C DMA page register test
0E 8254 programmable interrupt timer test
10 8254 programmable interrupt timer initialization
12 8237 DMA controller test
14 8237 DMA controller initialization
16 Initialize 8259 programmable interrupt controller; reset math coprocessor
18 8259 programmable interrupt controller test
1A Memory refresh test
1C Base 64K RAM address test
1E Base 64K RAM memory test
20 Base 64K RAM test for 386 based systems
22 8742 keyboard controller self test
24 MC 146818 CMOS test
26 Start first protected mode test
28 Memory sizing test
2A Autosize memory chips
2C Chip interleave enable test
2E First protected mode test exit
30 Unexpected shutdown
32 System board memory size
34 Relocate shadow RAM if configured
36 Configure EMS system
38 Configure wait states
3A Retest 64K RAM base memory
3C CPU speed calculation
3E Get switches from 8042 keyboard controller
40 Configure CPU speed
42 Initialize interrupt vectors
44 Verify video configuration
46 Initialize video system
48 Test unexpected interrupts
4A Start second protected mode test
4C Verify LDT protected mode instruction
4E Verify TR protected mode instruction
50 Verify LSL protected mode instruction
52 Verify LAR protected mode instruction
54 Verify VERR protected mode instruction
56 Unexpected exception
58 Address line A20 test
5A Keyboard ready test
5C Determine AT or XT keyboard
5E Start third protected mode test
60 Base memory test
62 Base memory address test
64 Shadow memory test
66 Extended memory test
68 Extended address test
6A Determine memory size
6C Display error messages
6E Copy BIOS to shadow memory
70 8254 programmable interrupt timer clock test
72 MC 146818 real time clock test
74 Keyboard stuck key test
76 Initialize hardware interrupt vectors
78 Math coprocessor test
7A Determine serial ports available
7C Determine parallel ports available
7E Initialize BIOS data area
80 Determine floppy and hard disk controller
82 Floppy disk test
84 Hard disk test
86 External ROM scan
88 System key lock test
8A Wait for <F1> key pressed
8C Final system initialization
8E Interrupt 19 boot loader
B0 Unexpected interrupt before or after boot up

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16K XT


03 Test flag register
06 Test CPU register
09 Initialize system hardware
0C Test BIOS ROM checksum
0F Initialize 8237 DMA page register
12 Test 8237 DMA address and count registers
15 Initialize 8237 DMA controller
18 Test 8253 programmable interrupt timer
1B Initialize 8253 programmable interrupt timer
1E Start memory refresh test
21 Test base 64K RAM
24 Set up common interrupt temp stack
27 Initialize 8259 programmable interrupt controller
2A Test interrupt mask register
2D Test for unexpected interrupt
30 Test V40 DMA if present
31 Test for DDNIL bits if present
33 Verify system clock interrupt
36 Test keyboard
39 Set up interrupt table
3C Read system configuration switches
3F Test video
42 Determine serial ports available
45 Determine parallel ports available
48 Determine if game port available
4B Display copyright message
4E Calculate CPU speed
54 Test system memory
55 Test floppy drive
57 Initialize system before boot
5A Call interrupt 19 boot loader

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