Those BIOS Numbers

What do all those numbers and letters
on your system BIOS stand for?

BIOS (Basic Input/Output System) intricacies and other such funness. All those numbers and letters, seemingly irrelevant, are in fact
trying to tell us something. The AMI BIOS ID below was viewed from a Microcomputer Hardware classroom PC (a wee bit older model)

The BIOS is generally a separate ROM chip from the other disks. It’s a software program, usually built on a flash chip these days. Flash BIOS’s can be updated easily. The updates generally are available either from the motherboard manufacturer or the computer/laptop company.

BIOS defined:
AMI BIOS ID – 40-0100-001437-00101111-080893-4386-F

4: means it’s a 80486

0: means the BIOS size is 128k

01: is the Major version number

00: is the Minor version number

001437: is the Reference number

0: Halt on POST Error= Off

0: Initialize CMOS in every boot= Off

1: Block pins 22 & 23 of keyboard controller= On

0: Mouse Support in BIOS/keyboard controller= Off

1: Wait for [F1] if errors found= On

1: Display floppy error during POST= On

1: Display video error during POST= On

1: Display keyboard error during POST= On

08: BIOS Date (Month)

08: BIOS Date (Day)

93: BIOS Date (Year = 1993!)

4386: BIOS name/Chipset ID F: Keyboard controller Version number


Why update the System BIOS? These updates often fix problems and bugs. For example, I went to Dell’s support/download web site for a specific laptop (not to be confused with the 1993 BIOS mentioned above). After typing in my system Service Tag, I browsed for updates, specifically BIOS ones. They call them FlashBIOS updates. After taking note of which BIOS version the laptop was currently using (as seen on boot for a few seconds before the OS begins loading, or by going into the BIOS set up itself), I noticed the laptop could be updated with “A15”. Here is what Dell had to say:

“The BIOS release has been validated on the following operating systems: 1. Microsoft Windows 95 v4.00.950B 2. Microsoft Windows NT 4.0 SP5 3. Microsoft Windows NT 4.0 SP6 4. Microsoft Windows 98 Second Edition APM only 5. Microsoft Windows 2000 ACPI 6. Microsoft Windows Millennium ACPI

The following updates were made to the A14 BIOS to create A15:

Issues Fixed:
1. Fixed issue in which some batteries may permanently stop charging.
2. Fixed issue in which Remote BIOS Update may fail to update the BIOS.
3. Fixed issue in which the system intermittently fails to detect when a new battery is inserted.
4. Fixed issue in which System Setup may take 7 seconds to recognize a new battery.
5. Fixed issue in which the system may fail to complete POST if the battery is not responding.
6. Fixed failure to log on to a Boot Server when booting from a PXE-enabled CardBus NIC.
7. Fixed issue seen on systems equipped with SpeedStep-capable processors in which the processor runs at its low speed during boot, regardless of the SpeedStep setting in System Setup.
8. Fixed video corruption seen when entering System Setup with more than 256MB RAM installed.
9. Fixed issue seen when using Safeguard Easy security software in which a “No bootable devices” error is seen after entering the correct password.

1. Optimized the battery charging algorithm.”


For general BIOS flash upgrade instructions to a system, go to the following link and peruse at your leisure:


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