AMIBIOS

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AMIBIOS is a personal computer BIOS developed by AMI (American Megatrends), which bought off it's rights from Access Methods Inc. in around 1986. Earliest known release of AMIBIOS is from 1985. While AMIBIOS is still in use on some industrial legacy machines to this day, it is no longer in use for most personal computers since early-2010s due to UEFI's increasing popularity. AMIBIOS has been mostly replaced by Aptio, the EFI/UEFI firmware developed by AMI.

Purchase from Access Methods

Main page: American Megatrends

Access Methods Inc. created AMIBIOS in 1985. Same year, Access Methods' owners (Subramonian Shankar and Pat Sarma) found a new company from the funds of Access Methods, called Quintessential Consultants Inc. (QCI). It then got renamed to American Megatrends Inc. (AMI) to keep the "AMIBIOS" acronym. American Megatrends then bought AMIBIOS from Access Methods in 1986.

List of known versions

All versions made before AMIBIOS Plus were first released by Access Methods, although some later cores of these versions (ones released after the purchase) had American Megatrends copyright as they were released by them.

Versions from AMIBIOS 2.2x all the way to AMIBIOS 6 and AMIBIOS 07.00.10 can often be identified by the date in the POST string, which actually does not change depending on the BIOS compile date (unlike AMIBIOS 07.00.xx and AMIBIOS 8) and were fixed dates from AMI indicating the core version release date. Although these dates were occasionally modified by OEMs or motherboard manufacturers, especially during the pre-WinBIOS (AMIBIOS 4) era.

Notice: Version labelling for very early AMIBIOS versions (pre-AMIBIOS Plus) is not certain due to lack of photos, ROM files and documents. As more information is available, these will be corrected.

List of known AMIBIOS versions
Version name First release date Known core dates POST screen (if available) Notes
"Rev-X2-03" (Actual core version unknown) 1985 or 1986(?) Not available Possibly earliest known version.
AMIBIOS 2.2x(?) 1986 061286050687070387013189022389021390060190 Assumed to be AMIBIOS 2.2x, might not be correct.
AMI Plus BIOS 1987 110387010388021988082588092588021589022589030389032089033089043089061389083089091589121589022090040990051390052390061390062590063090083090101590113090121590
AMI Hi-Flex BIOS 1990 111590 Programmer's guide to AMIBIOS book does not list releases with core dates before 031591 (March 15, 1991) as Hi-Flex, however earlier core dates do definitely exist. Not to be confused with the Hi-Flex Setup Utility on AMIBIOS 6 and 07.00.10 (although the setup utility was named after it). Hi-Flex might also be AMIBIOS 3.
AMI WinBIOS (AMIBIOS 4) 1993 121593 Often referred to as AMI WinBIOS, not to be confused with the WinBIOS Setup Utility on AMIBIOS 5 and 6 (although that was named after it). Subcore 082594 also exists, although it's assumed to be a re-badge of subcore 072594 modified by some OEMs due to lower core version compared to 081594.
AMIBIOS 5 1994 101094
AMIBIOS 6 1995 071595 071597071599051100
AMI eBIOS Version 1 Unknown Unknown Not available. Currently no information is known, might not exist but assumed to be due to eBIOS 02.00.xx.
AMIBIOS 07.00.xx 1999 Not available Not to be confused with AMIBIOS 7 (07.00.10, subcore date 040201). Probably a public beta release for AMIBIOS 8.
AMI eBIOS 02.00.xx 2000 or 1999 Not available Assumed to be a variant of AMIBIOS 07.00.xx for embedded systems. Not much is known about it.
AMIBIOS 7 (07.00.10) 2001 040201 Not to be confused with AMIBIOS 07.00.xx. Assumed to be an update for the AMIBIOS 071595 codebase.
64-Bit AMIBIOS Version 1 2001(?) Unknown Not available. Currently no information is known, might not exist but assumed to be due to 64-Bit AMIBIOS 02.00.00.
AMIBIOS 8 2001 Not available

Last standalone version of AMIBIOS
64-Bit AMIBIOS 02.00.00 2003(?) Not available Not available. Assumed to be a variant of AMIBIOS 8 or 07.00.xx for Itanium based servers. Only known instance is on the SuperMicro MBD-i2DML-8G2-O Intel Itanium motherboard.
AMIBIOS 9 Unknown Not available Not available. Only some strings (found in a specific version of vmvp.exe for Hyper-V in Microsoft Windows 7 SP1) are available, assumed to be a special version or fork for Microsoft Hyper-V, or possibly the name given to emulated BIOS for CSM mode in AMI Aptio.

BIOS string

The BIOS string for AMIBIOS was first introduced with AMIBIOS 2.2x for easy identification of each BIOS release and is often seen during POST at the very bottom of the screen. The string format was changed a couple times with new core versions of AMIBIOS. Known codes for some identification sections are given in the List of codes for BIOS strings section.

AMIBIOS 2.2x

MMMM: Manufacturer/OEM identification code, SSSSSS: BIOS subcore release date

MMMM-SSSSSS

Example string: 1406-061286

This string is for a 06/12/86 (June 12, 1986; date is in American format) dated subcore BIOS for Flying Triumph Co. Ltd. ("1406").

AMI Plus BIOS

D: CMOS setup type, CCC: Chipset type, MMMM: Manufacturer/OEM identification code, SSSSSS: BIOS subcore release date, KK: Keyboard controller (KBC) ID (with second character indicating the model).

DCCC-MMMM-SSSSSS-KK

Note: The CMOS setup type code can be two characters for "DE" in case the BIOS contains both extended setup and built-in diagnostics.

Example string: D286-1277-043089-K0

This string is for a 04/30/89 (April 30, 1989; date is in American format) dated subcore AMI Plus BIOS with regular CMOS setup and built-in diagnostics ("D") for a machine with a discrete i286 logic ("286") and a default/unknown keyboard controller (K"0") made by Trangg Bow Co. ("1277").

Later BIOS versions

C: Processor architecture, R: ROM size, MMMM: Manufacturer/OEM identification code, FFFFFFFF: BIOS feature identification (often 00101111), SSSSSS: BIOS compile date OR subcore release date, DDDDDDDD: BIOS identifier, Project: BIOS project ID (no maximum characters), K: Keyboard controller (KBC) ID

CR-VVVV-00MMMM-FFFFFFFF-SSSSSS-DDDDDDDD-Project-K

Note: The project ID section is only present on late AMIBIOS 6 and later releases. The keyboard controller ID is also not used since AMIBIOS 07.00.xx.

Example string: 61-1108-001169-00101111-071595-440BX/ZX-1440B000-H

This string is for a 11.08 revision ("1108") 128 KB ("1") size AMIBIOS 6 ("071595", main subcore for it) for a motherboard for 686 architecture processors ("6") with Intel 440BX or 440ZX chipset ("440BX/ZX") and an AMIKEY-2 clone keyboard controller ("H") made by MSI ("1169").

List of known codes for BIOS strings

Click "Expand" to view.

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This page was last edited on 15 December 2023, at 18:01.