AMIBIOS

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AMIBIOS is a personal computer BIOS developed by AMI (American Megatrends), which has bought it's rights from Access Methods Inc. in around 1986. Earliest known mentions of AMIBIOS are from 1985, with the earliest known version likely being released around that time.

While it is still used on some industrial/embedded legacy computers to this day (such as the ones based on the Vortex86 SoC), it has been fully phased out on consumer desktops, laptops and workstations in favor of (U)EFI-based solutions such as Aptio (which is it's successor), InsydeH2O and Phoenix SecureCore. However, most earlier instances of Aptio released still included an embedded version of AMIBIOS 8 as a component module for CSM/legacy boot. With CSM being discontinued by Intel in 2020 however, the module is no longer present in recent versions of it.[1]

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 POST screen (if available) Notes
"Rev-X2-03" (Actual core version unknown) 1985 or 1986(?)' Possibly earliest known version.
AMIBIOS 2.2x(?) 1986 Assumed to be AMIBIOS 2.2x, might not be correct.
AMI Plus BIOS 1987 Unofficially also called as AMI Pre-Color BIOS by some enthusiasts (since it came before Hi-Flex, which had a colorful setup utility).
AMI Hi-Flex BIOS 1990 Not to be confused with the Hi-Flex Setup Utility on AMIBIOS 6 and 7 (07.00.10), which was named after it. Unofficially also called AMI Color BIOS by some enthusiasts (due to its colorful setup utility). It might have also been considered as AMIBIOS 3 internally.
AMI WinBIOS (AMIBIOS 4) 1993 Often referred to as AMI WinBIOS, not to be confused with the WinBIOS Setup Utility on AMIBIOS 5 and 6, which was named after it). Often known with the core date 121593 in string, however other core dates also exist.
AMIBIOS 5 1994 Often known with the core date 101094 in string.
AMIBIOS 6 1995 Often known with the core date 071595 in string, however other core dates also exist.
AMI eBIOS Version 1 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 to be confused with AMIBIOS 7 (07.00.10, subcore date 040201). Probably a public beta release which later became AMIBIOS 8.
AMI eBIOS 02.00.xx 2000 or 1999 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 Not to be confused with AMIBIOS 07.00.xx. Often known with the core date 040201 in string. Assumed to be an update based on the AMIBIOS 6 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

Last standalone version of AMIBIOS
64-Bit AMIBIOS 02.00.00 2003(?) 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. 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.

  1. ↑ https://www.intel.com/content/www/us/en/content-details/630266/removal-of-legacy-boot-support-for-intel-platforms-technical-advisory.html | Note: Although this document was published in 2023, it clearly mentions legacy boot being discontinued in 2020.
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This page was last edited on 28 April 2024, at 10:34.