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 the updated cores 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 their subcore dates, which actually does not change depending on the BIOS compile date (unlike other AMIBIOS 07.00.xx releases and AMIBIOS 8) and were fixed dates from AMI indicating the subcore release date. The subcore date can be found in the BIOS string during POST (refer to the BIOS string section of this page for further information). Please note that the core dates were occasionally modified by OEMs or motherboard manufacturers, especially during the pre-WinBIOS (AMIBIOS 4) era. Full list of subcores are available on the main page for each of these BIOS versions.

Notice: Core version labelling for very early AMIBIOS versions (pre-AMIBIOS Plus) is unknown due to lack of photos, ROM files and documents. As more information is available, these will be corrected.

List of known AMIBIOS versions
Main core version Main core release date Earliest known subcore date Last known subcore date POST screen Notes
"Rev-X2-03" (Actual core version unknown) 1985 or 1986(?) No subcore dates used No subcore dates used Possibly earliest known version.
AMIBIOS 2.2x(?) 1986 061286 (June 12, 1986) 013189 (January 31, 1989) Assumed to be AMIBIOS 2.2x, might not be correct.
AMI Plus BIOS 1987 110387 (November 3, 1987) 030891 (March 8, 1991)
AMI Hi-Flex BIOS 1990 111590 (November 15, 1990) 011094 (January 10, 1994) 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 (December 15, 1993) 081594 (August 15, 1994) 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 (October 10, 1994) None (101094 only)
AMIBIOS 6 1995 071595 (July 15, 1995) 071599 (July 15, 1999)
AMIBIOS 07.00.xx 1999 No subcore dates used No subcore dates used Not to be confused with AMIBIOS 7 (07.00.10, subcore date 040201). It is probably a public beta release for AMIBIOS 8.
AMIBIOS 7 (07.00.10) 2001 040201 (April 2, 2001) None (040201 only) Not to be confused with AMIBIOS 07.00.xx
AMIBIOS 8 2001 No subcore dates used No subcore dates used Last version of AMIBIOS

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 20 December 2022, at 10:04.