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: Not much information is known about very early AMIBIOS versions (pre-AMIBIOS Plus) due to lack of photos, ROM files and documents. Various information regarding these early versions are assumed based on copyright dates, incomplete documents and overall behaviour and look of these BIOSes. As more information becomes available, the assumed information will be corrected unless they are actually correct.
| Main core version | Main core release date | Earliest known subcore date | Last known subcore date | Notes |
|---|---|---|---|---|
| AMIBIOS 1.xx(?) | 1985 | Unknown/No subcore dates used | Unknown/No subcore dates used | No footage, manual or ROM file exists as of currently. Might have also been labelled AMIBIOS Rev-X1-xx. |
| AMIBIOS 2.0x | 1985 or 1986 | No subcore dates used | No subcore dates used | Also labelled as AMIBIOS Rev-X2-0x. |
| AMIBIOS 2.1x | 1985 or 1986 | Unknown/No subcore dates used | Unknown/No subcore dates used | No footage, manual or ROM file exists as of currently. Might have also been labelled AMIBIOS Rev-X2-1x. |
| AMIBIOS 2.2x | 1986 | 061286 (June 12, 1986) | 013189 (January 31, 1989) | |
| 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) | 072594 (July 25, 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). |
| 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 | |
| AMIBIOS 7 (07.00.10) | 2001 | 040201 (April 2, 2001) | None (040201 only) | |
| AMIBIOS 8 | 2001 | No subcore dates used | No subcore dates used |
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 also given below.
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 (Early)
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
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").
AMI Plus BIOS (Late) and 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.
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").