AMIBIOS Rev-X2-03

POST screen of AMIBIOS 2.03

AMIBIOS 2.0x is the second main release of AMIBIOS, made by Access Methods (which then sold AMIBIOS to American Megatrends). AMIBIOS 2.0x also has been labelled as AMIBIOS Rev-X2-0x, with x indicating subversion. AMIBIOS 2.0x is assumed to be released in 1985 or early-1986.

So far, the only known instance of AMIBIOS 2.0x is AMIBIOS 2.03 (labelled as Rev-X2-03) seen on an IBM XT clone motherboard demonstrated by the YouTube channel Dfgrt924. This is believed to be the earliest known version of AMIBIOS with proof to confirm it's existence.

POST screen

The POST screen is different from all other known versions of AMIBIOS. The 8088-BIOS text at the top and the memory test counters all look different. This version also has two memory counters (one for base system memory and other for expanded memory that could be additionally installed), instead of only one as seen in newer versions.

This version also seems to lack a proper BIOS string, while AMIBIOS 2.2x already had a string, indicating the string was introduced with either 2.1x or 2.2x. It says "Rev-X2-03" where the string would go with future versions.

The BIOS also lacks a setup launch prompt, which is usual for early IBM PC compatible BIOSes. Built-in setup utilities started becoming common in around 1987.

Boot error messages

There are two boot errors seen in the demonstration, the first error message that reads Drive not ready Insert diskette in A: Press any key ..... appears when a floppy drive is either not installed or can't boot to a disk yet. While the second Boot failure Insert diskette in A: Press any key ..... error appears when there is not a valid boot disk in the drive. These messages are similar to the ones seen on newer AMIBIOS versions, although slightly different.