AMI Plus BIOS, commonly nicknamed as AMIBIOS Pre-Color between enthusiasts due to it predating the AMI Hi-Flex BIOS (which was the first version to have a colourful setup utility), is a version of AMIBIOS released by American Megatrends in 1987. It is the earliest version of AMIBIOS to include a built-in setup utility for configuring the CMOS settings without booting into a separate floppy disk for setup.
Plus BIOS was also the first and only version of AMIBIOS to include a built-in system diagnostics program, a limited version of AMIDIAG to be exact. Although AMIDIAG was not included with all versions of this BIOS, the ones that have it use "D" or "DE" for the CMOS setup type code in the BIOS string (see "BIOS string" section for further info).
Setup Utility
Very early releases of AMI Plus BIOS included a more limited setup utility which requires re-configuration of each setting in the utility entirely each time to change a setting. At some later point a new, more straightforward setup utility was included. Some board manufacturers like PCChips also used their own setup utility with AMI Plus BIOS, which looks different from AMI's utilities.