The real-mode portion was meant to provide backward-compatibility with existing operating systems such as DOS, and therefore was named "CBIOS" (for Compatibility BIOS), whereas the "ABIOS" (for Advanced BIOS) provided new interfaces specifically suited for multitasking operating systems such as OS/2.
Options on the IBM PC and XT were set by switches and jumpers on the main board and on peripheral cards.
Starting around the mid-1990s, it became typical for the BIOS ROM to include a "BIOS configuration utility" (BCU) or "BIOS setup utility", accessed at system power-up by a particular key sequence.
So CPM on the IMSAI was a joint effort between Glenn and Gary.
Glenn […] would be talking with Gary, and he started twisting Gary's arm.
In principle, the hardware dependent portions of CP/M were concentrated in the BIOS, thus allowing Glenn, or anyone else, to adapt CP/M to the Imsai equipment.
Imsai was subsequently licensed to distribute CP/M version 1.3 which eventually evolved into an operating system called IMDOS.The disk was supplied with the computer, and if it was lost the system settings could not be changed.A modern Wintel-compatible computer provides a setup routine essentially unchanged in nature from the ROM-resident BIOS setup utilities of the late 1990s; the user can configure hardware options using the keyboard and video display.Little attention was paid to CP/M for about a year.In my spare time, I worked to improve overall facilities […] By this time, CP/M had been adapted for four different controllers.He said, "Hey Gary, why can't we run this in this IMSAI?