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.
Starting:-The first commercial licensing of CP/M took place in 1975 with contracts between Digital Systems and Omron of America for use in their intelligent terminal, and with Lawrence Livermore Laboratories where CP/M was used to monitor programs in the Octopus network.
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 name originates from the Basic Input/Output System used in the CP/M operating system in 1975.