IBMBIO.COM

It also loads the DOS kernel (IBMDOS.COM) and optional pre-loadable system components (like for disk compression or security),[1][2] displays boot menus, processes configuration files (like CONFIG.SYS) and launches the shell (like COMMAND.COM).

[3][nb 1] Under PC DOS, the system attribute is set in order to mark the file as non-movable, a restriction technically not necessary under DR-DOS.

[7][5][6][8][3] As IBMBIO.COM is a binary image containing executable code rather than a true COM-style program, the hidden attribute is set to keep the file from being accidentally invoked at the command prompt, which would lead to a crash.

[5] This is no longer necessary for DR-DOS 7.02 and higher, because under these systems the file is a fat binary also containing a tiny COM-style stub just displaying some version info and exiting gracefully when not being loaded by a boot sector.

The term BIOS was originally coined by Gary Kildall in 1975 for CP/M,[15][16][17][18][19][20] but is also used to describe a similar component or layer in other operating systems by Digital Research, IBM, Microsoft and many others.