IBMBIO.COM
IBMBIO.COM is a system file in the IBM PC DOS and DR DOS operating systems . In the newer versions of MS-DOS , the corresponding file is called IO.SYS . In DR-DOS versions 3.31 to 3.41 the file is called DRBIOS.SYS.
The first versions of MS-DOS were also used by IBMBIO.COM. While Microsoft merged the functions of IO.SYS and MSDOS.SYS in the IO.SYS file from MS-DOS 7.0 onwards, IBM kept the separation up to the last version of PC-DOS. The first versions of OS / 2 also used IBMBIO.COM for the start.
function
During the boot process of PCs , the first sector ( boot sector ) of the boot disk is loaded into memory and the following actions are carried out:
- Loads the remainder of itself that is not in the first three sectors of the boot volume into memory.
- Initializes the standard device drivers one after the other : ( system console , data carrier, serial interface , all others). From this point on, all standard devices are available.
- Loads the DOS kernel and calls the initialization routine. The kernel is stored in the IBMDOS.COM file.
- load into memory and execute COMMAND.COM
With DR-DOS, the first step is skipped because a DR-DOS boot sector searches for IBMBIO.COM (or DRBIOS.SYS) in the root directory and loads it into memory. It is not necessary under DR-DOS that this file is in a fixed physical position.