IBMDOS.COM is the filename of the

IBM PC DOS IBM PC DOS (an acronym for IBM Personal Computer Disk Operating System),Formally known as "The IBM Personal Computer DOS" from versions 1.0 through 3.30, as reported in those versions' respective COMMAND.COM outputs also known as PC DOS or IBM ...

and

DR-DOS DR-DOS is a disk operating system for IBM PC compatibles, originally developed by Gary A. Kildall's Digital Research, Inc. and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86. Upon its introduction in 198 ...

kernel. Loaded and initially invoked by the DOS BIOS in IBMBIO.COM during the boot process, it contains the hardware-independent parts of the operating system, including the embedded

FAT12 File Allocation Table (FAT) is a file system developed for personal computers and was the default file system for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on ...

FAT16 File Allocation Table (FAT) is a file system developed for personal computers and was the default file system for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on Ha ...

and, in newer versions, the

FAT32 File Allocation Table (FAT) is a file system developed for personal computers and was the default file system for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on ...

file system code, as well as the code to provide the DOS API to applications. The file exists in PC DOS 1.0 to 7.10 and DR DOS 5.0 and higher (except for DR-DOS 7.06), with

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few op ...

using MSDOS.SYS (from version 1.10 to 6.22) for the same purpose. DR DOS 3.31 to 3.41 used the equivalent DRBDOS.SYS file instead. (For compatibility purposes with some DOS applications the IBMDOS.COM file name was briefly also used by the IBM version of OS/2 1.0, where it resembled the OS2DOS.COM OS/2 kernel file as used by

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

.) By default, the file is located in the

root directory In a Computing, computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most Directory (computing), directory in a hierarchy. It can be likened to the trunk of a Tree (data st ...

of the bootable drive/partition (normally C:\) and has the ''hidden'', ''read-only'', and ''system''

file attribute File attributes are a type of metadata that describe and may modify how files and/or directories in a filesystem behave. Typical file attributes may, for example, indicate or specify whether a file is visible, modifiable, compressed, or encrypte ...

s set. As IBMDOS.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. This is not 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 loaded inappropriately. In

Digital Research Digital Research, Inc. (DR or DRI) was a privately held American software company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser ...

terminology, the kernel component of the operating system is called the BDOS ( Basic Disk Operating System), a term originally coined by

Gary Kildall Gary Arlen Kildall (; May 19, 1942 – July 11, 1994) was an American computer scientist and microcomputer entrepreneur. During the 1970s, Kildall created the CP/M operating system among other operating systems and programming tools, and s ...

in 1975 for

CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/Intel 8085, 85-based microcomputers by Gary Kildall of Digital Research, Dig ...

, but which is continued to be used in all other DRI operating systems (except for

Concurrent DOS 286 Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers. An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by ...

and

FlexOS FlexOS is a discontinued modular real-time multiuser multitasking operating system ( RTOS) designed for computer-integrated manufacturing, laboratory, retail and financial markets. Developed by Digital Research's Flexible Automation Business ...

). Microsoft has used this name as well when referring to the kernel of the

MSX-DOS MSX-DOS is a discontinued disk operating system developed by Microsoft's Japan subsidiary for the 8-bit home computer standard MSX, and is a cross between MS-DOS v1.25 and CP/M-80 v2.2. MSX-DOS MSX-DOS and the extended BASIC with 3½-in ...

operating system. The

FAT In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

file system specific code is called the FDOS in DRI terminology.

References

DOS kernel DOS files {{operating-system-stub

See also

References