IBMDOS.COM (second in the list ofCOM files) inIBM PC DOS 1.0.IBMDOS.COM is the filename of theIBM PC DOS andDR-DOSkernel. Loaded and initially invoked by theDOS BIOS inIBMBIO.COM during the boot process,[1] it contains the hardware-independent parts of the operating system, including the embeddedFAT12,FAT16 and, in newer versions, theFAT32file system code, as well as the code to provide theDOS API to applications.
The file exists inPC DOS 1.0 to7.10 andDR DOS 5.0 and higher[2] (except for DR-DOS 7.06), withMS-DOS usingMSDOS.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.[2][1] (For compatibility purposes with some DOS applications the IBMDOS.COM file name was briefly also used by the IBM version ofOS/2 1.0, where it resembled theOS2DOS.COM OS/2 kernel file as used byMicrosoft.)
By default, the file is located in theroot directory of the bootable drive/partition (normally C:\) and has thehidden,read-only, andsystemfile attributes set.[2] As IBMDOS.COM is a binary image containing executable code rather than a trueCOM-style program, thehidden 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 forDR-DOS 7.02 and higher, because under these systems the file is afat binary also containing a tiny COM-style stub just displaying some version info and exiting gracefully when loaded inappropriately.[3][1]
InDigital Research terminology, the kernel component of the operating system is called theBDOS (Basic Disk Operating System),[1] a term originally coined byGary Kildall in 1975 forCP/M,[4] but which is continued to be used in all other DRI operating systems (except forConcurrent DOS 286 andFlexOS). Microsoft has usedthis name as well when referring to the kernel of theMSX-DOS operating system. TheFAT file system specific code is called the FDOS in DRI terminology.
[…] In case no source drive and path is given, SYS will assume the system files to reside on the drive containing the SYS.COM program. If this is a local drive, it will try to locate them in the root of this drive, otherwise it will search for them in the SYS.COM directory itself. […] /K Keep original attributes of system files (else set to +RSH). […] /3 or /5 Name either DRBIOS.SYS/DRBDOS.SYS or IBMBIO.COM/IBMDOS.COM. […]
An excerpt of the BDOS.PLM file header in thePL/M source code ofCP/M 1.1 orCP/M 1.2 forLawrence Livermore Laboratories (LLL):
[…]/* C P / M B A S I C I / O S Y S T E M (B I O S) COPYRIGHT (C) GARY A. KILDALL JUNE, 1975 */[…]/* B A S I C D I S K O P E R A T I N G S Y S T E M (B D O S) COPYRIGHT (C) GARY A. KILDALL JUNE, 1975 */[…]
 | Thisoperating-system-related article is astub. You can help Wikipedia byadding missing information. |
