IBM PC-DOS

IBM PC-DOS was an IBM branded version of MS-DOS licensed from Microsoft for use on the IBM PC system. Versions of PC-DOS paralleled that of MS-DOS up until version 6.1, where PC-DOS was independently maintained by IBM up until 7.1, the last version. Although not the only OS available for the IBM PC when it came out, it quickly became popular due to its low cost in comparison to the others. Its direct competitors on the PC at the time were CP/M-86 and UCSD p-System. The major differences between PC-DOS and MS-DOS were only in terms of driver support and built in programs until version 6.1 where development diverged.

The first version of PC-DOS was released in August 1981 with the IBM PC. The last version released by IBM was PC-DOS 7.1, which had releases all the way up until 2003. This last version of DOS is still in use by some hardware developers usually embedded into recovery tools and BIOS flashers.

This OS does not have a GUI. It uses a command line interface, however PC-DOS 4 and later, like MS-DOS, also included the optional graphical DOSShell program. Like other DOSes, third party GUIs can be installed.

1.x
IBM PC-DOS 1.0 was a port of 86-DOS purchased by Microsoft in 1981 for use on the IBM PC. This version of DOS resembles that of CP/M at the time. Only 160kB 5.25 inch (134mm) floppies were supported. Directory support did not exist with this version of DOS.
 * 0.90
 * 1.00
 * 1.10

2.x
PC-DOS 2.0 was IBM's retail version of MS-DOS branded specifically towards IBM Machines. Version 2.0 of PC-DOS introduced various features inspired of Xenix, a varient of Unix sold by Microsoft. These features included file handles.
 * 2.00
 * 2.10

3.x
PC-DOS 3.x was introduced for IBM's 286 based AT computer. It adds support for IBM's 1.2mb floppy drive, hard disk partitions up to 32mb, and adds features for use with networking.
 * 3.00
 * 3.10
 * 3.20
 * 3.30

4.x
IBM DOS 4.00 was IBM's first in-house development effort with DOS. Prior to this release, all DOS code had been managed by Microsoft on IBM's behalf (hence the parallel releases). With this version, IBM re-engineered the source and added their own enhancements. PC-DOS 4.00 adds support for drives up 2 gigabytes and a graphical DOS shell. The initial release of IBM PC-DOS 4.00 was extremely buggy. It was quickly followed up by a 4.01 update.
 * 4.00
 * 4.01

5.x
Over all, PC-DOS 5 was much improved over DOS 4. It reduced base 640k memory usage by making use of HMA on 286+ CPUs.
 * 5.00
 * 5.02

6.x
IBM skipped version 6.0 to avoid confusion with MS-DOS 6.0.

PC-DOS 6.1 is quite different from MS-DOS. Instead of Symantec tools, PC-DOS bundles additional disk utilities from Central Point Software. It also bundles IBMs own Antivirus software, and SuperStore disk compression.
 * 6.10
 * 6.30

7.x
PC-DOS 7, AKA "IBM PC DOS 7.00, revision 0", adds the REXX Programming language, XDF 1.86MB 3.5" floppy disk support, and Stacker Disk compression.
 * 7.00

2000
PC-DOS 2000 is a minor update to PC-DOS 7.0 that fixes Y2K bugs. It is marketed as "PC-DOS 2000" but it reports itself as "IBM PC DOS 7.00, revision 1".

7.0/2000 was the last complete release. Although some embedded products were released with portions of "PC-DOS 7.1" that added Fat32 support.
 * 2000