IBM PC-DOS

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**PC-DOS** <tr><td colspan="2" style="text-align: center;">Image:PC DOS Logo.jpg</td></tr><tr><td colspan="2" style="text-align: center;">Image:PC DOS Command Window.gif
A typical command line in PC DOS.</td></tr><tr><td style="text-align: left;">Company/
developer:</td><td>IBM</td></tr><tr><td>**OS family:**</td><td>DOS</td></tr><tr><td>**Source model:**</td><td>Closed source</td></tr><tr><td>**Latest stable release:**</td><td>7.0 revision 1 (a.k.a. PC DOS 2000) / August, 1996</td></tr><tr><td>**Default user interface:**</td><td>CLI</td></tr><tr><td>**License:**</td><td>Proprietary</td></tr><tr><td>**Working state:**</td><td>Historic</td></tr>

IBM PC-DOS was one of three major operating systems that dominated the personal computer market from about 1985 to 1995. The original 1981 arrangement between IBM and Microsoft was that Microsoft would provide the base product and that both firms would work on developing different parts of it into a more powerful and robust system, and then share the resultant code. MS-DOS and PC DOS were to be marketed separately: IBM selling to itself for the IBM PC, and Microsoft selling to the open market. ThinkPad products currently have a copy of the latest version of PC DOS in their Rescue and Recovery partition.

[edit] Windows

In the meantime, end users and software developers shifted from DOS to Windows, which became an operating system of its own, and, since the introduction of 32-bit File Access in version 3.11, was merely using DOS as a boot loader. The next release, Windows 95, introduced long file names through the VFAT file system, which required modifying all MS-DOS utilities to support this feature. Hypothetically, it was still possible to start Windows from a non-Microsoft version of DOS, but then during the Windows session, the foreign DOS utilities would not see long file names and consequently could not preserve them during writing operations. Windows 95 still allowed dual-booting with MS-DOS on the same disk partition, whether a Microsoft or competing release, but it made little sense to the user and could destroy long file names. For example, OS/2 3.0 would automatically run the CHKDSK utility during installation and destroy the Windows 95 long file names.

The final release, PC DOS 2000, found its niche in the embedded software market and elsewhere. This version dealt with the Year 2000 problem. Versions 7 and 2000 supported a diskette format known as XDF, which allowed for more data to be written to a standard floppy disk than usual.

[edit] Versions

Some information about previous versions:

IBM PC-DOS 2.0 fit on two 180K single-sided 5.25-inch floppy diskettes, (or one double-sided 360K disk) and was copyrighted in 1983. Maximum disk partition size native to OS: 10MB.
IBM PC-DOS 3.2 required 128KB RAM, fit on one 720KB DSDD diskette, had file dates 12/30/1985. COMMAND.COM is 23,791 bytes and the box says the operating system was sold "As-Is". Maximum disk partition size native to OS: 32MB.
PC-DOS 4.01 fit on two 3.5-inch DD diskettes (720K) and required 256KB (360KB with SHELL option). The operating system file COMMAND.COM is 37,637 bytes. Maximum disk partition native to OS: 2000MB.