DOS: A history by the numbers
In 1979 Seattle Computer Products (
Time passed and still no 8086 CP/M appeared. Oh dear.
Interestingly enough, part of the deal
Microsoft's defense was the deal was for versions based on
DOS 1.0, not the post-2.0 rewrite.
Microsoft released this update to DOS 1.0 May 1982. It fixed a number of bugs in DOS 1.0. Its major enhancement was support for 320KB double-sided floppy disk drives. Previous to DOS 1.1, double-sided floppies were only usable by turning the disk over to the other side. An OEM version for a Zenith PC was released as DOS 1.25 (aka Z-DOS).
COMMAND.COM is 4,959 bytes in size.
DOS 2.0 was a complete rewrite of the DOS 1.1 code. It was
released in March 1983. It was created to address
COMMAND.COM is 17,792 bytes in size.
In September 1984 Microsoft released DOS 3.0 to support
COMMAND.COM is 22,042 bytes in size.
Microsoft released DOS 3.1 in November 1984. It was chiefly released to support businesses that wanted to connect PCs to LANs. Microsoft's solution was adding something called the Network Redirector to DOS 3.1. It allowed one to access a network as a drive letter, instead of having to use special software to transfer files between the PC and the server.
COMMAND.COM is 23,210 bytes in size.
Microsoft released DOS 3.2 in December 1985. It supported
3.5" 720Kb Floppy drives. This was the first version Microsoft sold
directly to consumers. All previous versions came preinstalled by the OEM.
DOS 3.2 was the standard for a long time (until 1987 with the release of DOS
COMMAND.COM is 23,612 bytes in size.
Microsoft released DOS 3.3 in April 1987. It was released
DOS 3.3 became the gold-standard of DOS ... the DOS people ran back to after the disastrous releases of DOS 4.0.
Digital Research got into the DOS game at this time, releasing
DR-DOS 3.31 (there were no 3.0-3.2 versions). Some viewed it as a better DOS
than DOS. Some versions of DR-DOS were also bundled with the
COMMAND.COM is 25,276 bytes in size.
Microsoft released DOS 4.0 in July 1988. It was the
super-buggy follow on to DOS 3.3. DOS 4.0 was supposed to allow
DOS 4.0 introduced the first MS DOS shell interface. DOS 4.01 was the first version to support Russian Cyrillic characters. The few people that actually slogged through with 4.01 were offered an upgrade to a 4.01A release in April 1989. The A version supported larger hard drives.
There's a theory that, due to the public outcry over DOS 4.0, MS has developed a superstition about naming anything 4.0 anymore. For example, it wasn't Windows 4.0, it was Windows 95.
COMMAND.COM is 37,254 bytes in size.
By the time Microsoft released DOS 5.0 in April 1991, it had learned something about software testing in the intervening three years. DOS 5.0 went through the largest beta testing in history (up until that time).
DOS 5.0 could now load itself in high memory area (
DOS 5.0 added the undelete utility and a disk cache utility (which ended up causing Microsoft a new set of problems). It added the SETVER command. Lots of programs checked to see what DOS version was running before running. Earlier versions of DOS had major backward compatibility problems and programmers had to check DOS versions before running. Short sighted programmers, for some reason, never envisioned DOS 5.0. Programs perfectly compatible would not run.
Microsoft replaced GW-BASIC with QBASIC. It added the delightful DOSKEY command.
DOS 5.0 also added man pages for its commands.
COMMAND.COM is 47,987 bytes in size.
Microsoft released DOS 6.0 in August 1993. Although a full revision number, it's questionable whether DOS 6.0 justified a revision from 5.0 to 6.0. There were rumors DOS 6.0 would be a full 32-bit DOS but those proved groundless. It's likely Microsoft called it DOS 6.0 instead of DOS 5.1 or 5.5 because Digital Research had released DR-DOS 6.0.
DOS 6.0 incorporated a lot of utilities that previously
had been the domain and cash cow of third-party software makers. DOS 6.0
added a virus scanning utility and featured a command called MEMAKER which
took a lot of the guess work out of editing your AUTOEXEC.BAT and CONFIG.SYS.
A couple new file commands were added. DELTREE now let you delete an entire
group of folders and files.
The most controversial addition was Microsoft's DoubleSpace utility. Microsoft had for a while been negotiating a take over of Stac Electronics, maker of the STACKER disk compression utility. After the deal fell apart, Microsoft did what it typically did if you don't sell your software company to Microsoft for Bill-favorable terms. MS threw 200 programmers on a project to create their own version. Microsoft's version DoubleSpace was released with DOS 6.0. Even before DOS 6.0's actual release, Stac launched a lawsuit.
The Stac lawsuit wasn't the only problem DoubleSpace was causing Microsoft. Users were complaining the utility was eating files. Microsoft released DOS 6.2 in November 1993 to address these concerns. DOS 6.2 included DoubleGuard, which ensured memory wasn't corrupted before writing data to the disk. It also included ScanDisk to scan and repair disk errors. Finally, DOS 6.2 gave users the ability to decompress their hard drive, should they decide DoubleSpace was more trouble than it was worth.
In February 1994, a court ruled Microsoft had illegally used Stac's disk compression algorithm. MS was ordered to pay Stac $120 million. However, Microsoft launched a counter-suit against Stac. A court found Stac too had misappropriated Microsoft "preload" technology. Stac was ordered to pay Microsoft $13.7 million. (It's interesting to note that Stac made in a year what Microsoft made in 4 hours.)
To comply with the court order, Microsoft had to release DOS 6.21 in March 1994, which was essentially DOS 6.2 sans any form of disk compression. As well, Microsoft was required to make reasonable efforts to recall all version of DOS 6.x that featured the compression. Cha ching!
Before the recall was to take effect, Microsoft and Stac surprised the computer world by announcing a cross-licensing deal. Both agreed to not pursue the court awards. Microsoft would pay Stac a licensing fee of $1 million a month for 43 months and buy $40 million worth of Stac stock.
Microsoft eventually released DOS 6.22 in April 1994 with new disk compression software called DriveSpace. Although Microsoft had a licensing deal with Stac, DriveSpace used a public-domain compression algorithm.
COMMAND.COM is 52,925 bytes in size.
-- Karl Mamer