Dos History, Author Unknown

DOS history

DOS has a very interesting story to tell. Lessons about under-estimation, greed, , the raise of Microsoft to what it is now, and the fall of IBM in the PC world. This is the part of computer history, in my opinion, where Microsoft is most of the time on the good side and where it turns into the bad guy when it leaves MS-DOS to continue on with Windows. DOS history starts in the 70s when Intel got the 8086 processor out. It was the first 16 bit processor ever. The processor needed an operating system to run on and the only one available was CP/M 80 from Digital that ran on 8bit 8080 and Zilog Z-80 processors. Digital was supposed to created a CP/M version from the 8086 but nothing happened until april 1980 when a guy named Jim Paterson created an OS for the 8086 : QDOS or Quick and Dirty Operating System. This OS was rename 86-DOS afterwards and is the ancestor of MS-DOS. The task was hard for Patterson since he needed to preserve compatibility with CP/M 80 for its wide variety of programs. 86-DOS became a kind of enhanced version of CP/M in which some weak spots were reinforced. IBM was looking to build a 16 bit computer and found Microsoft a company to build its new OS. Microsoft received a prototype of the new computer, bought Patterson's Operating systems and went on. Patterson was supposedly still in relation with the project but it turned out he was held away most of the time. MS-DOS 1.0 appeared in august 1981. Version 1.1 followed in march 1982 and supported double-face 360k disks. While version 1.x of MS-DOS proposed some modifications to the original CP/M, it was close enough to allow program transfers without many problems. But CP/M was getting old and Microsoft wanted to improve the OS and to get away from the concepts of CP/M. This got a bit further with the release of version 2.0. The main improvement was the use of directories on the hard disk, a concept borrowed from UNIX. File-control blocks became also available as well as support for device drivers. Three 2.x sub-releases appeared in the same year to correct certain bugs. Version 2.01 offered support for international caracter sets including the Kanji set. The other two were versions 2.11 and 2.25 and were made of bug fixes. Version 3.0 offered many improvements over the previous versions. with the release of the PC-AT form IBM and was released in august supported 20Mb hard disks, 1.2Mb floppies and had faster internal months went by before sub-release 3.1 appeared to public. DOS now network use.

It appeared 1984. It now routines. Six supported

Two major version of DOS appeared right after. Version 3.2, released in december 1985, supported 720k 3.5in floppies. Release 3.3 offered better use of caracter set through page codes and now supported the 1.44Mb floppies we still use today. Problems started for Microsoft when it released ver 4.0 in august 1988. Microsoft had started to work with IBM on the OS/2 operating system some time before and it appeared publicly in spring 1988. This meant the DOS would not have a multi-tasking future. Altough it offered many new features, it was crippled with bugs. Version 4.01 did nothing to convince users of its leap in technology and most of the have got back to 3.3. I have noticed that since then, few 4.0 software versions have been released by Microsoft, the last one been NT 4.0. Go check out for DirectX 4.0, Windows 4.0 (renamed 95!) : Did Microsoft

make a superstition out of 4.0 releases ?. Anyway DOS 4.0 still offered many new things. The DosShell appeared as well as 2Gb hard disk support (which was limited to 32Mb before) and EMS to access up to 8Mb of RAM (instead of 640Kb). Still, bugs were numerous on this version and Microsoft had started its quest for Windows through OS/2. People mostly waited for version 5.0 to be released to get rid of 3.3. RAM handling was improved and allows memory resident programs to load in memory past the 640k barrier. This was the first version to be publicly beta tested by over 7000 users around the world. It had all the new features of 4.0 without the bugs and became a major version of the operating system after its release in june 1991. There were no sub-releases that I know of for version 5.0. Microsoft started to use court space when ver 6.0 was released. It had the new DoubleSpace software and was sued by Stac because of it. Stac was producing a disk compression software called Stacker that was available after version 5.0 was released. Microsoft was found guilty of code theft and was condemned to release a new disk compression software (DriveSpace). One funny thing funny is that it has no differences, either internaly or on the interface, with its bug fixed predecessor in version 6.20. It was released with version 6.22 in 1994. Many DOS versions appeared from different companies. The two major ones were MS-DOS and PC-DOS but Digital also had its own version, called DR-DOS. Digital also offered a GUI called GEM that was left in the shadow by Windows and both DR-DOS and GEM have known poor succes. Digital first released DR-DOS in 1981, maybe because they knew that they should have taken IBM's offer more seriously and lost a big battle there.