MS-DOS
MS-DOS was made popular by Microsoft for not only being the bundled operating system on the IBM-PC but also being available to the other clone OEM's of the time.
Microsoft had sold IBM on the idea of MS-DOS when talks for CP/M had broken down. At the time Microsoft had no such product but was able to secure the rights to "86-DOS", a CP/M clone written by Tim Paterson, for the sum of $50,000. This has been the best ROI ever, as MS-DOS has made Microsoft untold billions of dollars.
MS-DOS uses the Int21 interface to allow programs to communicate with MS-DOS. It is designed to be a single tasking OS, that runs on the 8088/8086 CPU, and on the real mode of the 80286 and higher CPU's. There are ways to crudely multi-task via TSR's and other shells that hook the clock interrupt and jump execution, although these are usually unstable at best.
DOS made use of the FAT file system, and thus its popularity.
The OEM for IBM is called PC-DOS and version 6.xx of PC-DOS is quite different than MS-DOS 6.xx with the development of it being done completely by IBM.
Contents
Versions
MS-DOS 1.25
This was the first version of MS-DOS to be released to OEMs other than IBM with similar functionality. Some of the OEMs included Zenith, Eagle Computer, TI, and Sanyo.
MS-DOS 2.00, 2.10, and 2.11
This version supported 10 MB hard drives and on some systems such as the TRS-80 Tandy 2000 and Toshiba T1100 Plus supported non-standard disk formats such as Quad-Density and 3 and a half inches floppy disks. OEMs included DEC Rainbow, Tandy, AT&T, and Wang.
MS-DOS 3.0
This version supports up to 32 MB hard drive partitions and 1.2 MB high-density floppy drives. There we very few OEMs for this version including Apricot and Compaq.
MS-DOS 3.1
Added support for the NET command, and the Network re-director support both for server and client. It became the minimal DOS version for any network based software.It had many OEMs including Compaq, Wyse, and Zenith.
MS-DOS 3.2 and 3.21
Released April (or, according to some, August), 1986. This was the first OEM version of MS-DOS, a generic version for IBM-compatible PCs which for the first time included MS-written versions of the IBM utilities found in PC-DOS.
Earlier versions of MS-DOS could not be considered complete, they only included the core parts (i.e. the MS-developed parts of PC-DOS), were licensed to non-IBM vendors, and had to be augmented with modifications as/if needed for the particular hardware and with vendor-written versions of utilities found in PC-DOS. Documentation also had to be provided by said vendors.
MS-DOS version 3.2 changed all this, but the reason a generic MS-DOS could be produced was that vendors had started to see the point of being truly IBM compatible.
There were also a few non-generic OEMs including Tandy, Zenith, and Wang. One of the major additions to this was 720k 3 and a half inch floppies.
MS-DOS 3.21 was minor revision with quite a few OEMs.
MS-DOS 3.3
This was the first retail version of MS-DOS. This release added support for the 3 1/2" high density floppy. I also recall this version being VERY popular... Even to the point where people avoided MS-DOS 4.00 to run this version. It added extended partition and logical drives. MS-DOS 3.3 also included some support for the FAT16 filesystem, however its format command still was limited to FAT12 filesystems. IBM (after a joint development agreement with Microsoft) was the main developer of MS-DOS 3.3, and PC-DOS 3.3 was nearly identical to the OEM version of MS-DOS 3.3.
MS-DOS 3.31
MS-DOS 3.31 was a Compaq only OEM. It was identical to MS-DOS 3.3 except you could create partitions up to 512 MB.
MS-DOS 4.0
MS-DOS 4.0 could use partitions larger than 32MB. I've seen it on 512MB disks, it may go up to the full limitation of FAT16 of 2GB. DOS 4 still included the ancient programs edlin(MS-DOS and PC-DOS) & gwbasic(MS-DOS).
The first release 4.00 was VERY buggy, resulting in random disk file corruption, although I recall something about 'large' 32MB files and various other things. Most people downgraded to 3.30. 4.01 addressed whatever issue it was, and it was good news. The update 4.01 was released less than 3 weeks after 4.00, but the damage was done.
Also making its appearance in MS-DOS 4.0 was the DOS shell, a simple GUI, to help people navigate their systems, Which was orginally a program called DOS MANAGER 1.0,
MS-DOS 4.0 was, as for version 3.3, mainly developed by IBM.
4.0 would have been released in October, 1988.
MS-DOS 4.00M
Also known as Multitasking DOS, or European DOS , this is the oddball outcast, rather it is a re-write of MS-DOS 2.1 to facilitate multitasking. It adds support for NE style executables, a task switcher, along with a few utilities to monitor the system. Also included is the needed LINK4 NE linker for the OS. So far no SDK or any real documentation has been found, although it is possible to build simple programs with Microsoft C 3.00 and link them with LINK4. MS-DOS 4.00M served as the foundation to what was to become OS/2.
It was the first version of MS dos, that its external commands were written entirely in 'C.'
There is one known disk set from ICL for this release, although it doesn't have a proper official place in the release tree, but it's name does place it here. The files are dated 11-26-85. The ICL disks are 1.2MB HD disk, and consist of MS-DOS 4.1, ICL applications, and two disks of Windows 1.0.3. No online copies exist.
The other disk set(WinWorld), from Sharp/WinWorld is from a Seimens Computer's 4Mb ROMS that had a bootable copy, but no disk drive, it does not contain the swapper. MS DOS 4.0M
The third disks set that JS located, boots the same way, but includes the swapper. MS-DOS 4.0M
MS-DOS 5.0
This release was significant to allow for FAT partitions larger then 32MB, going up to 2GB. Also big features were himem.sys which allowed MS-DOS to execute in the top 64KB of protected mode because of a hardware bug in the IBM AT's handling of extended memory. Emm386.sys also was made popular allowing 386's to simulate EMS memory with extended memory, and loading device drivers & TSR's into the reserved hardware space.
Version 5.0 also brought Qbasic 1.0, to replace the aging GWBasic. Included were the example programs money, gorilla, nibbles & remline. Along with a proper editor based on the Qbasic interface, supplementing the ancient edlin.
DOS-5 also used an install program with the same look & feel from Windows 3.0.
There is also a horrible promotion video on youtube.
With version 5.0 Microsoft was again the main developer of MS-DOS.
MS-DOS 6.0
This release added disk compression in order to compete with Stacker. Also included were some simple tools licensed from Central Point, including an anti virus program MSAV, a graphical backup program MSBACKUP, and a defrag program licensed from Symantec.
MS-DOS 6.0 was mainly to compete with the feature full DR-DOS 6.0
MS-DOS 6.20
This release fixed bugs in the compression software and replaced CHKDSK with SCANDISK which is still used today.
MS-DOS 6.21
This release is simply 6.20 minus the compression software due to a lawsuit from Stacker.
MS-DOS 6.22
This release was to rectify the various lawsuits around the bundled disk compression by coming up with a unique compression software called drvspace. It should also be noted that drvspace was also the compression software used in Windows 95, 98, and ME.
This was also the last retail version of MS-DOS. As version 7 of MS-DOS was the base part of Windows 95.
