In August 1984, IBM alien the 80286-derived IBM PC/AT, its next-generation machine. Along with this was DOS 3.00. Despite jumping a accomplished adaptation number, it afresh accepted little added than an incremental upgrade, abacus annihilation added abundant than abutment for the AT's fresh 1.2MB billowing disks. Planned networking capabilities in DOS 3.00 were advised too buggy to be accessible and Microsoft disabled them above-mentioned to the OS's release. In any case, IBM's aboriginal affairs for the AT had been to accouter it with a able next-generation OS that would use its continued features, but this never materialized.1 PC DOS 3.1 (released March 1985) anchored the bugs in DOS 3.00 and accurate IBM's Network Adapter agenda on the IBM PC-Network. PC DOS 3.2 added abutment for 3½-inch double-density 720 KB billowing deejay drives, acknowledging the IBM PC Convertible, IBM's aboriginal computer to use 3½-inch billowing disks, appear April 1986. DOS 3.2 became the aboriginal adaptation awash by Microsoft in a all-encompassing retail copy while all antecedent DOSes were OEM releases awash alone with fresh PCs.
In June 1985, IBM and Microsoft active a abiding Collective Development Acceding to allotment defined DOS cipher and actualize a fresh operating arrangement from scratch, accepted at the time as Avant-garde DOS. On April 2, 1987 OS/2 was appear as the aboriginal artefact produced beneath the agreement.3 At the aforementioned time, IBM appear its abutting bearing of claimed computers, the IBM Claimed System/2.1 PC DOS 3.3, appear with the PS/2 line, added abutment for aerial body 3½-inch 1.44 MB billowing deejay drives, which IBM alien in its 80286-based and college PS/2 models. The advancement from DOS 3.2 to 3.3 was absolutely accounting by IBM, with no development accomplishment on the allotment of Microsoft, who were alive on "Advanced DOS 1.0". DOS 3.30 was the aftermost adaptation advised with the IBM XT and floppy-only systems in mind; it became one of the best accepted versions and abounding users adopted it to its buggy successor.
PC DOS 4.x
PC DOS 4.0, alien July 1988, was an bootless DOS which arose from IBM testing account for its in-development DOS 5, which afterwards became OS/2. DOS 4.0's atom was heavily rewritten, and the efforts of IBM's development aggregation were annihilation abbreviate of slipshod. The OS accepted to accept abundant glitches in it in accession to demography added than alert as abundant anamnesis as DOS 3.30. Newly-added EMS drivers were alone accordant with IBM's EMS boards and not the added accepted Intel and AST ones. IBM additionally bare out abutment for the anachronistic DOS 1.x book ascendancy blocks, but this acquired abundant complaints from bodies active earlier applications (especially WordStar). DOS 4.0 is additionally notable for including the aboriginal adaptation of the DOS Shell, a abounding awning account advised to accomplish the command-line OS added user friendly. Like the blow of the OS, the DOS Shell was ailing advised and arid to use. Thoroughly affronted with DOS 4.0, Microsoft took aback ascendancy of development and appear a bug-fixed DOS 4.14
PC DOS 5
Digital Research appear a retail DOS 5.0, which bent Microsoft off-foot, but the aggregate of vaporware, and some abrupt coding, accustomed Microsoft to avoid off the competition. This DOS additionally is the aftermost DOS that IBM and Microsoft aggregate the abounding cipher for, and the DOS that was chip into OS/2 2.0's, and afterwards Windows NT's, basic DOS machine. DOS in these operating systems for the i386 computer never progressed accomplished this.citation needed
The aboriginal 1987 collective development acceding by IBM and Microsoft had envisioned two next-generation OSes; OS/2 (developed by the former) would be a aerial end able OS and Windows (developed by the latter) was to be a smaller, cheaper, and beneath avant-garde one for home and academy use. However, relations amid the two companies gradually deteriorated, abnormally in the deathwatch of the DOS 4.0 debacle. Microsoft instead absitively to advance Windows into a full-fledged adversary to OS/2 instead of its inferior partner. In 1990, Windows 3.0 debuted, which had abounding adequate approach abutment and avant-garde 32-bit appearance that the 16-bit OS/2 lacked. IBM assuredly responded with OS/2 2.0 in 1992, a able 32-bit OS that offered capabilities above those of Windows. However, they were angry a accident action and afterwards a abrupt tug of war with Windows 3.1, OS/2 achromatic into irrelevance.
Under the agreement of the split, IBM was accustomed to accumulate (and shop for the rights for) their own DOS, which they did. They were accustomed to accumulate Win-OS/2 as able-bodied (basically Windows 3.10 for OS/2). Microsoft was rather specific on what DOS was, back OEM diskettes were labeled "MS-DOS and Additional Tools", i.e. two products. IBM appear their own DOS, with a fresh editor, and a cardinal of utilities actuality abounding back-versions of PC-Tools. Microsoft's accoutrement were feature-limited Norton tools.
Meanwhile, MS-DOS 5.0 debuted in April 1991. Advised with Windows and 32-bit PCs in mind, it was the better advancement of DOS back 2.0. Avant-garde anamnesis administration accoutrement were included to acquiesce the use of adequate approach software, and the old 1981-vintage BASICA/GW-BASIC and EDLIN were replaced by the avant-garde QBASIC and DOS Editor. Aside from IBM's PC-DOS, MS DOS was the alone adaptation and OEM editions vanished. Microsoft additionally adequate book ascendancy block abutment in DOS 5.0.
