The industry-recognized fact that the MS-DOS 4.0 operating system had serious stability issues is well-established. This version of the system was notorious for its numerous faults. Even popular software like WordPerfect 5.1, Lotus 1-2-3, and the classic game Doom frequently crashed on this system, foreshadowing the deep frustration encountered by computer users, which predated the infamous blue screen of death issue of the Windows operating system.
MS-DOS 4.0 was widely criticized for requiring up to 92KB of massive memory. Although Microsoft has stated that interested users could try installing MS-DOS 4.0 on the original IBM PC XT and newer Pentium computers, it can also be experienced running on open-source emulators such as PCem and 86box.
It is worth mentioning that Microsoft released the source code for MS-DOS versions 1.25 and 2.0 through the Computer History Museum in 2014. In addition, Microsoft also open-sourced Word (for Windows 1.1a version), GW-BASIC (first released in 1983), and the Windows File Manager (originally aimed at Windows 3.0 and released in the early 1990s). Among them, the Windows File Manager has been actively maintained and received the latest cumulative update in March 2024.
The MS-DOS operating system was developed and improved by developer Tim Paterson based on QDOS (Quick and Dirty Operating System), ultimately becoming the operating system for IBM personal computers. Since its first release on the IBM PC in July 1981, MS-DOS remained one of the most widely used operating systems until 1990.
The release of this source code allows programming enthusiasts and computer historians to delve deeply into the study and understanding of the design and evolution of the operating systems of the time.
