When talking about the “DOS” operating system, many friends born in the 90s and 00s might not have experienced it, or have only seen it in textbooks. However, for those born in the 70s and 80s, the impression is very profound.

In the 386 and 486 eras of the 1990s, “computers” were not called “computers”; they had another more colloquial and common name, “microcomputer”. They were very expensive, only equipped by schools, companies, and institutions, and most individual households could not afford them. Moreover, they only had local area networks, not the internet.
Back then, most friends born in the ’70s and ’80s first encountered microcomputers in school computer labs, where at most they had three or four computer classes per week. Sometimes, the classes were purely theoretical without practical computer use. Even when there was a chance to use the computers, it might require two or three friends to share one microcomputer due to limited availability.
The computer screens back then were all black, and there were no mice; everything was operated by typing commands on a keyboard, and this was the DOS system. Teachers and textbooks explained various DOS commands and some commands that left a deep impression were “dir”, “delete”, etc.
I remember that the computers in the computer room were installed with DOS version 5.X, and I still clearly remember the teacher telling us that “the latest version of DOS is 6.22.”
So, why am I bringing up these things today? The main purpose is not nostalgia, but rather a recent significant event closely related to these topics.
On April 25th, Microsoft officially open-sourced and released the source code (Via Github) of the MS-DOS 4.00 operating system, including related binary files, disk images, and PDF documents (see image above), allowing third-party developers to freely modify and use it.
This system was not solely developed by Microsoft; it was a joint development with IBM, written using 8086 assembly code, and has a history of 45 years.
Although Microsoft has released the source code for MS-DOS 4.00, how third-party enthusiasts can utilize this code is a tricky issue.
To this end, Microsoft advises learners that finding old computers from that era would be ideal for local installation and experience. If that’s too troublesome, or if you don’t have the conditions, you can also run it in open-source emulators like PCem and 86box.
In Microsoft’s announcement, the company expressed gratitude to the original creators of these codes, some of whom are still working at Microsoft and IBM, and thanked those who cared for, helped collect, and organize these codes.
Additionally, it should be noted that this is not the first time Microsoft has released the source code for the MS-DOS operating system. In 2014, Microsoft released the earlier MS-DOS 1.25 and MS-DOS 2.0 source codes, which were later supplemented and optimized, and this time they were re-uploaded and released together.
Most non-professional enthusiasts born in the ’70s and ’80s, may not have the time, energy, conditions, or necessary foundational knowledge to review and deploy these codes. It is recommended to revisit the experience of the DOS operating system using VirtualBox on a virtual machine, as these are the fleeting moments of our youth.
Related:
Disclaimer: This article is created by the original author. The content of the article represents their personal opinions. Our reposting is for sharing and discussion purposes only and does not imply our endorsement or agreement. If you have any objections, please contact us through the provided channels.