Microsoft recently re-opened its oldest legacy, MS-DOS versions 1.25 and 2.0, to the public by putting it in the cloud on GitHub. The reason mostly is for ease of use and Microsoft has already stated its intent to keep the source files static.

Both versions of the popular personal Computer OS were released at the beginning of the 1980s, with MS-DOS receiving updates up to version 6.22 as retail version. The final version (8.0) was part of Windows ME and was released in 2000.

In the fast evolving world of commercial applications, on-going releases spanning over twenty years is significant and the Internet is filled with articles that refer to this product as a dinosaur. However, from the point of view of many of the legacy applications developed internally in banks, MS-DOS can still be considered a young child.

At Anubex, we regularly receive source code of mission critical business applications (with programs written in COBOL, Assembler, Natural, ...) that serve millions of business transactions each day. This source code typically contains comments that refer to the day they were first written: often showing dates going back to the 1970s and 1980s. Such sources typically also contain a revision history that contains dozens of version numbers with dates and a short specification of what was done for which purpose.

Aside from having a rich history, these applications often still are very mission critical, and still serve their business purposes well. In other words: they have not even completed their full life story. By using CodeTurn they can be transformed in, for example, Java or C# applications and easily get to serve our clients for another 10 or 20 years.

You can find MS-DOS on GitHub here!