Microsoft opened MS-DOS 4.0 code on GitHub - it turned out to be broken due to UTF-8 and timestamps

In April, Microsoft published the source code of its MS-DOS 4 operating system from 1986 on GitHub. This is not the first release of DOS code, but this one seems to break some critical files.

As noted by the well-known developer and author of the OS/2 Museum blog Michal Necasek in the article "How Not to Release Historic Source Code", the inability of git to save timestamps and the conversion to UTF-8 breaks almost everything. Necasek praised the release of the code, but criticized the errors that occurred in the process: "Please, do not distort historical source code by shoving it into (stupid) git."

Of the two problems, converting source files to UTF-8 is the biggest issue. Old systems cannot parse UTF-8 and probably cannot be updated for it either. The 512-byte string length limit in MASM MS-DOS 4 is exceeded by the conversion to UTF-8, making the strings unreadable.

The severity of the file errors varies, but the OS/2 Museum publication notes that the main system files perfectly match the original version 4.00, which fixed several errors. It was not directly available but was sent to computer manufacturers.

The original message recommended simply releasing the raw files in an archive without converting to UTF-8 or anything similar. However, the story continues immediately in the comments, where one of the MS-DOS 4 developers, Connor Hyde, also known as Starfrost, acknowledges the problem and reveals the legal reasons for not including timestamps.

The discussion between Michal and Starfrost continues in the comments, then they moved it to emails. Despite Michal's critical tone, it is noted that in the corporate policy, it is "obvious" that an indie developer like Starfrost is not to blame.

These problems will likely be resolved soon so that MS-DOS 4 can function as before. However, MS-DOS 4 was not very popular because it used a whopping 92 KB of RAM - a huge amount. Interestingly, this led to the competitor DR-DOS completely skipping versions 4.0-4.99 in favor of jumping from version 3.41 to version 5.0.

Source: Tom's Hardware