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Posted: **Wed Jan 06, 2021 8:45 am**

There was "MS-DOS 2.50" mentioned on Wikipedia, claimed to be an internal version from 1983. Was it even real? The last MS-DOS 2 version I know about is MS-DOS 2.25 from October 1985, which included foreign language support.

It is also mentioned here: https://www.msx.org/wiki/The_History_of_MSX-DOS.

Here’s what I can reconstruct about the history of MSX-DOS:

On August 10, 1983 I got a call from Paul Allen asking me to do a Z80 version of MS-DOS. I didn’t jump at the chance, as I was trying to get the first product for my startup Falcon Systems ready to go. I made a suggestion of one or two others I thought could do it and he said he’d already asked. He was in a hurry to get it done and nobody else could meet his timeline. But he was willing to pay cash and let my company distribute MS-DOS, so I decided it was a good deal. On August 17th I signed an agreement to do Z80 MS-DOS 1.25 for $100,000 and the right to distribute MS-DOS 2.0, 2.5, & 3.0 with a hardware product without royalty.

Posted: **Fri Jan 15, 2021 5:47 am**

I think 2.50 was a placeholder version. I've never seen it mentioned historically. There were tons of 2.12 variants made for various OEMs. Sometimes they took liberty with version numbers.

Posted: **Fri Jan 15, 2021 7:26 pm**

bitslasher wrote: ↑
Fri Jan 15, 2021 5:47 am
I think 2.50 was a placeholder version. I've never seen it mentioned historically. There were tons of 2.12 variants made for various OEMs. Sometimes they took liberty with version numbers.

I don't know if there's any proof of what MS-DOS 2.50 was supposed to be. However, at an early development stage, version 3.0 was supposed to be a multitasking DOS (later known as European MS-DOS 4), and the network redirector was supposed to be part of a later release of DOS 2.x. So maybe MS-DOS 2.50 was the development name of what became DOS 3.0.

Posted: **Sat Jan 16, 2021 6:13 am**

Has an employee from Microsoft from that time period ever come forward with any information about this kind of stuff?

It'd so cool to find someone that worked at Microsoft in that group from like 1981 until 1989, up until 5.0 was written.

I've seen where Tim Paterson shared a story about the work he did on MSX-DOS, but that was a fork or rewrite of MS-DOS 1.25 for the MSX system, much later in like 1985. By that time DOS 3.0 was out on normal PCs.

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MS-DOS 2.50?

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