Holy cow, this is huge! DOS 1.x and 2.x are too old to run a lot of vintage DOS software, but 4.x would run just about everything.
Those are very different operating systems, this is DOS 3.2 + later abandoned very crude multitasking features. Roughly.
And this matters because DOS 3.3 was a milestone.
4.01 comes from 4.00 which has nothing to do with 4.0 (yay for versions).
Microsofts' releases have the benefit of being unambiguous.
"Caldera grants you a non-exclusive license to use the Software in source or binary form free of charge if your use of the Software is for the purpose of evaluating whether to purchase an ongoing license to the Software. The evaluation period for use by or on behalf of a commercial entity is limited to 90 days; evaluation use by others is not subject to this 90 day limit but is still limited to a reasonable period"
DOS 3.3 couldn't understand large partitions -except for Compaq dos 3.31. But regular dos 3.3 couldn't. I don't think dos 3.2 could even understand extended partitions/logical drives -much less large disks.
Still -pretty neat!
This is not accurate. Several OEMs added proprietary variations of FAT which supported larger partitions. For instance I run Zenith MS-DOS 3.30+ which has this ability on a Zenith Z-161 XT compatible luggable.
Compaq’s 3.31 added FAT16B support which allowed larger partitions and was the standard for larger partition support going forward in standard MS-DOS.
An interesting thing about DOS is the OS wasn't very involved. Programs did a lot of things we now think of as the realm of an OS, like talking directly to I/O addresses or installing interrupt handlers. I feel like a DOS implementation doesn't even need to do a lot of things, maybe part of why DOS4 is "good enough".
DoubleSpace/DriveSpace?
Mostly, you are absolutely right, yes. MS-DOS 5.0 was the peak, and then it started to acquire bloat as MS bundled stuff to compete with DR-DOS 6 and DR-DOS 7.
But the thing is that by modern standards, the bloat is tiny. :-)
I gave MS Office 97 a bad review at the time because it was several times bigger than Office 95, had virtually no new functionality, but introduced a pointless new file format just to get people to upgrade so they could read the files sent to them by companies with the newer version.
But for a decade now, Word 97 is my go-to version. With all the service releases installed, it works great, it's tiny by modern standards -- I think a full install of Word with all the optional filters and things totals 14MB -- and it's lightning fast on 21st century hardware.
Word 95 is even smaller and quicker, but it can't read or write the file format that everyone else, from Pages to Wordpad, uses. So it's crippled: everything has to go through LibreOffice first, to convert it to a .DOC format anything else can view, import, edit, or print.
Time changes the meaning of bloat somewhat.
It's also amazing how long things like DOC to DOCX took to really "take hold" in the industry at large. I still get DOC files now and then.
The latter one is more capable and compatible with modern things. Open Word and see how it calls DOC "Word 97-2004"
There have been at least 3 successive MS Word file formats:
Word for DOS, WinWord 1/2/6/95: old .DOC format
(I think this also applies to Classic MacOS Word 1-5.)
Word 97, 2000, XP, 2003: new .DOC format
(Classic MacOS Word 98, X and 2001 were based on a port of the Windows codebase. Mac OS X Word 2004 and later are OS X-only, but are still based on the Windows codebase and use the same file formats.)
Word 2007-365: new Zipped XML format, .DOCX
I don't understand if this source can be usefully integrated into modern DOS preservation projects.
The problems came from limitations of the BIOS interface (especially size)
Only for drives, but still...
For the actual hardware or PCem, FreeDOS exists and is alive. DR-DOS has also been open sourced.
Bryan Sparks did open-source CP/M a little while back, but AFAIK he hasn't said anything about DR-DOS so far.
Fortunately for the commons, what's done is done.
The license file inside the original Caldera OpenDOS 7.01 source archive says:
"Caldera grants you a non-exclusive license to use the Software in source or binary form free of charge if (a) you are a student, faculty member or staff member of an educational institution (K-12, junior college, college or library), a staff member of a religious organization, or an employee of an organization which meets Caldera's criteria for a charitable non-profit organization; or (b) your use of the Software is for the purpose of evaluating whether to purchase an ongoing license to the Software. The evaluation period for use by or on behalf of a commercial entity is limited to 90 days; evaluation use by others is not subject to this 90 day limit but is still limited to a reasonable period."
So that website is incorrect when it says OpenDOS was released under an open-source license. Not surprising though - most websites discussing OpenDOS make this error. Possibly because at the time I believe Caldera did actually talk about open-sourcing DR-DOS, they just failed to to actually follow through.
If he still has the source code, whats needed is for Bryan Sparks to release it under some regular open-source license like Microsoft have done here.
To the point I might have dreamed it. Odd.