[TUHS] Interesting post about Microsoft and UNIX

[Arrigo Triulzi via TUHS]

On 7 Dec 2024, at 18:01, Henry Bent <henry.r.bent at gmail.com> wrote:
> Sadly, that's the answer I was expecting - the locking didn't really work in practice.  That might go some way towards explaining why this concept of multiple DOS sessions under UNIX didn't really have widespread adoption.

I cannot honestly see how it could be made to work - locking, even in Unix, was very much a case of “let’s hope we all use the same function call” and, in the specific case of MS-DOS, was hardly necessary since it was a single-user OS running a single application at a time. The arrival of networking probably introduced locking to MS-DOS in the same way hopeful way.

There was no real expectation on our part that the DB would not be corrupted by multiple MS-DOS sessions writing to it, even if using C-ISAM, because the assumption would have always been “one machine, one user, one task”. Fortunately the port to Unix fixed this because C-ISAM was conscious of the concept of multiple accesses to the database.

> There were always all sorts of "DOS under UNIX" ideas, from these early concepts through all the way to Sun's physical PC boards, but none of them ever really seemed to gain significant traction.  The only connecting concept seems to be that DOS just wasn't meant to be a multi-user OS, and certainly not a networked one.

Even on the i286 there were attempts at having MS-DOS running within a multi-user OS. Remember that OS/2 on the 80286 used a triple fault to get you back into real mode to execute an MS-DOS program. 

"Running MS-DOS” was really important in those days and a lot of effort was expended trying to get that to work in some way[1]. 

Arrigo

[1] I am a (very) guilty party for flooring my CPUs and making fans sound like 747s by running Simcity 2000 and Railroad Tycoon in dosbox on Linux.