[TUHS] Interesting post about Microsoft and UNIX

[Arrigo Triulzi via TUHS]

> On 7 Dec 2024, at 13:34, Henry Bent <henry.r.bent at gmail.com> wrote:
> 
> Also interesting; I wonder if the "capability to run multiple MS-DOS applications under Unix" was shipped in a functional form, and what relation it might or might not have had to what was running on the AT&T hardware.

I used to run an 80286 “Taiwan clone” (as we called them in Italy) with Xenix 286 and, later, its 386 version which was SCO by then (memory a bit fuzzy on when Xenix became SCO Xenix and the Unix) and I definitely could run MS-DOS programs on the 386 - you would use the dos command which mapped drives either to physical drives (i.e. A: was the floppy) or directories within the filesystem. 

It was often used for businesses which had their inventory on MS-DOS bespoke software but wanted to “multitask” so we had some very dirty code which would run the DOS program on the serial terminals writing to a “network” drive which was actually a directory in the Unix filesystem.

In the meantime I was busy writing a migration layer which would allow us to compile the MS-DOS C code on Unix natively replacing, for example, code writing the pretty box characters on MS-DOS with curses equivalents. Fortunately the DB stuff was all
C-ISAM for which a portable library existed.

All of this was strictly with licenses found off the back of a truck, of course. Licensing bypass in Italy was a national sport.

(this was all done using the VM86 extension which, incidentally, still exists in Intel chips… this opens a whole other story about forgotten Intel extensions lingering in 2024 cores which can be used nefariously). 

Arrigo