DOS emulation on old UNIX systems
=================================

I briefly noticed somewhere (I  think it was on the RetroComputingForum
[1]) information about  a very small ISP implementation  which run even
on the 8086 systems (among others) [2].

I have never  became understand the LISP but it  is probably the reason
why this  language is  still interesting  for me. I  have an  old 80186
laptop which (the PSION MC600) which  I use for various strange things.
And  trying/learning of  a very  simple LIPS  may fit  here. SO  I have
started to browse the klisp's author pages [3].

A lot  of interesting stuff is  here! Some books, come  crazy compilers
(an another very tiny C89 [4] compiler,  too) but what I have found the
most interesting was the x80/DOS computer emulator [5]. There are a lot
of such things everywhere (the DOSEMU, the DOSbox,...) but this one was
interesting because a) it is very small, b) it runs (by default) on old
SGIs, Suns and HP workstations!

It is somewhat  limited, too (it seems that it  was originally a school
project of it main author): an  8086 emulation only, text mode only and
so on. But this is probably the reason why it is fast.

So I have downloaded the thing [6], modified the Makefile to fit my SGI
machine  (the Makefile  is well  documented)  and the  have stared  the
compilation. The only  needed fixes were adding of  the -L/usr/lib32 to
the Makefile and commenting out of  one of curese functions which seems
not to be available in IRIX implementation of the curses library.

The emulator  does require a disk  image with a compatible  DOS system.
The official Microsof OSes are supported as are some others but not the
FreeDOS. But a 8086-only version of the FreeDOS exists [6] and while it
looks like no longer developed one, it works well here.

So  I have  got the  1.44MB disk  image form  the sf.net,  added a  few
programs (under the Linux) and started to play with the emulator. It is
fast, it runs the  Volkov Commander and the Vim 5.x  very well (but the
PSION Organiser 2 emulator crashes the whole thing immediately). I have
a little  success in making and  mounting of a HDD  disk image, though.
Maybe later.

In any case,  this thing is much  faster than the DOSbox on the SGI O2.
And  the DOSbox  does not  compile on  older IRIXes.  SO the  next step
should be compilation on my old good SGI Indigo with the IRIX 5.3...


P.S. And  how about vi-like  text editor for the  CP/M? It can  be also
found there...


Written on the SGI O2.


References:

[1] https://retrocomputingforum.com
[2] http://t3x.org/klisp/index.html
[3] http://t3x.org
[4] http://t3x.org/subc/index.html
[5] http://t3x.org/DOS/index.html
[6] https://svarog86.sorceforge.net