mmue@ethz.UUCP (Markus Mueller) (08/03/87)
I tried to get MINIX running on an OLIVETTI M19, and to my surprise it
sees to boot correctly. However quite a few things do not work the way
they should.
First what is working:
- The system boots up correctly. You can log-in, do work, ...
- The floppies work correctly. I have no problem reading from or
writing onto them although the drive does a lot of recalibrations
during write. The startup delay time problem known from the OLIVETTI
M24 did not occur.
Now what is not working:
- The display does not scroll, and the cursor does not work either (remains
at the beginning of the line following the one you pressed '='). When
you write onto the screen, the writing position will eventually go off
the screen, but will return back to the top of the screen at some odd
position after you have written out about 80 more lines. This wraparound
allows some limited work with the system, including recompiling the kernel
and rebuilding the system (and all this on a system with only one drive
and no hard disk :-).
- The printer port does not work
- The hard disk does not work at all. The access light won't even flash
on an attempted access. However I have not yet tested the various
fixes that appeared on the net.
Now for what I need your help: the scrolling problem seems to be a really
serious one. I checked things out and fount that MINIX is correctly
detecting the presence of a CGA, and correctly sends the commands for scrolling
and cursor control to the 6845 controller, BUT THE 6845 CONTROLLER JUST WON'T
LISTEN!!!!! Of course I then tried to play around with the 6845 from MSDOS,
and I found that writing to the 6845 usually worked, sometimes failed, and
occasionally either locked up the entire system (bus conflict?) or kicked
the processor into INT 0. Other people seem to have problems too; some cannot
even boot MINIX because it immediately crashes with 'unexpected int < 16'.
Therefore my question: What is the secret of the 6845 crt controller in the
OLIVETTI M19? How do I program it correctly?
Please mail; I will post a summary.
Markus Mueller
Institut fuer Informatik
ETH Zurich
Switzerland
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