*BSD News Article 30056


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From: hamish@zot.apana.org.au (Hamish Coleman)
Newsgroups: comp.os.386bsd.misc,comp.os.linux.misc
Subject: Re: Impressions: FreeBSD vs Linux
Date: 5 May 1994 22:55:19 +1000
Organization: WFLGA (Worlds First Linear Gerbil Accelerator :)
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In <2pk3in$nor@acme.gatech.edu> gt8134b@prism.gatech.edu (Robert Sanders) writes:

>othman@oasys.pc.my (Othman Ahmad) writes:
>>terry@cs.weber.edu (Terry Lambert) writes:
>>> Actually, a better plan is a protected mode vm86() call so anything
>>> anyone wants to write in kernel space could make a BIOS call if it
>>> needed one.
>>This may be called biosemu.
>>Implementing this should be easier than dosemu.

>Er, well, maybe.  The VGA BIOS doesn't run in a vacuum: I know of at
>least two that use the PIT and PIC chips (interval timer and interrupt
>controllers).  That's not trivial to implement correctly.  These
>BIOSes also assume the standard memory map.

Hmmm - -  Just came in on this one, but I have written such a 'biosemu'
program some time ago, just to see if it was possible.

If you have Linux, and want to have a look, it is included as part of
a program called virtdos, and is called 'readm' itself.

tsx-11.mit.edu:/pub/linux/ALPHA/dosemu/virt_dos0.04.tar.gz

using this program, I could successfully change video modes on my et4000
and my trident 8800.  It doesnt emulate anything besides 1M of ram and a
braindead vert/horiz retrace CRTC status register.  Also, it dumps out a
list of the IO instructions and their results.


-- 
Use Linux!                                         hamish@zot.apana.org.au
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