Enhanced EGA's under VP/ix

[Rick Richardson]

First, let me say that, by and large, the vp/ix claims of DOS
under UNIX are true, and that I'm quite happy running DOS
programs under vp/ix.  The only real surprise I've run into
is that programs which tweak the timer interrupt hardware
(such as our 3-Demon video game) won't work correctly.  vp/ix
apparently refuses to simulate a faster timer interrupt. (DOS
uses 18.2 HZ, and 3-Demon changes it to around 60 HZ).  So, the
play action and music of 3-demon are slowed, since they are
synced up to the timer interrupt.

We ran into one problem, which I'd classify as an installation,
lack of documentation problem.  The extended modes of our EGA
adapter (A Paradise AutoSwitch EGA 480) wouldn't work under vp/ix.
It turns out that:

	/usr/vpix/defaults/romega

contains the image of some other EGA adapter ROM.  By simply
replacing the contents of this file with the contents of the
PEGA ROM, we were able to get the enhanced modes to work.

To make a copy of the ROM, the following command suffices:

	dd if=/dev/mem skip=1536 count=32 >romega

Plus, this gets rid of the 'funny' character set that we saw
with the default EGA ROM BIOS under vp/ix.
-- 
		Rick Richardson, PC Research, Inc.

(201) 542-3734 (voice, nights)   OR     (201) 389-8963 (voice, days)
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