Slightly OT: DOS programs in Win XP

From: Steve Thatcher <>
Date: Tue Jan 4 05:14:01 2005

win2K and on will not allow any hardware direct access to hardware. In the DOS days, programs "talked" directly to display cards to bypass BIOS or expected to load their own memory manager (that is the Phar Lap error you are receiving). There are a lot of console programs that will work just fine on XP as long as they access normal BIOS and DOS system calls. AutoCAD is not in that category...

best regards, Steve Thatcher

-----Original Message-----
From: Computer Collector Newsletter <>
Sent: Jan 3, 2005 11:58 PM
Subject: Slightly OT: DOS programs in Win XP

A while ago I asked if anyone on the list could help me get AutoCAD 12 for DOS.
 Several people came through and I now have a copy. Thanks, everyone!

As expected though, it doesn't work and play nicely with Windows XP. I was
hoping that just running it through a command prompt window and giving that
giving the Win 95 compatibility attribute to the acad.exe file would make it
work. It didn't and I got a strange error message:

"Phar Lap err 74: Can't use -REALBREAK under this version of DPMI"

So I Google that and found a few threads like this one:

Apparently it's just not possible to run Acad 12 in 'real' DOS in XP. I
already knew XP's prompt is nothing close to real DOS, but I was hoping to find
a way to trick the program, or a way to emulate DOS perhaps. Anyone have a
clever solution to this? (I do have a suitable second PC to install real DOS
on, but I'd rather not have to dedicate a whole system just to use one program.)
Received on Tue Jan 04 2005 - 05:14:01 GMT

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