Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!amdcad!diablo!phil
From: phil@diablo.amd.com (Phil Ngai)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Protected mode and PC/XT cards
Message-ID: <25868@amdcad.AMD.COM>
Date: 5 Jun 89 22:49:27 GMT
References: <158322@neabbs.UUCP>
Sender: news@amdcad.AMD.COM
Reply-To: phil@diablo.AMD.COM (Phil Ngai)
Organization: Advanced Micro Devices, Inc. Sunnyvale CA
Lines: 13

In article <158322@neabbs.UUCP> alun@neabbs.UUCP (ALUN SAUNDERS) writes:
|Can anyone tell me what happens to memory on 8-bit PC/XT add-on cards
|installed in a 286 or 386 machine, say video RAM, when that machine is
|running in protected mode ?  Since the card is only seeing the bottom
|20 bits of the 24 address lines, won't the offending lump of memory

No, IBM recognized this possible compatibility problem and defined new
memory read and write lines on the second connector for access to the
16 megs. The old read and write lines only go active for the bottom
one meg. 
--
Phil Ngai, phil@diablo.amd.com		{uunet,decwrl,ucbvax}!amdcad!phil
"The government is not your mother."