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Article #6480Re: IBM PC/AT Memory Map
From: bill
Date: Thu, 08 May 1986 17:29
Date: Thu, 08 May 1986 17:29
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1494 bytes
The 64K at segment E000 is reserved for motherboard BIOS extension ROMs. Even though the ROM sockets on your board are empty, I'd expect that any attempt to read from them would still enable the 74ALS245 buffers that isolate the ROM sockets from the system bus; these buffers will hard drive the bus to some "unknown" state during a read (because of their floating inputs). You might try moving your card to somewhere in the C800-E000 range. This is the address range reserved for plug-in adapter BIOS extension ROMs. (Your EGA card lives at the 16K starting at segment C000). Just make sure the block you pick doesn't conflict with any of your other plug-in cards. Also, it may be necessary to add a wait state. You might also get hold of an AT Technical Reference Manual, if you don't already have one. Bill Frolik hp-pcd!bill
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: notesfiles - hp 1.2 08/01/83; site hp-pcd.UUCP Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!burl!ulysses!ucbvax!hplabs!hp-pcd!bill From: bill@hp-pcd.UUCP (bill) Newsgroups: net.micro.pc Subject: Re: IBM PC/AT Memory Map Message-ID: <15200021@hpcvlo.UUCP> Date: Thu, 8-May-86 13:29:00 EDT Article-I.D.: hpcvlo.15200021 Posted: Thu May 8 13:29:00 1986 Date-Received: Tue, 13-May-86 00:38:16 EDT References: <697@wjvax.UUCP> Organization: Hewlett-Packard - Corvallis, OR Lines: 19 Nf-ID: #R:wjvax:-69700:hpcvlo:15200021:000:834 Nf-From: hpcvlo!bill May 8 09:29:00 1986