From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Smirl Subject: Re: Reading the EDID block for x86 machines Date: Wed, 12 Mar 2003 15:47:58 -0800 (PST) Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <20030312234758.82969.qmail@web14902.mail.yahoo.com> References: <1047508652.1005.6.camel@localhost.localdomain> Mime-Version: 1.0 Return-path: Received: from web14902.mail.yahoo.com ([216.136.225.54]) by sc8-sf-list1.sourceforge.net with smtp (Exim 3.31-VA-mm2 #1 (Debian)) id 18tFx0-0002Za-00 for ; Wed, 12 Mar 2003 15:47:58 -0800 In-Reply-To: <1047508652.1005.6.camel@localhost.localdomain> Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Antonino Daplas Cc: Linux Fbdev development list The system BIOS may not map the ROM into the first 1MB to copy it. It probably maps it to a high address and then plays with the X86 memory management to map a segment register to it. I am having vague recollections about doing this long ago when I worked at MS. I seem to recall there is a real mode instruction that will force a register like ES to point to a high mode address. This is how an ancient EMM driver (remember the AboveBoard and Lotus 123?) was implemented on a 386 without special hardware. So you would map the ROM to a high address, map the segment register to it, copy to C000, restore segment register and jump to C000:3. ===== Jon Smirl jonsmirl@yahoo.com __________________________________________________ Do you Yahoo!? Yahoo! Web Hosting - establish your business online http://webhosting.yahoo.com ------------------------------------------------------- This SF.net email is sponsored by:Crypto Challenge is now open! Get cracking and register here for some mind boggling fun and the chance of winning an Apple iPod: http://ads.sourceforge.net/cgi-bin/redirect.pl?thaw0031en