X-Authentication-Warning: delorie.com: mail set sender to opendos-bounces using -f From: shadow AT shadowgard DOT com Organization: Shadowgard To: opendos AT delorie DOT com Date: Thu, 05 Aug 2004 23:26:03 -0700 MIME-Version: 1.0 Subject: Re: 7C00h Trivia (fwd) Message-ID: <4112C20B.12635.24A92CF@localhost> In-reply-to: X-mailer: Pegasus Mail for Windows (4.21b) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body Reply-To: opendos AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: opendos AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On 5 Aug 2004 at 22:12, Norman C. Leet wrote: > Does anyone know the history of how 7C00h came to be the > particular address where int 19h loads the disk boot sector to > to memory? I wouldn't be surprised to find that it goes bsack to the early days of CP/M. CP/M 1.x would run on a system with only *8k* of RAM. Later versions required more RAM. I note that 7C00h is 1024 bytes before the end of the first 32k of RAM. That gives you room to load two MS-DOS sectors at the "top" of RAM on a 32k system (which was probably the minimum that DOS required way back when) -- Leonard Erickson (aka shadow) shadow at shadowgard dot com