Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!cca!johnl From: johnl@cca.UUCP Newsgroups: net.micro.pc Subject: Re: Re: 286 slower than 8086? - (nf) Message-ID: <423@ima.UUCP> Date: Sun, 30-Sep-84 23:40:20 EDT Article-I.D.: ima.423 Posted: Sun Sep 30 23:40:20 1984 Date-Received: Tue, 2-Oct-84 05:41:45 EDT Lines: 12 #R:sun:-170700:ima:12700002:000:498 ima!johnl Sep 30 15:11:00 1984 It's true. Loading a 286 segment register in protected mode is very slow. According to my handy 286 manual, "MOV ES,AX" would take 2 cycles in real (8086-like) mode but 17 cycles in protected mode. That's because it has to load four bytes out of the descriptor table to find out what the new contents of the segment register actually mean. Looks like a big loss if you're trying to simulate a linear address space 'cause your data doesn't naturally fall into 64K chunks. John Levine, ima!johnl