Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!harvard!godot!ima!johnl From: johnl@ima.UUCP Newsgroups: net.micro Subject: Re: 64K segments are good for you Message-ID: <507@ima.UUCP> Date: Sun, 10-Mar-85 23:39:00 EST Article-I.D.: ima.507 Posted: Sun Mar 10 23:39:00 1985 Date-Received: Tue, 12-Mar-85 21:27:50 EST Lines: 19 Nf-ID: #R:looking:-24200:ima:11700013:000:1007 Nf-From: ima!johnl Mar 10 23:32:00 1985 It's true that programs with short addresses run faster than programs with large addresses. But that's no reason to endorse a processor that insists on breaking up everything into 64K segments. The '86 series has a compact though complex instruction format, which makes programs faster since there are fewer bytes of instruction stream to decode. It's no big trick, though, to make a computer with compact object code AND linear addressing. Consider the Vax. If your programs fit in 64K, you can use 16 bit offsets in all of the instructions and your code is small and fast (the -d2 option to cc does that.) If your programs are bigger, you can use larger addresses. The NS32032, being a VAX ripoff, does the same thing. Segmented architectures have all sorts of swell advantages, viz Multics, but limiting the segments to 64K has no redeeming social value. Even Intel implicitly admits this since the 386 will have large, useful segments. Sure hope they can make it work. John Levine, ima!johnl