Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!columbia!rutgers!mit-eddie!uw-beaver!apollo!perry From: perry@apollo.uucp (Jim Perry) Newsgroups: comp.arch Subject: Re: *Why* do modern machines mostly have 8-bit bytes? Message-ID: <36367aef.8e47@apollo.uucp> Date: Wed, 22-Jul-87 10:42:00 EDT Article-I.D.: apollo.36367aef.8e47 Posted: Wed Jul 22 10:42:00 1987 Date-Received: Fri, 24-Jul-87 04:28:11 EDT References: <142700010@tiger.UUCP> <2792@phri.UUCP> <8315@utzoo.UUCP> <2807@phri.UUCP> Reply-To: perry@apollo.UUCP (Jim Perry) Organization: Apollo Computer, Chelmsford, MA Lines: 16 In some old architectures the byte structure was more closely related to the input format -- Hollerith code. Thus each byte corresponded to a column on a card, with at least 12 bits: X, Y, 0..9. The Honeywell 200 (to the best of my memory, I played with this beast briefly in 1974) had these plus a parity bit and two bits called "word mark" and "item mark"; they could both be set resulting in a "record mark" (my recollection: permute well before believing). Most of the machine operations were oriented to decimal arithmetic and COBOL-style editing (zero-fill, etc), and words truly were variable length. Some operations, as I recall, scanned right-to-left until a-mark (arithmetic, presumably), others right-to-left until a -mark. I don't recall more so I won't pursue it. It's interesting in retrospect how different the use of the machine was: how many recent arcitectures incorporate floating-dollar-sign leading-zero suppression, with check-protect (asterisk fill)? Jim Perry (perry@apollo) Apollo Computer, Chelmsford MA