Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!husc6!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.unix.wizards Subject: Re: Size of SysV "block" (really: byte != 8 bits) Message-ID: <2792@phri.UUCP> Date: Tue, 14-Jul-87 22:40:56 EDT Article-I.D.: phri.2792 Posted: Tue Jul 14 22:40:56 1987 Date-Received: Fri, 17-Jul-87 01:44:34 EDT References: <218@astra.necisa.oz> <142700010@tiger.UUCP> Reply-To: roy@phri.UUCP (Roy Smith) Organization: Public Health Research Inst. (NY, NY) Lines: 25 In article <142700010@tiger.UUCP> rjd@tiger.UUCP writes: > O.K., I'll byte. (oops, pun initially unintended.) A byte IS eight bits!!! > Maybe you are thinking of a word?? And a nibble is four bits, and a gulp is > sixteen bits (or was this a mouthful?), etc.... No, no, no, a thousand times NO! A byte is NOT NECESSARILY 8 bits! Granted, on most of the popular machines you are likely to see today (Vax, PDP-11, 680x0, 320xx, 80x86, Pyramid, etc, a byte is 8 bits, but that doesn't mean it has to be. A byte is simply some collection of contigious bits taken as a unit. Often a byte is that number of bits which most comfortably holds a single character in the machine's native character code, but not always. Often the number of bits in a byte is dictated by the underlying machine architecture, but that's not a hard and fast rule either. I could write a program on a Vax to read a file in 7-bit bytes if I wanted to. In fact, if I wanted to read DEC-10 tapes I would have to write just such a program (and I once did). On a DEC-10/20, for example, a byte can reasonably be anything from 1 (0?) to 36 (35?) bits; 6, 7, and 9 bit bytes are all quite common and if anything, I would say an 8-bit byte on a DEC-10/20 is a mite strange. I'm not sure byte even has a real meaning on a machine like a Cray. -- Roy Smith, {allegra,cmcl2,philabs}!phri!roy System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016