From: jim bell <jimbell@pacifier.com>
Date: Fri, 12 Apr 1996 02:46:04 +0800
To: Rich Graves <llurch@networking.stanford.edu>
Subject: Re: questions about bits and bytes
Message-ID: <m0u77OB-0008yfC@pacifier.com>
MIME-Version: 1.0
Content-Type: text/plain


At 12:00 PM 4/10/96 -0700, Rich Graves wrote:
>On Wed, 10 Apr 1996, jim bell wrote:
>
>> >Be careful writing code - sometimes a byte is -128 to 127 instead of 0
>> >to 255. Also, there are machines (mostly old kinky ones) that use
>> >bytes of sizes other than 8 bits.
>>
>> No, Bill, a "byte" has ALWAYS been 8-bits.
>
>Not that it really matters, but you're wrong; if you're talking about an
>asynchronous data stream, a byte is however many bits it takes to express
>one character. If you're using ASCII, it's 8; if you're using Baudot, it's
>5. If you're talking about data in computers, then I think you're right, a
>byte is always 8 bits.
>-rich

What's the old saying, "Those of you who think you know everything are very 
irritating to those of us who do."

First off, serial binary formats for transmitted data are at least as old as 
the 1930's, and the term "byte" was coined in the early-middle 70's, as I 
recall.  Therefore it is highly unlikely (and, in fact, wrong) that the term 
"byte" referred specifically to serial binary streams.  

In fact, the term "character" is the word used to describe a serial data 
object composed of bits.  The length of that character can vary:  As any ham 
knows (or ought to know!) many early teleprinters used a so-called 5-level 
(5 bits per character; there were shift characters inserted to multiply the 
available codes) code called Baudot, while more recent ones used the 
now-common, 7-bit ASCII code.  A typical ASCII asynchronous character is 
transmitted using a start bit, seven or eight data bits, an optional parity 
bit, and one or more stop bits (usually 1, today, but it can be 1.5 or 2.)

Jim Bell
jimbell@pacifier.com