Re: [OT] bits and bytes

From: Christopher JS Vance (
Date: Thu May 17 2001 - 20:24:17 EDT

On Thu, May 17, 2001 at 03:39:02PM -0500, wrote:
: Can anyone clarify for me how big a byte has ever been? (If you could
: identify the particular hardware, that would be helpful.)

On DEC-10, with a 36-bit word, a byte was anywhere between 1 and 36
bits. They typically packed 5 ASCII-7 characters into a word with the
extra bit unused. They also packed 6 6-bit (FIELDATA) characters into
a word.

On Univac 1100 series, also with a 36-bit word, partial-word
instructions worked with bytes which were 18, 12, 9, or 6-bits. The
normal character set was 6 bits, with 6 to a word. They used 9-bit
bytes for ASCII.

I used both machines in the late '70s.

I believe some Cray machines used a 64-bit word, and put only one
character in a word, giving what might be called a 64-bit byte.

I sometime use the term 'octet' these days for 8-bit bytes. I find
most people don't like the IEC standard prefixes for multiples.
Who wants to say kibioctet instead of kilobyte (strictly 1024 octets),
or mebioctet instead of megabyte (1024*1024 octets).

Christopher Vance

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