[TUHS] IBM 7030 byte size (was: v7 K&R C)

Greg 'groggy' Lehey grog at lemis.com
Tue May 19 13:24:09 AEST 2020


On Monday, 18 May 2020 at  9:58:26 -0400, Doug McIlroy wrote:
>>  [A]lthough these days "byte" is synonymous with "8 bits", historically it
>>  meant "the number of bits needed to store a single character".
>
> It depends upon what you mean by "historically". Originally "byte"
> was coined to refer to 8 bit addressable units on the IBM 7030
> "Stretch" computer.

It seems that even then it was of variable size.  From G.R. Trimble,
"STRETCH," Computer Usage Communique, 1963,
(http://archive.computerhistory.org/resources/text/Computer_Usage_Company/cuc.communique_vol2no3.1963.102651922.pdf):

  the words can be composed of "bytes" with from one to eight bits in
  a byte.

There's more at https://people.cs.clemson.edu/~mark/stretch.html.

> The term was perpetuated for the 360 family of computers. Only
> later did people begin to attribute the meaning to non-addressable
> 6- or 9-bit units on 36- and 18-bit machines.
>
> Viewed over history, the latter usage was transient and colloquial

Transient maybe, but UNIVAC used the term in its documentation of the
1100 series.  The 1106/1108/1110 could access (but not directly
address) 6, 9 and 12 bit "bytes".

Greg
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