[TUHS] reviving a bit of WWB

Dave Horsfall dave at horsfall.org
Thu Feb 4 06:09:04 AEST 2021


On Wed, 3 Feb 2021, Peter Jeremy wrote:

> I'm not sure that 16 (or any other 2^n) bits is that obvious up front. 
> Does anyone know why the computer industry wound up standardising on 
> 8-bit bytes?

Best reason I can think of is System/360 with 8-bit EBCDIC (Ugh!  Who said 
that "J" should follow "I"?).  I'm told that you could coerce it into 
using ASCII, although I've never seen it.

> Scientific computers were word-based and the number of bits in a word is 
> more driven by the desired float range/precision.  Commercial computers 
> needed to support BCD numbers and typically 6-bit characters. ASCII 
> (when it turned up) was 7 bits and so 8-bit characters wasted ⅛ of the 
> storage.  Minis tended to have shorter word sizes to minimise the amount 
> of hardware.

Why would you want to have a 7-bit symbol?  Powers of two seem to be 
natural on a binary machine (although there is a running joke that CDC 
boxes has 7-1/2 bit bytes...

I guess the real question is why did we move to binary machines at all; 
were there ever any ternary machines?

-- Dave


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