Unix History: Why does hexdump default to word alignment?

[geoffrey mendelson]

On Dec 1, 2011, at 10:28 AM, Elazar Leibovich wrote:
>
> Indeed. Is there any other meaning for "word" other than two bytes?
>
> This is indeed *NOT* a very useful default on any modern computers.  
> In some
> old computers, like the PDP11 2 byte words were common and useful.

Well, let's see, going back to the 1960's, IBM 1401, word size set by  
a bit in memory, "a word mark" on a digit.

IBM 360, 32 bit words. IBM 1130 16 bit words, HP 2000/2100 16 bit  
words, CDC 6400/6600 (basis for Cray) 60 bit words. Burroughs 5500  
series used a 48 bit word. Philco 2000 (I actually used an 1000 or  
1100 (I can't remember) which was a smaller version) 48 bit word.  
SDS940 used a 24 bit word.

I was too late to use Quicktran (it was used up until June of the year  
I started 10th grade, but I did not start until September) which ran  
on an IBM 7044 with a 36 bit word.

Another high school nearby which I did not go to had a PDP 8 with a 12  
bit word.


Those were the ones I can remember having used in the time frame 1969  
to 1972.

The original Unics (later UNIX) machine was a PDP 7 with an 18 bit word.

PDP 11's were relative latecomers to the game First released in 1970.  
The PDP 11 offered Unix from the start, but most PDP11's ran a much  
less demanding operating system.

Geoff.

-- 
Geoffrey S. Mendelson,  N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(