[TUHS] RIP John Backus

Arthur Krewat krewat at kilonet.net
Sun Mar 18 04:52:29 AEST 2018


On 3/17/2018 1:49 PM, Paul McJones wrote:
> It first ran on the IBM 704, whose index registers subtracted (as did 
> the follow-on 709, 7090, etc), so array indexing went from higher 
> memory addresses to lower.

Leave it to IBM to do something backwards.

Of course, that was in 1954, so I can't complain, it was 11 years before 
I was born. But that's ... odd.

Was subtraction easier than addition with digital electronics back then? 
I would think that they were both the same level of effort (clock 
cycles) so why do something obviously backwards logically?

ak



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