[Cryptography] GHCQ Penetration of Belgacom

Bill Frantz frantz at pwpconsult.com
Wed Dec 24 10:37:43 EST 2014

On 12/23/14 at 4:12 PM, leichter at lrw.com (Jerry Leichter) wrote:

>Ah, yes, the IBM 1620 - sometimes affectionately known as CADET, for Can't Add Doesn't Even Try.

And the IBM 1401 did right to left decimal add/subtract as well. 
At least it didn't use table look up for the results like the 
1620, saving a number of memory cycles.

The Burroughs 2500/3500 machines did addition/subtraction left 
to right depending on the fact that any digits in the result 
that depend on whether there is a carry to the right will be 
either 0 or 9. The kept the address of the first of these, and 
when they knew if there was a carry, they filled in the correct 
value from left to right. A bit complex, but this was a 
Burroughs machine after all.

Cheers - Bill

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