[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
-----------------------------------------------------------------------
Bill Frantz | Concurrency is hard. 12 out | Periwinkle
(408)356-8506 | 10 programmers get it wrong. | 16345
Englewood Ave
www.pwpconsult.com | - Jeff Frantz | Los Gatos,
CA 95032
More information about the cryptography
mailing list