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D.Duck D.Duck is offline
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First recorded activity by BoatBanter: Dec 2006
Posts: 1,533
Default 1956 IBM hard drive


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On Tue, 4 Dec 2007 23:27:19 -0500, "Eisboch" wrote:


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On Tue, 4 Dec 2007 17:09:22 -0500, "D.Duck" wrote:

The IBM 350 disk system stored 5 million 8-bit (7-bits plus 1 odd parity
bit) characters (about 4.4 MB).

http://en.wikipedia.org/wiki/IBM_305


Somebody needs to fix the Wiki.
It was 7 bits (remember the "odd parity"?)
The bits are 1, 2, 4, 6, A, B and parity.
It goes with "7 track tape" etc.


The most popular military teletype machines (Mod 28 ASR33) were 7 bit
ASCI
with an 8th parity or "stop" bit.

Eisboch

Eisboch


This wasn't ASCII, it was Binary Coded Decimal. The problem with even
parity is a "blank" is even. All IBM machines used some varient of BCD
before the 360 and "hex"
That was a typo above bits are 1, 2, 4, 8, A, B parity.


I think the confusion here is comparing the Teletype machines and the IBM
machine. The Teletype Model 28 is 5 bit baudot and the Teletype Model 33/35
is 8 bit ASCII.