Path: utzoo!attcan!uunet!cs.utexas.edu!swrinde!dfsun1!fenske
From: fenske@dfsun1.electro.swri.edu (Robert Fenske Jr)
Newsgroups: comp.misc
Subject: Re: Punched Cards
Summary: Why 2 36-bit words?
Message-ID: <1541@dfsun1.electro.swri.edu>
Date: 7 Jun 90 13:11:11 GMT
References: <12546@netcom.UUCP> <220@taumet.COM> <12573@netcom.UUCP> <898@nlsun1.oracle.nl> <1990May29.132631.2253@pdn.paradyne.com> <1990May30.065025.25861@diku.dk> <1990Jun1.211352.4749@unhtel.UUCP> <5157@stpstn.UUCP> <124@bohra.cpg.oz> <1208@mplvax.EDU> <43535@ism
Reply-To: fenske@dfsun1.electro.swri.edu (Robert Fenske Jr)
Organization: Southwest Research Institute, San Antonio, Texas
Lines: 23

In article <43535@ism780c.isc.com> marv@ism780.electro.swri.edu (Marvin Rubenstein) writes:
>
>use as I/O devices.  Since cards were read (or punched) a row at a time it
>the computer was built to read 72 card columns at a time into two 36 bit
>words.[1]  The data from the card were presented to computer in the order:
>
> ...
>
>The card reader could, of course, read all 80 columns.  However only 72
>columns were presented to the computer.


But why 2 36-bit words?  Why wasn't it 2 40-bit words, or 4 20-bit words,
or 5-16 bit words, or 1 80-bit word?




-- 
Robert Fenske, Jr.                      Sw     | The Taming the C*sm*s series:
Electromagnetics Division              /R---\  |
Southwest Research Institute          | I    | | "The Martian canals were the
dfsun1.electro.swri.edu 129.162.160.4  \----/  |  Martians' last ditch effort."