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From: e142-aq@hercules.Berkeley.EDU (Alan Nishioka)
Newsgroups: sci.electronics
Subject: Credit card encoding
Message-ID: <28174@pasteur.Berkeley.EDU>
Date: 25 Sep 90 19:30:40 GMT
Sender: news@pasteur.Berkeley.EDU
Reply-To: e142-aq@hercules.Berkeley.EDU (Alan Nishioka)
Organization: University of California, Berkeley
Lines: 24


Does anybody know how information is encoded on the magnetic stripe for
credit cards, bank cards, my student id, etc.?  Any references?  A trip
to the library and looking thru the reader 's guide didn't get me anywhere.

I just bought a card reader which had 5 ttl level outputs.  Two for each
of 2 head tracks and a 5th that goes low when a card is being run thru.
The chips don't seem to be identifiable.

I discovered that cards seem to use two different levels of stripe, for
a total of 4 tracks on my bank card, but only two on my student id, which
are at the wrong level for my reader.

Looking at the bank card with magnaview film (from Edmund Scientific)
I can see two levels of stripes, so maybe only two tracks are actually used.

The code must be self-clocking and I would guess just have simple 
error checking (parity) since the card can just be run thru again if
necessary.

BTW, I just want to read, not commit bank fraud :-)  I would have to build
another card input/output assembly for that :-)
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Alan Nishioka			atn@cory		...!ucbvax!cory!atn