🚀 go-pugleaf

The BTSJ detailed how they developed a printer for the Transaction Telephone in 1978 (credit card verification receipts).  It goes into detail about the various issues they had to consider for the unit.  Note that in 1978 the technology and experience with it was far less than today.

The unit had to:
--print alphanumeric in upper and lower case.
--variable density with 30, 40, or 50 characters per line.
--OCR wasn't necessary as the data was already in a computer.
--printer had to handle existing documents, eg the back of checks.  
--had to be able to generate multiple copies.
--had to have flexibility to handle various sized document--led to "slip" printing.
--variable sized forms--single copy to multiple copy with carbons or NCR paper.
--speed--a typical 100 character document within 3 seconds.
--reliability--2½ years without repairs or maintenance
--oil ink, not pigment ink, so as to lubricate the pins; pigment ink is abrasive and would wear the pins.
--an inker for the ribbon was included.  Long ribbon life.
--test if paper was inserted before printing.

The above led to the conclusion to use an impact printer instead of thermal.  An off-the-shelf 7 pin commercial printer was used.

Details on the above as well the electronics needed to carry it out may be found at:

http://www3.alcatel-lucent.com/bstj/vol57-1978/articles/bstj57-10-3517.pdf

This unit was part of a series of equipment and data networks for the Bell System Transaction Network service.  This provided a faster and more economical way to verify a credit card than orally to a credit card employee.  The special telephone sets could be dial-up or attached to a special Bell System data network established for fast but short messages, such as a credit card verification request and response.

A series of articles on this system may be found at:
http://www3.alcatel-lucent.com/bstj/vol57-1978/bstj-vol57-issue10.html


Side note--thinking back to where I was and the kinds of purchases I made in 1978, the virtual cashless society we have today was still in the future in 1978.  The _commonplace_ MasterCard and Visa were still a few years away.  In 1978, many plain retail stores still verified a credit card--if one was used--by dialing up the company and orally passing the account number and amount.  I _think_ large chain department stores by then had crude card verifiers, but not as yet integrated with the cash register.  I think in 1978 most cash registers were still electro-mechanical.

Back then credit cards were pushed by the oil companies and popular at gasoline stations.  While charges for repairs were verified by phone, I don't think they bothered to verify regular charges for gasoline--it would've taken too long.

Anyway, I can't help but wonder if the Bell System network described here was a bit ahead of its time in 1978.  I have no idea how many units were actually sold.  I see these units commonly today in small retail shops, including those with dot matrix printers to generate the receipt.