Ticker tape – in use from 1870-1970 – was the earliest digital electronic communications medium, transmitting stock price information over telegraph lines.
According to Wikipedia, it consisted of a paper strip that ran through a machine called a stock ticker, which printed abbreviated company names as alphabetic symbols followed by numeric stock transaction price and volume information.
Recently, a Maker named NeXT decided to design a custom PCB from scratch to facilitate the easy reading of paper ticker tape. As HackADay’s James Hobson notes, it is somewhat difficult to buy a working paper tape reader at a reasonable price.
“What we love about this hack is its clever reuse of perfboard — it just so happens that the spacing of his paper tape holes line up perfectly with the holes in the perfboard. Don’t you love it when engineers work together with nice, even, standard units?” Hobson writes.
“After discovering this it was just a matter of adding some photo-transistors on one side of the perfboard sandwich and LEDs on the other side. A bit of soldering, some Schmitt triggers, and an Arduino Pro Mini [Atmel ATmega168 MCU] later… and bam you have a serial output of data.”
According to NeXT, the the output can be fixed to any specific baud rate, although it is currently set at a cool 9600.
“That’s enough that I won’t overflow the serial channel, nor will it be painfully slow. It’s possible that I can change the baud rate with a jumper but I’ve yet to learn how exactly that would be programmed so we’ll leave that for another day. When I want to reprogram it the same four pin header that powers it and connects it to the host also holds an Rx pin so I can talk to it,” he says.
“In the end I decided while this makes a very nice and portable reader I decided the best home would be in my DEC LA-120 hard copy terminal. It has an option knockout on one side and you could easily build it into the overall terminal by taking the Tx line from the reader and tapping into the TxD line on the terminal’s serial port. That way so long as you were in 9600 baud mode if you wanted to read in a paper tape you threaded it through the optic block, set the computer to capture through the serial port and then pulled the tape through.”
Interested in learning more? You can check out the project’s official page here.