Nonmagnetic digital storage at 10 bytes per second

Wednesday, September 23rd, 2009
Four years ago, almost to the day, I made a blog post about a mystery item in the Digital Sandbox. A short while later, I revealed the mystery item. Here's a new mystery item from my Digital Sandbox.

20090923 - Paper Tape Reader Punch - Front.jpgI always wanted to own the Heathkit H-10 Paper Tape Punch./Reader but when I built my first computer, a Heathkit H-8 Microcomputer with a whopping 64K of RAM, audio cassettes were popular for low-cost for data storage and I had to choose whether to build something cool - Paper Tape - or something state-of-the-art - Cassette tape. I chose the latter and was thankful every time it only took me 20 minutes to boot from cassette rather than hours booting from paper tape.

Of course, if I had chosen paper tape, I could still read my data, whereas I doubt of I can still read any of those old cassettes.

Today, I came across an old paper tape punch/reader mechanism that has been sitting in my computer museum for almost 20 years. (It's probably twice as old as that.) I don't remember where it came from of what computer I would have salvaged it from. My best guess is that it may have come from a Teletype terminal similar to a Model 35ASR, but I really do not know.

I'd like to get this working again as an I/O device, but first I will need to reverse engineer the wiring and build an interface controller for it. While I love the challenge of reverse engineering, the task much simpler if I could identify the unit and find a schematic or manual for it. I've decided to blog about this in the hopes that someday someone will Google for Teletype or Paper Tape Punch/Reader or perhaps even a DEC PDP-11 Paper Tape Interface.

Can you help me identify this mechanism?

If you can identify this mechanism and/or provide links to any resources that might help me, that would be great. I'm starting to scour the vintage computer forums as well. I'm sure someone out there has already built an interface to allow you to punch or read paper tape with a modern PC using a parallel port.

Update: After watching some YouTube videos of a Teletype terminal, I've concluded that this mechanism did not come from one of those, It may have been from a stand-alone paper tape punch/reader device.

Here are some additional photos:
Mystery Paper Tape Reader/Punch - Left Side ViewMystery Paper Tape Reader/Punch - Right Side View
Mystery Paper Tape Reader/PunchMystery Paper Tape Reader/PunchMystery Paper Tape Reader/Punch - Back SideMystery Paper Tape Punch/Reader Back Close-up

Mystery Paper Tape Reader/Punch - BottomMystery Paper Tape Punch/Reader - Bottom (Close-up)

Discussion/Comments (4):

Nonmagnetic digital storage at 10 bytes per second

Back in the late '60s/early '70s, my father, who worked for a while in computing used to bring home paper tape like that. We kids found the tapes made great streamers. But I wish that I'd kept some! (Having an actual reader - or, even better, a working reader - would be awesome.) By the time I started computing, technology had leapt forward to pencil marked cards.

(And sorry: there's no way in the world I'm going to be able to identify your tape reader. I hope someone does.)

Posted at 9/24/2009 3:26:37 AM by Anthony Holmes


re: Nonmagnetic digital storage at 10 bytes per second

Tony, those "pencil marked cards" you mention were called "Mark/Sense" cards and that's how I first learned to program on a remove timeshare computer in 10th grade. We would write our programs long-hand and then manually mark the cards. A courier would come pick up the students decks and take them to the school district headquarters. There, they would be fed into a reader and transmitted (at 50 baud) to the remote data center where the mainframe was. two days later, the courier would return with our printout. We would then debug our program and the cycle would repeat. That was using the FORTRAN language.


When we moved up to the teletype for real-time work on a remote time-sharing computer we had immediate response. Well, immediate compared to 3 days for a courier. You would write your program off-line, punch the tape, and then dial the modem (50-300 baud) and upload the program to the mainframe and then hang up. Then. 20 minutes later, the phone would ring - it would be the mainframe calling back - and we would connect the modem to receive the printout of our work on the teletype. 20-minutes round-trip. Much faster than 2-3 days by courier.

a far cry from gigahertz CPUs in our PCs and megabits of 24x7 bandwidth.

Posted at 9/24/2009 3:58:13 AM by Eric Mack


Nonmagnetic digital storage at 10 bytes per second

Not Teletype. Maybe off a Friden Flexowriter.

Posted at 9/24/2009 7:39:28 AM by Jim Haynes


re: Nonmagnetic digital storage at 10 bytes per second

Thanks, John. I took the unit apart to investigate. This is clearly a punch-only device. There is no reader mechanism.

Posted at 9/24/2009 3:36:48 PM by Eric Mack



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