Prototype: Using the iPhone camera to read punched tapes.

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Enrique Haro

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Jun 10, 2022, 11:13:49 PM6/10/22
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This is a basic prototype of a very low cost iOS based (iPhone or iPad) PDP punched tape reader.    

It only requires some cardboard and a shoe box. In the attached video I am manually loading the MAINDEC-8E Instruction Test 1 for the PDP-8E.    

It can reliably read 4-8 lines (8-16 Octal chars) per secon loading manually. 

I plan to implement an automatic Arduino/Raspberry-Pi based loader, it should read ~12 lines (~24 Octal chars) per second.

It was developed in Xcode 13.4 using SwiftUI and AVFoundation. The device camera is positioned ~11 cms (4 inches) from the tape.

Charley Jones

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Jun 11, 2022, 6:42:35 PM6/11/22
to Enrique Haro, PiDP-8
That’s brilliant.  Never thought of using an iPhone that way.   Well, you’re 3/4 of they way there.  I find it pretty amazing that you can process a photo that quickly in swift. 

Sent from my iPhone 12pm!
Charley Jones, PMP

On Jun 10, 2022, at 8:13 PM, Enrique Haro <enriqu...@gmail.com> wrote:

This is a basic prototype of a very low cost iOS based (iPhone or iPad) PDP punched tape reader.    
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Heinz-Bernd Eggenstein

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Jun 14, 2022, 5:12:49 PM6/14/22
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Impressive!

>I plan to implement an automatic Arduino/Raspberry-Pi based loader, it should read ~12 lines (~24 Octal chars) per second.

You might be interested in some work that has been done in high speed video capture from inexpensive Raspi-cameras, e.g.


This works by restricting the pixel field to a small "area of interest" stripe only, but that's perfect for your purpose of course.

Wouldn't it be great as well to have a printer then that could output paper "tape" of some form that could then be read-in again with this machine?
Just to recreate the old-time experience in a better way than using USB sticks as stand-ins for paper tape!

Cheers
HBE

Enrique Haro

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Jun 16, 2022, 12:12:10 PM6/16/22
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Thx for the link HBE.   Very cool.        I have seen other projects using Arduino/Raspberry P, but with leds/sensors.  Using the camera is a good approach.       My idea was to have a solution with the lowest possible cost (if any).   I am also cropping the buffer response to an area of 320x50 pixels.  We don’t have much control of the camera other than intercepting the pixel buffer and the fps is ~30 in my device.   That is a limiting factor.      For the tape loading I am experimenting with Lego motors.   Let’s see how it goes.      I will post the git repo soon…..
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