Computer Communications 303 Keyboard Restoration, Teensy USB

[OldIsNew]

I was recently able to pick up a Computer Communications 303 keyboard.

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The PCB is marked 4-69, I'm not positive it's a date of manufacture, but I did find a brochure for the board from March 1970 and there is an inventory sticker on the back from Jan 71.

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The switches are a mechanical lever type. depressing the top lever stretches a spring and causes a second small lever contact to snap up against a contact plate.

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Switches in action:

The PCB is interesting ALL the switches are on ONE row and thus each has it's own column which runs though a row of diodes before connecting to ICs.

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Here a couple of interesting views though the PCB with back lighting:

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Since the matrix is one row with 65 columns this was a bit of an issue for one Teensy++ - so I bit the bullet and made cuts in the row trace (very small cuts with a utility knife that could easily be re-bridged) to create 4 rows and then wired up the four rows (AB, CD, EF, G) and the columns.

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Then refinished the face plate which had quite a bit of rust and cleaned up the case.

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I'm not sure it's going to make it as a daily driver, but it is fun to use!

[Chyros]

Oh wow, a mousetrap switch board Oo . I think Haata showed a disassembled numpad with them once, but I'm pretty sure it wasn't shown in action, and definitely not converted xD . Really cool to see them at work here. Amazing find and project mate!

[seebart]

Your list of awesome threads continues OldIsNew...keep up the great work!

THIS is what I only ever come to DT for anymore.

[Nuum]

That's an awesome looking keyboard! Nice find! #dta2018

Here is a video by HaaTa demonstrating how the switches work, in case somebody is wondering:

[Daniel Beardsmore]

Oh wow, a mousetrap switch board Oo . I think Haata showed a disassembled numpad with them once, but I'm pretty sure it wasn't shown in action, and definitely not converted xD . Really cool to see them at work here. Amazing find and project mate! :D

He's got the same keyboard:

photos-f62/the-original-cherry-keyboard ... 11362.html

[OldIsNew]

if anyone is curious this is a brochure for the system that used this keyboard:

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[seebart]

if anyone is curious this is a brochure for the system that used this keyboard:

I sense a wiki entry...

[DustGod]

This is beyond gorgeous.

[Sangdrax]

This is so cool.

[Redmaus]

I'm impressed with how you lined up the rows and converted the board. I always get bogged down in the details when it comes to these things. Amazing work.

[OldIsNew]

Thanks everyone for the nice comments.

A couple of other things about the board - the original key matrix is actually one row and 63 (not 65) columns because both SHIFT keys and the LOCK key are on the same column. The lock key has a mechanical latch that when pressed also depresses and latches down left SHIFT key :

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When the left SHIFT key is next pressed it releases the latch. Kind of a nice simple hardware approach to a caps lock button.



Also I think the diode matrix is one of the more interesting aspects of this board:

Diode matrix front

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Diode matrix back

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I haven't been able to find out a great deal about them so far, but apparently diode matrices can be used as encoders (as I would guess it is being used on this board) and were also used as ROM in early computers. Does anyone know more about this topic?

I sense a wiki entry...

Lol, went ahead and started one.

[JP!]

I almost bid on this one. I am glad you got it and brought it back to life. One of these days I would like to convert something like this.