EEVblog #663 - Compucorp 322G Calculator Teardown

Teardown Tuesday
Inside a 1973 vintage programmable scientific desktop calculator.
Plus an attempted repair.
The P2102 is a 1K x 1 bit SRAM, so looks like a 4 bit processor architecture.

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[MrCarlsonsLab]

HEY! I'm new to this youtube thing,  and have watched Dave's earlier videos too. This is my take from "fresh eyes." The man has made 663+ videos, and is still coming up with good, interesting topics. People send in their stuff for mail bag day, to see Dave tear it down, often with other requests. (what he is doing here) There is a big audience here, and all want to be appeased. So finding a balance point to please all is not so easy. I know some say he is drifting; I would rather say he is diversifying to please a growing audience. Constructive criticism can often be destructive to ones moral. If you weigh the positive comments to the "so called" constructive criticism, we can see the positive comments prevail. Dave has taken "Geek" and made it Cool! This is the reason you are here watching "and reading" this now. My advice to Dave is, don't drift from the path your on. (All those subscribers can't be wrong!) I "personally" like the diversification, and from what I can see, so do most others here. Keep up the good work Dave!

[youtubasoarus]

Always love these tear downs. The old stuff is really interesting as well as it shows us (specifically people like me who don't know) how things were done back then. Gives us a bit more appreciation for the leaps ahead in technology we've made over time.

[ChrisNorris]

Wonderful example of 70's tech. Thanks for sharing the teardown.

[zaprodk]

The D-scan board is probably not only for the display, it's for the keys, too. So one DIP40-chip for Display, and one for Keyscan. The dead cap is probably a wet-slug tantalum, failing miserably and spilling it's corrosive contents ... The "Panaplex II"-display needs around 180V to work, so your 100'ish V is too low.

[richfiles]

I am SO glad someone sent you one of these! I have a pair of similar models, but rebranded as Monroe. One working, the other not. The working one is a Monroe 344 Statistician, with dual program banks. I'll definitely be paying attention! Excited to watch this teardown! :D

[manuellujan]

Keep doing what you're doing Dave really great videos.

[Cruisey]

Display manufactured in the 48th week of 1972 - that's a week before the launch of the final Apollo mission.

[RonanCantwell]

Another good video, Dave, even if you didn't manage to get the display up and running. Sometimes we learn just as much from our unsuccessful attempts as we do from our successes. On a side note and following on from some other comments below:  I've been following these for ages now and still enjoy the content - whether that content is high or low brow. Your series on microphone design and construction was fantastic and will be a valuable resource for those working/teaching in this area. Keep up the good work and keep those videos coming, whatever they contain :O)

[MnACreations]

For what it's worth.. Dave, I like your videos very much. I am the type of person that when something doesn't work, I like to tear it apart and fix it. I enjoy watching you trace the circuits and replace the bad parts and such..  Keep up the great work.. I stumbled across your channel the other day and I am now a subscriber and looking forward to your next video.. Shoot.. I am even looking around my garage and bins to see if I have anything to send you that you would get a kick out of..

[ReligionIsBULLSHlT]

The fun of taking apart antique electronics! :)

[electronalchemy]

Dave, don't you have a nice thermal imaging camera that FLIR sent you? I can't imagine anything better for finding shorts and overheating components.

[Regular]

Great video Dave. And just so you know, I love your channel, still watch everything you post when I can, and I love the direction its going in. Just wanted you to know that there are people with you still, haha. :) Also being a fellow Aussie I will get down to come and visit you one year at a show. 

[USWaterRockets]

We really want to see what that funky display looks like. Hopefully, you can bring this beast to life, or at least hack the display panel to light some segments.

[cemx]

I was surprised that there wasn't any bypass caps at each chip like we did back in the day....

[Petex]

Thermal imaging camera could reveal the component that takes too much current

[gglovato]

That's a Burroughs corp. display!, wow!, my father used to service burroughs computers, i remember them taking one apart in the 80s, they had to do it on the front yard of our house, at least 4 people worked on it it!, each "section" was a steel frame at least 2m wide, we kept those to make awesome tables, and some of the power supplies(~25KG linear transformer and some 70000uF siemens caps that are 20cm tall)

[johnbeer]

Great vid as always. I recently got a BM257 from franky, very happy with the service and the meter. I'd like to see you do some nice useful project builds too.

[voltareamstereo]

1st, maybe
 - those the same gas plasma's as the old pinpalls?


Intel and AMD in the same device

[carterchas]

I am not surprised at the power usage.  Back when that was made, all calculators came with an alternate A/C hookup.  Most calculators did not even use batteries.  I doubt that calculator was in wide production.  It may have been a prototype.
My father bought a calculator in 1972 for $40.  All it could do was the four basic operations.  No memory button.  You had to handle subtraction like this: Instead of 10-2 = , you would enter it in as 10 + 2 - .    If you divided by 0, the display would go out (the calculator didn't know how to handle it),  
To give you an understanding of the cost, in 1972, my father could take the entire family out (two adults and two children) for $5.  Prices stated dropping for calculators around 1978 and batteries lasted longer (about two hours usage).
I think it  would be safe to estimate that calculator cost (at the time of production) to be at least $1000. 

[vehasmaa]

Nice teardown and quick overcurrent fix...