Documation Punched Card Reader Part 4 - It works again!

[@midiaz1319]

Nice T/S. I used to work for Documation in Puerto Rico. We made electrical and mechanical T/S on these readers. This was a long time ago back in 1997. Just by looking at cards, the mechanics and the esquematics really brings back memories we had making these.

[@RaymondHng]

This 6-and-a-half-minute video takes 104,863,413 bytes of storage as an MP4 file. If we were to store that file on punch cards using only eight rows (one for each bit), it will take 1,310,793 punch cards. Since each card is 0.007 inches thick, the stack of cards will be 9,175.5 inches high, 764.6 feet tall, or 656 boxes of cards at 2,000 cards per box. This card reader reading at 600 cards per minute, will take 2,184.6 minutes or *36.4 hours* to read 1,310,793 punch cards. But instead of wasting four rows, let's use use all twelve rows of the card. Then we can store 120 bytes per card. This video will take 873,862 punch cards, stacked 6,117 inches high, 509.8 feet tall, or 437 boxes. That's a lot of trees. And it will take *24.27 hours* to read them.

[@CuriousMarc]

+RaymondHng The card has 80 columns and 12 rows or "bits". Using EBCDIC character encoding (one character per column) that gives 640 bits/card. For binary data you'd use raw binary coding (packing 3 bytes into two columns), getting 950 bits/card. Of course, decks get very impractical above 10,000 cards. This still represents a decent 6.4Mb in character encoding or close to 9.5 Mb of binary data (which people would probably not attempt - they'd use 1/2" reel tape for that, which would get you up in the 20-50 MB range). For a long time this outstripped the amount of memory available core memory systems. And cost per bit was very low. Hence it's popularity.

[@RaymondHng]

CuriousMarc Hence, my second paragraph. With 80 columns of 12 punch positions, there are 960 *bits* per card or 120 *bytes* per card. And with 3 bytes represented in 2 columns, that's still 120 characters or bytes per card.

[@CuriousMarc]

+RaymondHng Ah, yes. I was trying to defend my poor punched card. It's far from being as ridiculous as it looks, particularly when you put it in perspective with memory sizes at the time.

[@jix177]

What an excellent set of statistics! Hard to reconcile those numbers to modern hardware, wonder will we be making similar comparisons some 30 years from now. Well done!

[@RaymondHng]

@@jix177 Updated stats: 16,500 punch cards weigh 99 pounds, so this stack of 1,310,793 cards will be 7,864.8 pounds. Or the 873,862 punch cards (120 ASCII characters per card) will be 5,243.2 pounds.

[@pixelflow]

That was a satisfying fix, loved seeing the analyzer read out.

[@SubTroppo]

Et Voila! Tiens! Amazing that you didn't ditch this one and take a chance on another one. The diable you know I suppose.

[@cbmeeks]

SUPERB!!! I want one of those so bad!

[@douro20]

There was one model which could do 1000 cards per minute.

[@CuriousMarc]

Yes it's called the Documation M1000. Pretty much the exact same machine and electronics, just with a faster motor. I wish I could have found one. These is a nicely shot video here kzbin.info/www/bejne/p6aYZpVmfNWae5o.