Getting started with AVR and C

You still have your ADM-3A!!?! Wow. I built one of my own from the kit that Lear Siegler offered, around the time I also built my Altair 8800 from kit. (I was WAY TOO POOR to just go buy assembled stuff at the time.) It was so wonderful to have that ADM-3A. I don't even know where it went, now.

Now that brings back pleasant memories. I used that thing like crazy for years. It saved my life when writing programs under CP/M, for example. Or using Microsoft's paper tape BASIC. (Hmm... I bet I still have a Persei drive maybe and maybe also some old 8" floppies with Microsoft's BASIC on them.....)

hehe. The mechanisms aren't as impressive as the 35. But it's nice to see that. I never used or saw a 28, though. Thanks!

I still have my old DECtapes in plastic cases around here -- no tape drive for them, though. So there they sit.

I'm going to build another tape reader and tape punch, though. The reader is easy. It's the punch dies for the tape punch that will set me back, time wise. I think to think about the design some more. But I want to design, make, and build that project. My son would benefit from it and I'd enjoy it.

Jon

Reply to
Jon Kirwan
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Mechanical dies???? A couple hundred Watts of CO2 laser, a rotating drum mirror, and an AVR for timing should suffice! ;-) (Bonus prize---no chad---hanging or otherwise)

Mark Borgerson

Reply to
Mark Borgerson

Hmm. Although I lose out on the memory of the sound of it, there is an advantage to your suggestion. I could also then use it to laser cut plywood and other slabs of wood, do art work, and so on. Wonder if tilting the rotating mirror would then let me do scan lines without having to move a heavy target on a table.

Nah. The paper is oiled well. Probably would catch fire on me. And if it didn't, the hole rim would be darkened and I'm not sure what that does to some of the readers. Wouldn't feel right, either.

I think drill rod is the right way to go, don't you? :)

Jon

Reply to
Jon Kirwan

When I worked in a Navy comm center back in the '70s, we had dozens of punches and teleprinters running 24-7. We collected chad by the pound each watch. It got re-used: if someone dozed off, they often got well sprinkled with chad. A second incident in too short an interval brought a rubdown with used carbon paper. (Yes, it is possible get sleepy in a room full of teleprinters.)

Experienced operators carried a mini punch to clean up partial punches or hanging chad. The telecomm relay process at that time involved receiving and decrypting the messages from the far East in Hawaii, then moving the paper tapes to the next reader to encrypt and retransmit to DC, and to local commands.

Mark Borgerson

Reply to
Mark Borgerson

I think it is better to use Mark's 21st century solution :) With that you should be able to engineer a Tbyte life instead a 100K byte life for a mechanical punch that would cost more to implement :) Probably 100-1000 times as fast.

On another group recently someone calculated the volume and read times for a TByte on cards

The other contest would be to design and implement a reliable Rube Goldberg. My entry is Roman 5 flag signaling to remote output on cuneiform tablet engraving and baking in Baghdad.

w..

Reply to
Walter Banks

Hehe. I'm tempted. A little scary setting up a few hundred watts of 10 micron IR beam, though. (or is it 15 micron?) Anyway, don't these things COST A LOT? (Like thousands of dollars for the tubes?)

Here's a 20W tube:

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And that by itself is $400.

Here's another, more expensive one:

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I've no idea how long these tubes last. Their warranties appear to be no more than 10 months, though. So I'm betting on replacement once per year or more often, ignorant as I am of these beasts.

Do you have any specific recommendations about how to keep the costs down, the power adequate, and the precision appropriate for the task of cutting precision holes in thick, oiled paper?

I'm still thinking drill rod, myself. It's not as though I'm going to be cutting out Tbytes on paper tape. I think the rolls are only from one supplier:

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With shipping, it's $415.51 for (28) 1000' rolls. So 28000' or 3.36 megabyte for only $415.51. A terrabyte would cost me merely $123,663,690.00. That, plus the CO2 laser and operating costs.

... would put me only slightly over budget!

You wouldn't happen to have some lucrative projects around, would you, where I could earn enough for this hobby?

;)

Hehe.

I think I'll just get serious about drill rods and have somewhat more modest fun. I can't afford these hobbies of yours!! A terrabyte done on paper tape! Cripes.

Jon

Reply to
Jon Kirwan

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Many years ago (1972 I think) I bought 4 PDP-11's and negotiated main memory down to $1 per byte and became an 11 second hero. Yesterday I was in a hardware store that had scattered all over the store stocking stuffer

8G thumb drives for $7.95 and also scatted all over the store LED flashlights for $8.95. Who would have believed in 1972 an unimaginable amount of storage for less than the cost of a flashlight.

If you are serious about drill rod it will be a a real learning exercise in metal physics, strength of materials, lubrication. A good starting point might be the art and science of Samurai swords.

Remember while you are at it that the cost each roll of paper tape would buy two 8G thumb drives.

I smell coffee..

Good Luck :)

w..

Reply to
Walter Banks

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If it's the paper tape that is the key, not the method of storing data, perhaps a paradigm shift is in order.

  1. you could lower the laser power to the point where you just char the paper a bit and use an optical reader.
  2. Use an ink-jet print head to print the 'holes' and an optical sensor to read the tape.

IIRC, fast optical readers showed up near the end of the paper tape era. I think there were even plans for do-it-yourself readers in the magazines of the time. If I get time, I'll take a look in some of my magazines from the era. (I saved the ones that printed my articles.)

Mark Borgerson

Reply to
Mark Borgerson

Sounds like paperbytes all over again. At a couple K bytes per page it would still take a lot of paper for a Tbyte.

:)

w..

Reply to
Walter Banks

Before optical readers, there were fast capacitive readers with paper speeds of several meters per second, thus several kilobytes/s, filling the core memory with operating system and program in tens of seconds.

You could get deep nasty wounds, if you accidently touched the fast moving paper tape. Thus, it was a good idea to use gloves, when operating the paper tape reader.

Reply to
upsidedown

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If it were the case that I was looking at these as storage of programs, rather than a fun experience, I'd use a flash drive or a local server system. (Well, I actually DO use them.) But this is about the experiences. I don't mind making it easier on myself (for example, buying an already existing punch head with solenoids, too) and then adding electronics to the rest.

But it's not about storage. Well, except perhaps things I may want to have survive 1000 years, perhaps (can't do that with DVDs, CDs, or any other magnetic media that I'm aware of -- paper is amazing stuff for really long term storage.)

I'm not afraid of the learning exercises. By the time I was

20, I'd built three telescopes (1000s of hrs of work on each, grinding and then testing the figure and then more grinding, etc., and then the rest that makes it serviceable.) I also built my Altair 8800 from the newly available kit and when I later bought the 4k dynamic ram cards that were designed wrong and could not work, I got a huge lesson struggling to fix them (about a dozen patches I made to get them going.) And I didn't know enough about how dynamic ram worked, when I started, either. So unknowns are fine. Just need to push through them.

Jon

Reply to
Jon Kirwan

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Yeah, but the reader I'm building uses a linear lamp overhead and a glass stirring rod to focus it onto the holes, with sensor LEDs underneath. I guess I could consider working on things so that it works okay with either holes or "inked" dots. Might not be too hard to do. Will think on it.

But I lose the ability to have good storage for millennia. Holes in papertape will easily last a millenia, and more. Maybe I want to communicate with neo-humans 10,000 years from now and say "hi," eh?

I built my own optical reader in the late 1970's. Hand pulled, though. I used the sprocket holes to create a trigger pulse to sample the other holes, so it didn't matter that much how fast I pulled. Mostly, I just didn't want the tear the papertape.

(I could not afford to buy stuff, then. Raised very poor, lived in homes without walls, had to work the fields to survive as a kid. So I wasn't like young adults born in middle class families who could just go out and buy a reader or a punch or an assembled computer, etc. I had to make almost every finished product I got to own. This included the ADM-3A that someone else mentioned -- I could only barely manage the kit cost.)

Jon

Reply to
Jon Kirwan

Now there's a thought. I never got close enough to the fast ones, except rarely. And I didn't know how they operated. But I did, at the time, understand how to make an optical one work and made my own. (It is long gone, now.) I hadn't even considered a capacitive approach.

Could you elaborate a bit on this?? I'm interested in the approach -- particularly the sensor/transducer part of it and perhaps the 1st stage concerns (the rest of the amplification and electronics I think I can work out.)

Jon

Reply to
Jon Kirwan

I have never seen any schematics for these beasts, but they had 8 (or more likely also a 9th for the feed hole) trimmer capacitors very close to the read head.

My guess is that some kind of bridge construction was used, with the actual sensor and the trimmer capacitor at opposite side of a bridge circuit.

Reply to
upsidedown

I guess a punched card (with a serial number in columns 73-80) made from some more durable material would be a good way to send such messages.

Reply to
upsidedown

I used a Facit reader (500 / 1000 characters/s) in late 1960's. It was nearly the very best available.

There was a row of pins flush with the tape transport plane,

8 larger for data and the ninth smaller for feed holes, which were between 3th and 4th data holes. There was a common electrode on top of the tape (in the tape path cover). The cover electrode was fed with a 500 kHz signal, and the pins were connected to the opposite phase of the feed with trimmer capacitors, so there was a bunch of 9 capacitance bridges. The bridges were adjusted to balance with a fully-punched piece of tape in place.

For feeding the tape, there was a capstan rotating at the reader speed, and in the cover there was a bearing for pushing the tape against the capstan. The bearing was pulled by a armature lever and a electromagnet when there was a need to feed. For quick stopping, there was a similar lever before the reading position, without the bearing and capstan. This mechanism allowed the sub-millisecond timing needed for the speed.

The ultimate tape reader was built by Danish Regnecentralen. It solved the question of very abrupt motion of the paper tape and reels needed for top speed. There were servo-controlled reels for input and output tape, and the feed was performed with a servo-controlled capstan. The whole mechanism resembled that of the 1/2 inch magnetic tape drives. Also, there was a FIFO buffer in the electronics, and its filling level was used to control the servos. The top speed was 2000 characters / s.

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Tauno Voipio
Reply to
Tauno Voipio

The holes will probably outlast the tape. "Time Team" is one of my favorite shows, and they're continually trying to deduce, since dirt right here is a slightly different color from the dirt over there, that Saxons must have built something out of wood.

Mel.

Reply to
Mel Wilson

The WW II code-breaking computer Colossus read its paper tape at 5000 characters per second. They had run with up to 9700 characters per second before the tape broke. But the Colossus tape was a fixed loop, endlessly repeating, not a long tape on a reel. And the speed was constant, not start-and-stop, so high speed was easier.

Ref:

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Niklas Holsti 
Tidorum Ltd 
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Reply to
Niklas Holsti

Ah. The difference between ancient paged codices and scrolls.

Hmm. Do I want future historians to handle codices or scrolls of mine? Must think on that problem. ;)

Jon

Reply to
Jon Kirwan

Cool, yet another reason for holes rather than ink spots on paper.

Jon

Reply to
Jon Kirwan

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