[Usagi Electric] has his Centurion minicomputer (and a few others) running like a top. One feature that’s missing, though, is the ability to produce a hard copy. Now, a serious machine like the Centurion demands a serious printer. The answer to that is an ODEC-manufactured printer dressed in proper Centurion blue. This is no ordinary desktop printer, though. It’s a roughly 175lb (80 Kg) beast capable of printing 100 lines per minute. Each line is 132 characters wide, printed on the tractor-feed green bar paper we all associate with old computer systems.
This sort of printer was commonly known as a chain printer, as the letters are on a chain that rides over a series of 66 hammers. Logic on this printer is 74 series logic chips – no custom silicon or LSI (Large Scale Integration) parts on this 47-year-old monster.
This is [Usagi’s] first time working on a printer, so he’s taking it slowly. This episode was all about bringing up the power supply. He started by disconnecting the supply from the rest of the printer, removing the dust, dirt, and mud dauber wasp nests. The supply itself is linear and included a couple of previous repairs, including a power resistor, which had been swapped for a much newer aluminum model.
The first problem [Usagi] encountered was bringing back the giant old electrolytic capacitors. He hooked them up to his bench supply and tested them. It took a bit of work, but all three caps came back to life. Reforming is a great way to save/reuse original capacitors in old equipment. Shotgunning the caps isn’t always the answer!
With the caps working, [Usagi] re-installed the supply but kept it disconnected from the rest of the machine. It came up with 5, 30, 10, and -12 volt rails. Of course, this is just the start of a much larger project, but we’re already hooked. We can’t wait to see this printer hammering away, even if it isn’t musical. Just make sure you have some hearing protection, [Usagi]!
I remember these printers well. I never had to do real repairs or maintenance, only standard operator service (replace the chain for one with upper and lower case for ‘correspondence quality’, change out the paper and multipart forms, etc) but found them to be amazing machines. I did not miss dealing with them when they were replaced in the early 1980’s, though.
You didn’t have to clean the accumulated gunge, dust and ribbon fluff out of the chains (and pretty much anywhere under the acoustic hood tbh) then? You missed out on all fun! The worst was when the company I worked for tried to save a few pennies on ribbons, and bought cheapo ones that disintegrated when worn, leaving an even bigger mess for us poor ops staff to clean up.
I remember at a previous job having to put ‘keep hands clear of paper when printer is operating’ stickers on them, after an ‘incident’ resulting in a member of the accounts department being rushed to hospital. Cleaning blood out of the rollers isn’t something mentioned in the service manual. Extremely fast and reliable printers, but noisy and a little scary. Lots of people preferred them to fussy laser printers that were always jamming and slow in comparison.
I was but a lowly assistant. Only the senior operators did more than the basic stuff. I like to think I didn’t miss any fun. Of course, when the laser printers came, I did need to regularly clean ash out of the fuser, after, of course, smacking the halon system override button, every time the Talaris smoked a page.
I never used a chain printer, but did have a couple C.Itoh dot matrix line printers.
They were big and loud; I could feel the floor vibrate when they ran. They were also a significant improvement over the run of the mill Epson, Oki, etc. dot matrix printers I had been using.
A simpler time…
Good to know I’m not the only one who’s dealt with these, albeit mine were more recently. The vibration was from the big plate printhead inside the machine that would spin in an elipse. If I remember correctly, this was done to improve print speed with a single head, you could print multiple characters in one line feed instead of character by character, line by line like a traditional dot matrix printer. We retired our last one just before the pandemic, when we finally convinced accounting to switch to laser forms. They enjoyed being able to flip page by page through the general ledge on the perforated paper. Still have a handful of odd dot matrix printer out in the wild at some locations.
I recall my first encounter with one of these chain printers, at least 30-some years ago. Being used to impact dot matrix and daisy wheel printers, I was incredibly impressed with the speed of the chain printer. I was tempted to grab a surf board and ride the wave of paper flying out of the thing!
We called Burroughs printers “line printers”, because it printed the entire line nearly at once. 132 hammers across the page, each fired as the desired character passed under it.
NCR used these printers in data centers but we called them Band printer, I guess because they were like band saws. Menards even had one at their customer service desk where the dual NCR mini-computers that ran the store were located.
DEC (Digital Equipment Corporation) called them “line printers too”. In the 80s when I did IT, we had mostly VAX and PDP systems, I never heard them called chain printers. In undergraduate school, 70s, our remote access centers, connected to Amdahl equipment, used “line printers” as well.
A chain printer would be specific type of line printer, a category that also included drum printers. In the 70s/80s, I don’t remember anyone referring to the devices in any other way than as a line printer. From the system’s point of view, it was irrelevant whether the device was a chain or drum. If I remember correctly, the DEC device mnemonic was simply LPx, with x being the printer number.
“capable of printing 100 lines per minute” – is that a typo? It feels low for such a beast?
The IBM 1443 [1] is a band printer, same system like the above shown printer. It is quoted at 150 lpm to 600 lines per minute depending on model and charset.
The Data 100 seems to be at the lower end of price and perfomance [2].
[1]: https://en.wikipedia.org/wiki/IBM_1443
[2]: http://www.pdp8online.com/shows/vcfe23/data100.pdf
I used to work for Dataproducts back in the 70s when they designed and manufactured similar line printers — a big spinning character drum, a hammer bank, tractor-feed for the green/white boxes of paper, and lots if 74XXX TTL logic.
I have worked on these the only thing that needed work on a 1970 model was some grease and a few rubber wheels that had deteriorated. It was a fun and scary printer.
For comparison, by the late 1980s, the General Electric spinoff Genicom was making huge dot matrix line printers capable of 1800 lines per minute. They required paper handlers and lots of static protection. The same factory also made high reliability relays that went into everything that went into space back then.
In the mid 80’s the entire CDC line up was represented in our computer room.
I definitely remember servicing the ChainTrain Printer.
With the diagnostic print of NASA Astronaut in EVA suit (Apollo)
Run the dead, cut the printout into 3 equal lengths, tape together. Buzz Aldrin 6 ft tall, in ASCII .
https://en.m.wikipedia.org/wiki/PAVE_PAWS#/media/File%3APAVE_Paws_Computer_Room.jpg
Better i stay away from it.
I would turn it into a different kinds of sharpe cutter noddle or pasta maker.
Look at my zigzag cut noodles or here the hokusai waves cut out noodles….
Or lasagna plates with squid ink prints on each plate.
Have noodlelicious week everybody!
And may the sauce with you!
Go look up the terror of the drum line printer. Same idea except there was a drum behind the paper with all the symbols on it, each column with a complete set, and the ribbon and hammers on the front would hit the paper exactly at the right time to print the desired symbol. If the paper jammed, the printer would often make a screaming noise until the jam was cleared..
I parted out a band printer that came with the IBM clear plastic big disc desk sized dinosaur that graced my porch 30 years ago. Neighbors complained. I still have the disc drive on the porch as an “antique” like a washtub-planter down the street. Somewhere I have the big stepper motor and the hammer strip, not sure if I saved the band.
On a slow day I remember putting a twist in the paper to form a Mobius strip. That caused some head scratching as people tried to work out what went wrong!
I was lucky to work with an unusual hybrid printer from IBM – the 4234. It was a dot-band printer. The band was a continuous piece, with chevron-shaped cutouts, and a “dot” at the peak of each chevron. So the band would fly around at high speed, and actuators would punch the dot against the ribbon, onto the paper.
It had the benefits of high-speed band printing, and the flexibility of dot-matrix, such as programmable fonts (where traditional band printers were limited to one font). So a document could be printed with multiple fonts. It could even print graphics, albeit pretty low resolution.
410 lines per minute in draft mode and 300 LPM in quality mode.
I worked in Strategic Air Command datacenters and we had these line printers as well as the monster page printer. The page printer was the next logical step of upsizing the band to full page size and having a row of hammers for each line of a full page. Those things were fun. If you took the paper out of the folder/stacker unit the printer could spit the paper straight up high enough to bounce off the ten foot ceiling. Just the item for our military that could produce documents faster than any humans could read them. I remember a particular aircraft program that was printed out for “backup” purposes even though that consumed 30 cases of paper and no human could have ever keyed it back in before it was obsolete. One of our systems had a genius routing system. If a message was intended for magnetic tape and the tape was offline, it would go to cards, then paper tape and finally to the print so the message would be “guaranteed” delivery. I got called once to pick up what was supposed to be a tape cart that instead became four cases of huge paper. I promptly took the high priority message to the incinerator and requested a retransmission.
I had one sitting next to me while working at Concurrent Computer. You definitely needed hearing protection.
Our main printer was outside my office at Macrolink, connected to our 3230 that we used for driver development and integrating new devices on our SCSI host adapters.