It was more than Hypnotic. I worked for Honeywell in the sixties and one customer Unbrako in Coventry England had eight tape drives. I used to run systems check which operated EVERYTHING. When these monoliths ran, writing, reading, fast forward and fast back, it was like an orchestra playing. The low growl when reading back and the high pitch on the rewind. I wish that i could have recorded it. Music to my ears.
You think of the detectives waiting for the investigator researchers to get a computation result. The tapes are spinning and the film noir detective is waiting and pondering what the results could be alas an op code is invalid.
@@Microsoft-WindowsAlphaville, the movie released six years after this iconic IBM vacuum column tape drive, might have checked all the boxes. Except that it didn't, as it didn't feature the IBM 729. Still a good 1965 film noir if you ask me. Regardless, I guess I've watched this RUclips video far more often than the Eddie Constantine movie. Side note: in MS Teams meetings, my background shows an ancient date center with some vacuum column drives. While the precision might be less than noteworthy by today's standards, the sheer brutality and power they utilized to that goal is unsurpassed.
When I was a boy in the '80s I used to think that every time an old movie or TV program showed a mainframe's tape unit, their prop department had gotten it wrong. I was used to playing around with my father's old Akai reel-to-reel tape recorder, and my grandfather's Wollensak -- the reels both turn in the same direction and at the same time. It wasn't until many years later that I was able to research IBM's vacuum-column technology and appreciate how innovative and impressive their tape units were and still are.
We had some old mini-computers that used 9-track reel-to-reel tapes like these (but not exactly, ours were made by Pertec). When we had some 'suits' scheduled for a tour, we were told to 'Make it look like the computer is doing something'. So we would queue up an old tape-to-tape sort program (even though we normally did large data sorts directly to the disk drive). So when the 'suits' came in, they got to see the reel-to-reel tapes jerking back and forth, just like old movies and they were duly impressed. lol
Many years ago I refurbished an IBM 727 tape drive (predecessor to your 729). The 727 had vacuum tube logic (plus lots of relays), but the motor drive design was almost the same as your 729. The brushes were OK, but the powdered iron and graphite mixture inside the tape reel shaft clutches had rusted so the reel was trying (unsuccessfully) to turn both ways at once. Disassembly, cleaning, and reassembly of the clutches was a real chore! But I got it all working OK after troubleshooting a bunch of the vacuum tube logic - and learned a lot in the process.
Fabulous Video !!! I spent many hours inside the computer room of an IBM 360 and I was always amazed at the incredible speed and quickness of those tape drives, and the slack tape hanging down inside their vacuum chambers. When the IBM repairman came around, he was dressed in a suit and carried a suitcase full of the most beautiful exquisite tools. The type you might see in Switzerland. IBM made precision top world quality machinery, and the tools to maintain and repair IBM equipment were equally impressive.
@@DevynCairns Having worked at IBM for a year in the early 90s.... You wore a suit for everything, although you may take the jacket off. Crawling around chasing cables? Suit. Clearing up after a printer decided to launch loose toner across a room? Suit. Maneuvering 1/2 ton tape drives around server rooms? Suit!
As an ex Magnetic Tape Drive Engineer working out of the UK - see this problem and how you resolved it brought back many sweet memories. Awesome work. I was smiling as much as you all were at the end. Bravo
Yep and you could keep your lunch cool down there. There were many occasions when I'd be working on cables, with my feet through the hole in the floor, getting very cold!!!
A little bit of electronics ? Geez, will you look at all those discrete components boards ! And 8 motors ! Wow ! What an incredible piece of engineering. No wonder it was so expensive back in the day. Fascinating piece of machinery. Thanks for this detailed inside view and explanations. Congrats to all of you on fixing it. This video made me subscribe. What is the maximum digital data transfer speed of a tape unit like this ?
The maximum data transfer speed of this particular unit, a 729-II, is (6 bits per character) times (556 characters per inch) times (75 inches per second) = 250,000 bits per second. Other models of the same drive with a faster transport (112.5 inches per second) and higher density (800 characters per inch) could transfer up to 540,000 bits per second.
All that size, mechanical complexity, and electricity - and even an old junk 286 could outpace this machine with ease. It's astonishing how far technology has progressed in such a short period of time.
"even an old junk 286 could outpace this machine with ease" - actually no, these systems supported hundreds of terminals simultaneously. What they had that your 286 is lacking is THROUGHPUT Every peripheral device in the system had an intelligent controller that was an entire computer in itself. I know because I was a mainframe computer operator in the 70s and 80s - you could not imagine a more fascinating job or place to work.
@@James_Knott my favourite job of all times was computer room shift supervisor. I.B.M. really fumbled when they handed the industry to Microsoft on a silver platter.
Well this neat, back in 1996 my electronics class disassembled a 1401 series computer, 720 tape drives and backup power system as a class project. At the end it all was sold as scrap metal I did manage to keep one tape machine (I bought it for $50) and got it working, It's in my storage building now bubble wrapped up and tarped.. Along with a honeywell mainframe and hard drive rack. I have a personal collection of vintage communications and computer hardware. I have one of the original World of Warcraft server blades also.
Three years late into a thread, as usual, that's what the RUclips Algorithm does to me. This brings back many more memories, although I have to say, these brutes are far more complicated than the CDC machines I worked on in the mid seventies. That kit was probably mid to late sixties in origin. The CDC's were vacuum column machines, but there the similarity ended, pretty much. The Reel Hubs were direct drive, reversible motors - quite meaty things - but none of that coaxial clutch, slip rings and fast rewind motors. I think they had five motors, including the vacuum pump. Two reel motors, the vacuum pump and the two capstan motors. The capstan was a finely ground, forged (I think) cylinder about 75mm in diameter and a bit wider than the tape - say, 15mm? The circumference had a series of semicircular groves, not quite full width, with a hole drilled into the plenum chamber underneath. Now that I think about it, there were probably two capstans, although I just don't remember. One for forward read/write, one for reverse read/write. I'm almost sure they could do that? So the capstan/s(?) were on either side of the read/write section and the left one hauled tape out of the supply column and the right hand one shoved tape down into the take up column. Next to the read/write head was a fixed block with holes in, which was the tape brake, also vacuum operated. They revolved at constant speed (the read/write speed) in the appropriate direction and the tape was moved by sucking it against the capstan. To stop, the vacuum was released on the plenum and applied to the brake. There was virtually no momentum because all the mass was being driven by the reel motors and controlled by the columns. Loading a tape was very easy. You just pulled the leader off the supply reel as it hung down and pulled it across the top of the capstans, the brake and the heads and wound it on to the take up reel. Then you closed the door and hit 'LOAD'. The vacuum would come on and suck tape down both columns until they stabilised, then the tape wound forward until the EOT marker was detected. Then the READY lamp would come on and, with any luck, the deck would go online automatically and work could commence. I have other memories about slip rings, but that was on CT Scanners and many, many years later. Thanks for a great series, Marc.
Great video! I love 1401s, they were such a big improvement over the 402 accounting machine! Spent many happy hours programming these puppies. Almost wish I had one. :-) One minor correction - disk drives existed at the same time as these tape drives. All the 1401 systems I used had multiple disk drives and no tape drives. Tape access was generally faster than disk access if you were doing a sequential update job, but a compile from a disk drive was a heck of a lot nicer than compiling from tape!
OK. I thought the 729 vacuum column tapes predated the RAMAC (first hard disk) by a bit. I'll double check. But yes, later on you could hook up a RAMAC disk unit to the 1401. [edit] Indeed you are right: 729 tape is 1958, and the first RAMAC is 1957!
However, the 729 was first introduced as a minor modification of the 727 tape drive, adding a two-gap head. The 727, in turn, was an improved version of the 726 tape drive from 1952.
I used drives similar to these in which the window in front of the tapes would lower for unloading and loading. We used to place the tape volumes of multi-tape master files on control box at the top of the drive. Later, the company bought STC drives, and the windows on those would raise up through the control box. It didn't take long to learn to put the to-be-used master volumes in a separate (and inconvenient) rack. So many memories seeing that printer and the 1401 control panel!
0:02 Notice the large panel flooring in this IBM 360 computer room. All the wiring and cooling for the machinery ran under the floor. The computer itself required this specially-built room, and computer rooms all looked quite similar in every company which owned an IBM computer. Beautiful space-age modern equipment. It still looks futuristic six decades later.
It might be ancient, obsolete & nowadays a watch calculators probably millions of times faster & more memory efficient, but I was fascinated by the complexity of these wonderful pieces of engineering.So much so I want to know where I can buy one!
you should see 8 tape drives doing a sort! You specify the input drives, how many work drives, and the o/p drive. while 1 i/p drive was in rewind it was reading from the other. that was called phase 1, the input phase. then phase 2 was the sort phase, then finally phase 3 was the o/p phase. after phase 1 (i/p phase) you can mount scratch tapes on the two input drives, then the printer will tell you how any passes of the data has to be made to have the data in sequence before the final phase 3. simply amazing! tape sort were much faster than disk sorts too! watching the tape drives reading and writing both forwards and backwards during phase 2 was very cool. I used to write sort exits in assembler, for the sort program. these exits can modify the data on all 3 phases. all this was done on a machine with 16K, that's 16 thousand bytes of memory!
@@simonknights7526 actually tape sorts are MUCH faster than disk sorts. I used to know the programmer reslonsivle dornthe sort program and wrote tons if E15, E25 ans E35 sort exits. The sort program would constantly evaluate rhe best algorithm to use as the sort progressed. What i find amazing is that on a tape sort, you can specify the specific output drive even though it is used as a work drive as well. Also after the input phase is done, you can use the input drives as wirk drives After you mount scratch tapes on then. You could also use alt input tapes drives as well and both would be used as work drives adter the input phase. It was amazing to me that after the input phase, it would display hiw many passes of the data it would take to complete the sort.
@@rty1955 Interesting! But I don't understand how the tape sorts were faster that disk sorts - could you explain please? The first machine I worked with only had two 2311 disks (7.25MB each - one held the OS, and the other had the Fortran and Cobol compilers, and other support libraries) so could not be used for any sort work areas. When those 2311s were replaced by a number of 2314 disk drives we then switched to using the disks as work areas for sorts -because sorts were so much faster that way. But watching a tape sort was something else!
I had never considered, just how much ‘mechanical’ goes into the more modern computational rigs. And more recently even, it is not at all apparent until you try to change your ink cartridge, or even more applicable is storage devices. Mechanical engineering really is a precursor in all things electronic, to where we’d be nowhere if it weren’t for our ability to predict the mechanical implications of anything. SO AWESOME!! You know what you’re doing is important when the World wants you to film every minute of it!!
Thank you so much for your time and effort on both making these videos and keeping these amazing machines in working order. I very much look forward to your next video.
I never knew they sounded like that while reading and writing the tape! I knew these computers would be complex, but geez, the electronics in there are a marvel in itself.
Wow. I'm blown away. I think there's as much mechanical work involved in this machine as electronic work in some modern systems. These are the days when finding bugs involved real bugs lol.
The little black plastic rollers that push the tape against the capstan to move or against fixed round rubber cylinders to stop are called prolays, one on either side.
I had a job when I was 13 (1979) at our city municipal building, loading tapes, changing printer ribbons, and loading punched cards. the equipment was the same or very similar to that. my mother altered my birth certificate so they would hire me.
MANY THANKS for putting this on. Ever since I was at school in the 1960's I've wanted to know how these tape drives work. You've certainly made an older man very happy.
It's really fascinating to see how these drives work. Being shown the inner workings it all makes good mechanical sense - I had always vaguely wondered what sort of mechanisms were used to drive the reels and control the recoil of the tape. Never would I have imagined that there was a vacuum channel employed there!
Thank you for the great video! These tape drives are what got me interested in computing originally and I miss them a lot. You all have some of the best jobs I can imagine!
Thanks for this video! I ran across it while doing some research into the function of these tape drives. Also thanks to the IBM 1401 team for the documentation on your website. The 729 CE Manual found there is newer and more informative than the version on bitsavers. It was quite interesting to see the repair of the clutch brushes. It makes me curious about how other maintenance items are handled. There's a lot of old technology there that's going to need occasional repairs.
Worked on similar units to these as late as the 80's in the Air Force. They used them to load programs onto a CENPAC unit and run automated test stations for maintenance on F-111s.
The old bus and tag. I remember when we replaced those connectors with fiber. During the next big earthquake in California, the cables did not hold the disk drives in place anymore. They flew around the room as a result causing great damage. After that experience they had to retrofit special feet on the disk drives to keep them from flying around. Who woulda thunk that a fiber cable wouldn't secure those big drives to the floor anymore!!
Love those tape drives, they are as much mechanical as they are electronic. I remember seeing them as a kid in the early 80's and thinking how awesome they looked.
Love to see that there are people that still know how to maintain these old systems.. I loved working on this sort of equipment, really well built and some amazing engineering solutions.
In 1974 I was programming an IBM 1401, GE 225 with drum memory. In 1975 I moved to a IBM 370-135 DOS machine these were all in college. I graduated in 1977 went to work for the USAF doing systems development on a IBM 7080 and a CDC Cyber 170 running SCOPE. There just nothing like the smell of a hot IBM 24 and 80 column cards at 03:00 in the morning
Maximum respect to you guys for your time and dedication to keeping these amazing machines going. The random movement of the reels on these drives has always fascinated me. Thanks for sharing this. I worked for DEC many years ago, though I'm not sure they produced a vacuum column drive. Maybe you know....? All the best !!
these machines are built like steam trains they will last for years to the earth dies while modern computers will last 5 years and die due to the life cycle of silicone and transistors and the caps on the boards
Are those gentlemen in red shirts former customer engineers? Imagine repairing these in the old days with your white shirt and tie on (required) to project the air of professionalism. Many white shirts were ruined and no expense reimbursements. IBM had boat loads of part numbers! Once an amazing place to work with a great group of amazing people!
Man, I have the utmost respect for those two older gentlemen..those guys really knew what they were doing, you couldn't count on Google helping you out when something didn't work. Amazing video!
One thing I don't miss, cleaning the read/write heads. We experimented with different brands of tape, and finally bought a 'tape cleaner' that would zip the tape quickly from end to end, dragging it over a sort of 'cleaning head' so the old tapes wouldn't leave dirt on our tape drive heads.
I also used to clean tape and disk heads. The operators had a machine that cleaned the tape and also checked for wear. I also had to remind a couple of programmers to not smoke around the computers.
Awesome job guys! I'm sure no serious company on earth can reproduced the quality of these monsters now days! (And nobody can have your talent and passion about these pieces of history) The great "electromechanic" era. hope to see a Silicon Graphics or Intergraph wokstation on your channel! Best regards from France.
Every part of this is a learning experience. I'd never even heard of silver epoxy. Now I'm left thinking of all the things that would have been the perfect tool for and I'd kludged. Well, if all you have is a hammer, everything looks like a nail.
I used to work with Teac and HP mag tape units from the 80s / 90s on Ericsson AXE10, IOG3 & IOG11, not as impressive as those units, but still rose tinted memories. That's for posting the video.
Awesome video, it gives "Mechanical drive" a new meaning. Thanks for uploading it. Wow 20MB that must have been like 20TB back in the day, given most programs used a few KB.. I just subbed to your channel:D
I'm shocked by how complicated the inside of that 9-Track tape machine is. In the 70's I worked at SoBel date centers in Miami and Ft Lauderdale, as part of an on-site maintenance team of three guys. We had about 40 or more Telex drives, I think they were 6450's. The reel motors were direct drive no belts, no clutches. The capstan motor, there was only one, was a permanent magnet motor with an armature that was a fiber glass disk with heavy wires bonded to it that was about 1/4 in thick and maybe 8" in diameter. The capstan wheel mounted to the armature had vacuum applied to grip the tape. It had to accelerate to full speed and write it's block of data and decelerate to stop while maintaining the about 1/2" gap between blocks of data. It had about five to six vacuum switches per tape column. And I really did love my job. All these machines were very well engineered, and were workhorses. It was great fun.
We need a place to send the pictures of the data centers we worked at. Tape drives at Sobel were made by Telex. When I starterd at Sobel they were using an RCA 3301 computer. I had zero IC's in it. And a lot of sketchie board contacts which were all gold plated. Core memory was in a sealed box. Used a daisy wheel printer as a console. Later changed to an modified IBM Selectric.
the engineering is fascinating, but the fact that you could actually repair most if not all of it, that's the really awesome part, well, at least compared to today's standards
This was soo cool to watch all the way to the end. What a great demo of the tape drive that is soo cool that you got it repaired! Thank you soo much for sharing! I remember seeing these in action when I was a kid. I have a friend long been retired now that worked with these in a meat processing plant. I remember seeing them run at IBP in Dakota City. I remember my Dad as a clerk at the railroad used punch cards to keep track of train cars at Chicago Northwestern RR.
Back in the 80s, when I was a computer tech, I maintained several tape stands, on a couple of different systems. However, on those, they had servo motors, so need for clutches or slip rings. They also measured the air pressure, to control the tape reels. Also, there was one occasion when a TV crew wanted to film the data centre operation and they didn't think the tape stands looked like they were working. So, we ran diagnostics to make them look busy. 🙂
Yep. Been there, done that, got the T shirt! I started in the telecom business overhauling Teletype machines and later got into computers, with some other stuff in between.
2 years ago, I made a two brushes, using with knife for common electric drive. I lost something about 5 hours on this job, but motor is working everytime! Greetings from Russia, and thanks a lot for these awesome unicue video, Author! These videos must watching in schools :) Oh my God, sorry for my English
Brings back memories! I was a field engineer with Burroughs in the late 70's / early 80's, and we had rather similar units. A bit more sophisticated electronics and motors, higher speeds, but the same basic principle. Many 'fond' memories of trouble-shooting those beasts!... Ahh, the good old days...
Just a bunch of old computer nerds. I am jealous. As a child of the 80s I have never had the chance to learn much about these old drives or tech of the pre home computer era.
These old tape drives brings back memories, the vacuum tape drives were far better than the modern drives that were attached the AS400 computer in the early 90’s. In that day there were ancient tape drives attached to a 4381 but boy were they fast. In those days IBM built quality and I was proud to work for IBM.
Wow! Thank you so much for creating this video! I had never seen the inner working of machines like these. It is still amazing what people developed back in the days and it is funny to see all these young guys at work (including yourself at the lathe ;-) ) to get the machine working fine again. Thank you Marc.
Wow, really amazing machine, and excellent work fixing it. I would love to someday get up close and personal with a mainframe like this the way you guys do.
There are still naval warships using tape drives. When I retired in 2014, the FFG-7 Class guided-missile frigates and some US Coast Guard gun-armed ships were transitioning over to CDs, but some, especially several foreign FFG-7s in nations with fewer funds for conversions and upgrades, were still using them. The tape drives are not IBM, but made by Sperry UNIVAC, all to "Mil-Spec" and MUCH more solid and heavy than the IBM drives you show here (half-inch steel frames and eighth-in steel cases, with heavy lock clamps around the doors to keep out water, etc.). The older drives, UNIVAC 1540s, were somewhat similar to the 1401 drives, but instead of a vacuum tape reserve buffer in two long tubes, they had a series of spring-loaded short arms with rollers at their tips. When you put tape through the machine from the source reel to the take-up reel, you threaded your tape through a narrow gap across all of those rollers, through the read/write head block, through another set of cushion arms, and onto the take-up reel, hand rotating everything to be tight. Then you hand-rotated the source reel forward a few turns (not quite to the LOAD POINT silver tape mark) to make sure it was secure on the take-up reel. This caused the two sets of arms to spread apart forming a pair of "W"s of tape, each arm of the W about a foot long, one on each side of the read/write block. You made sure the tape was not loose anywhere and then turned on the power. The arms suddenly spread apart even more and tightly held the tape and each arm could pivot under spring loading at its base, allowing more or less tape in the interval between the two reels, as needed, this being the cushion for fast tape motion that those two vacuum tubes do on your IBM drives. All loading was manual, including running the tape past the LOAD POINT silver tape mark and then manually pressing LOAD to cause the machine to move the tape forward and then backward to the LOAD POINT to be ready to run. Later, the UNIVAC 1840 drives appeared to slowly replace many, but not all, of the 1540s. These used a vacuum tube system like your IBM drives do, but not visible unless you opened up protective steel doors on the drive face, and were automatic: All you had to do was put the source tape on its reel shaft, lock it, and then feed the end of the tape into a small slot in the central read/write block, which was much bigger than used with a 1540. When you hit LOAD, the tape was sucked into that slot, the tape ran onto the take-up reel, the vacuum cushion inside turned on, and the tape was then positioned at the LOAD POINT silver tape mark ready to run. I assume that inside all of these machines, they were just as, if not more so, complex as yours are.
I used to work on some Collins 8500 computers. These were mil spec versions of IBM gear and built for use on ships. They were also built like tanks and water cooled! I had to use a fork lift to swap disk drives!
I envy you, Americans, simply for having museums about old computers and getting to see them in action. We, în Europe, especially Romania where I live, do not have that opportunity. It would be a dream come true for me to see an 1959 computer fully operational
Don't misunderstand. There's almost nothing like this in the world. There is *a*. museum for old computers. There are obviously displays elsewhere in science museums but I have never heard of any other computer museum.
It's rather beautiful to watch that tape machine work. The action of the reels is rather soothing and hypnotic.
I'd have it over a lava-lamp any day.
It was more than Hypnotic. I worked for Honeywell in the sixties and one customer Unbrako in Coventry England had eight tape drives. I used to run systems check which operated EVERYTHING. When these monoliths ran, writing, reading, fast forward and fast back, it was like an orchestra playing. The low growl when reading back and the high pitch on the rewind. I wish that i could have recorded it. Music to my ears.
You think of the detectives waiting for the investigator researchers to get a computation result. The tapes are spinning and the film noir detective is waiting and pondering what the results could be alas an op code is invalid.
@@Microsoft-WindowsAlphaville, the movie released six years after this iconic IBM vacuum column tape drive, might have checked all the boxes.
Except that it didn't, as it didn't feature the IBM 729. Still a good 1965 film noir if you ask me.
Regardless, I guess I've watched this RUclips video far more often than the Eddie Constantine movie.
Side note: in MS Teams meetings, my background shows an ancient date center with some vacuum column drives.
While the precision might be less than noteworthy by today's standards, the sheer brutality and power they utilized to that goal is unsurpassed.
When I was a boy in the '80s I used to think that every time an old movie or TV program showed a mainframe's tape unit, their prop department had gotten it wrong. I was used to playing around with my father's old Akai reel-to-reel tape recorder, and my grandfather's Wollensak -- the reels both turn in the same direction and at the same time. It wasn't until many years later that I was able to research IBM's vacuum-column technology and appreciate how innovative and impressive their tape units were and still are.
Same here!! Thought I'd try to find out what was happening :)
We had some old mini-computers that used 9-track reel-to-reel tapes like these (but not exactly, ours were made by Pertec). When we had some 'suits' scheduled for a tour, we were told to 'Make it look like the computer is doing something'. So we would queue up an old tape-to-tape sort program (even though we normally did large data sorts directly to the disk drive).
So when the 'suits' came in, they got to see the reel-to-reel tapes jerking back and forth, just like old movies and they were duly impressed. lol
@@mikefochtman7164 At my company we ran diagnostics to make them look busy for a TV crew. 🙂
Blue screen "Read/write error sector 00001011"
IT technician starts the lathe.
Awesome video!
Locutus of Borg encountered a write error at sector 001
Maybe because all the Borg were sleeping.
Benoit De Brueker Naaah, oscilloscope!
Sector 11 in big-endian? Or sector 208 in little-endian?
We're talking about an IBM machine, that'd be a read/write CHECK ;)
You're the only one to make a video showing the inside of these! Thanks for the interesting video, I've wondered how those worked
LeiserGeist Bobby
*That boy ain't right.*
Many years ago I refurbished an IBM 727 tape drive (predecessor to your 729). The 727 had vacuum tube logic (plus lots of relays), but the motor drive design was almost the same as your 729. The brushes were OK, but the powdered iron and graphite mixture inside the tape reel shaft clutches had rusted so the reel was trying (unsuccessfully) to turn both ways at once. Disassembly, cleaning, and reassembly of the clutches was a real chore! But I got it all working OK after troubleshooting a bunch of the vacuum tube logic - and learned a lot in the process.
I would never had guessed the existence of that vacuum tape buffer system. It's like a mechanical cache, genius.
Fabulous Video !!! I spent many hours inside the computer room of an IBM 360 and I was always amazed at the incredible speed and quickness of those tape drives, and the slack tape hanging down inside their vacuum chambers. When the IBM repairman came around, he was dressed in a suit and carried a suitcase full of the most beautiful exquisite tools. The type you might see in Switzerland. IBM made precision top world quality machinery, and the tools to maintain and repair IBM equipment were equally impressive.
Repairing mechanical equipment in a suit sounds like a challenge. I'm sure they had to get them dry-cleaned often too.
@@DevynCairns Having worked at IBM for a year in the early 90s.... You wore a suit for everything, although you may take the jacket off. Crawling around chasing cables? Suit. Clearing up after a printer decided to launch loose toner across a room? Suit. Maneuvering 1/2 ton tape drives around server rooms? Suit!
As an ex Magnetic Tape Drive Engineer working out of the UK - see this problem and how you resolved it brought back many sweet memories. Awesome work. I was smiling as much as you all were at the end. Bravo
The sound of that computer room brings back memories. They even have the raised floors ...love it.
Yep and you could keep your lunch cool down there. There were many occasions when I'd be working on cables, with my feet through the hole in the floor, getting very cold!!!
A little bit of electronics ? Geez, will you look at all those discrete components boards ! And 8 motors ! Wow ! What an incredible piece of engineering. No wonder it was so expensive back in the day. Fascinating piece of machinery. Thanks for this detailed inside view and explanations. Congrats to all of you on fixing it. This video made me subscribe.
What is the maximum digital data transfer speed of a tape unit like this ?
The maximum data transfer speed of this particular unit, a 729-II, is (6 bits per character) times (556 characters per inch) times (75 inches per second) = 250,000 bits per second. Other models of the same drive with a faster transport (112.5 inches per second) and higher density (800 characters per inch) could transfer up to 540,000 bits per second.
540,00 is only 67.5 Kilobytes per second or 0.067 Megabytes per second. Yes, it really was that slow.
Actually this hasn't really changed with modern tape drives like LTO; still a handfull of motors in those, just at a miniaturized scale.
@SteelRodent yes I know the struggle firsthand :-) I was referring to the original comment about the mechanical aspect and the number of motors.
@@simontay4851 same my internet connection...!
All that size, mechanical complexity, and electricity - and even an old junk 286 could outpace this machine with ease. It's astonishing how far technology has progressed in such a short period of time.
"even an old junk 286 could outpace this machine with ease" - actually no, these systems supported hundreds of terminals simultaneously. What they had that your 286 is lacking is THROUGHPUT
Every peripheral device in the system had an intelligent controller that was an entire computer in itself. I know because I was a mainframe computer operator in the 70s and 80s - you could not imagine a more fascinating job or place to work.
@@vap0rland I was a computer tech back in the 80s and worked in a data centre on several different systems.
@@James_Knott my favourite job of all times was computer room shift supervisor. I.B.M. really fumbled when they handed the industry to Microsoft on a silver platter.
@@vap0rland IBM picked up the government contracts though while Microsoft was playing in the sandbox.
I love the mechanical solutions to electronic problems all through-out these older machines
Watching the brushes being made was so oddly satisfying.
Well this neat, back in 1996 my electronics class disassembled a 1401 series computer, 720 tape drives and backup power system as a class project. At the end it all was sold as scrap metal
I did manage to keep one tape machine (I bought it for $50) and got it working, It's in my storage building now bubble wrapped up and tarped.. Along with a honeywell mainframe and hard drive rack.
I have a personal collection of vintage communications and computer hardware. I have one of the original World of Warcraft server blades also.
What's the spec of the WoW blade?
I'd buy the Tape drive & disk drives. But I already know your answer. lol was worth a try to get a bite
In my electronics class I dismantled a radar transmitter/receiver, complete with magnetron!
Machines from when I was a young man. Good show on why those things were so expensive. Well done.
It's astounding to me the ability of the enginiers to design around the things they couldn't do in electronics.
Three years late into a thread, as usual, that's what the RUclips Algorithm does to me. This brings back many more memories, although I have to say, these brutes are far more complicated than the CDC machines I worked on in the mid seventies. That kit was probably mid to late sixties in origin.
The CDC's were vacuum column machines, but there the similarity ended, pretty much. The Reel Hubs were direct drive, reversible motors - quite meaty things - but none of that coaxial clutch, slip rings and fast rewind motors. I think they had five motors, including the vacuum pump. Two reel motors, the vacuum pump and the two capstan motors.
The capstan was a finely ground, forged (I think) cylinder about 75mm in diameter and a bit wider than the tape - say, 15mm? The circumference had a series of semicircular groves, not quite full width, with a hole drilled into the plenum chamber underneath. Now that I think about it, there were probably two capstans, although I just don't remember. One for forward read/write, one for reverse read/write. I'm almost sure they could do that?
So the capstan/s(?) were on either side of the read/write section and the left one hauled tape out of the supply column and the right hand one shoved tape down into the take up column. Next to the read/write head was a fixed block with holes in, which was the tape brake, also vacuum operated. They revolved at constant speed (the read/write speed) in the appropriate direction and the tape was moved by sucking it against the capstan. To stop, the vacuum was released on the plenum and applied to the brake. There was virtually no momentum because all the mass was being driven by the reel motors and controlled by the columns.
Loading a tape was very easy. You just pulled the leader off the supply reel as it hung down and pulled it across the top of the capstans, the brake and the heads and wound it on to the take up reel. Then you closed the door and hit 'LOAD'. The vacuum would come on and suck tape down both columns until they stabilised, then the tape wound forward until the EOT marker was detected. Then the READY lamp would come on and, with any luck, the deck would go online automatically and work could commence.
I have other memories about slip rings, but that was on CT Scanners and many, many years later. Thanks for a great series, Marc.
This is one of the coolest things, I am really happy someone appreciates the antiques enough to keep them running. It's like a classic car.
What an amazing insight how these tapes actually work...
Great video! I love 1401s, they were such a big improvement over the 402 accounting machine! Spent many happy hours programming these puppies. Almost wish I had one. :-)
One minor correction - disk drives existed at the same time as these tape drives. All the 1401 systems I used had multiple disk drives and no tape drives. Tape access was generally faster than disk access if you were doing a sequential update job, but a compile from a disk drive was a heck of a lot nicer than compiling from tape!
OK. I thought the 729 vacuum column tapes predated the RAMAC (first hard disk) by a bit. I'll double check. But yes, later on you could hook up a RAMAC disk unit to the 1401. [edit] Indeed you are right: 729 tape is 1958, and the first RAMAC is 1957!
However, the 729 was first introduced as a minor modification of the 727 tape drive, adding a two-gap head. The 727, in turn, was an improved version of the 726 tape drive from 1952.
It's amazing how much length they went through to run that tape at speed.
OMG!!! my C: partition belt tensioner has broken
I used drives similar to these in which the window in front of the tapes would lower for unloading and loading. We used to place the tape volumes of multi-tape master files on control box at the top of the drive. Later, the company bought STC drives, and the windows on those would raise up through the control box. It didn't take long to learn to put the to-be-used master volumes in a separate (and inconvenient) rack. So many memories seeing that printer and the 1401 control panel!
0:02 Notice the large panel flooring in this IBM 360 computer room. All the wiring and cooling for the machinery ran under the floor. The computer itself required this specially-built room, and computer rooms all looked quite similar in every company which owned an IBM computer. Beautiful space-age modern equipment. It still looks futuristic six decades later.
It might be ancient, obsolete & nowadays a watch calculators probably millions of times faster & more memory efficient, but I was fascinated by the complexity of these wonderful pieces of engineering.So much so I want to know where I can buy one!
No, it was much more memory efficient in the 1950s than it is today.
you should see 8 tape drives doing a sort! You specify the input drives, how many work drives, and the o/p drive. while 1 i/p drive was in rewind it was reading from the other. that was called phase 1, the input phase. then phase 2 was the sort phase, then finally phase 3 was the o/p phase. after phase 1 (i/p phase) you can mount scratch tapes on the two input drives, then the printer will tell you how any passes of the data has to be made to have the data in sequence before the final phase 3. simply amazing! tape sort were much faster than disk sorts too! watching the tape drives reading and writing both forwards and backwards during phase 2 was very cool.
I used to write sort exits in assembler, for the sort program. these exits can modify the data on all 3 phases.
all this was done on a machine with 16K, that's 16 thousand bytes of memory!
Absolutely. Filming a SORT7 run is on the to do list.
So many memories of watching tape sorts on 2401 drives on a 360/40. I do miss that on modern machines.
@@simonknights7526 actually tape sorts are MUCH faster than disk sorts. I used to know the programmer reslonsivle dornthe sort program and wrote tons if E15, E25 ans E35 sort exits. The sort program would constantly evaluate rhe best algorithm to use as the sort progressed. What i find amazing is that on a tape sort, you can specify the specific output drive even though it is used as a work drive as well. Also after the input phase is done, you can use the input drives as wirk drives After you mount scratch tapes on then. You could also use alt input tapes drives as well and both would be used as work drives adter the input phase. It was amazing to me that after the input phase, it would display hiw many passes of the data it would take to complete the sort.
@@rty1955 Interesting! But I don't understand how the tape sorts were faster that disk sorts - could you explain please? The first machine I worked with only had two 2311 disks (7.25MB each - one held the OS, and the other had the Fortran and Cobol compilers, and other support libraries) so could not be used for any sort work areas. When those 2311s were replaced by a number of 2314 disk drives we then switched to using the disks as work areas for sorts -because sorts were so much faster that way. But watching a tape sort was something else!
@@CuriousMarc Did you film the SORT7 tape sort? I've looked but can't find it - would be great to see!
So iconic... I remember how computers were represented in any cartoon, until the 1980s: a cabinet with two reels 😊.
I had never considered, just how much ‘mechanical’ goes into the more modern computational rigs. And more recently even, it is not at all apparent until you try to change your ink cartridge, or even more applicable is storage devices. Mechanical engineering really is a precursor in all things electronic, to where we’d be nowhere if it weren’t for our ability to predict the mechanical implications of anything. SO AWESOME!! You know what you’re doing is important when the World wants you to film every minute of it!!
Thank you so much for your time and effort on both making these videos and keeping these amazing machines in working order. I very much look forward to your next video.
I never knew they sounded like that while reading and writing the tape! I knew these computers would be complex, but geez, the electronics in there are a marvel in itself.
Amazing, i didn't knew how complex the tape unit was, fantastic, thank you for sharing this.
Wow. I'm blown away. I think there's as much mechanical work involved in this machine as electronic work in some modern systems. These are the days when finding bugs involved real bugs lol.
The little black plastic rollers that push the tape against the capstan to move or against fixed round rubber cylinders to stop are called prolays, one on either side.
I never knew that they used clutches for the reels! Suddenly the abrupt motion makes perfect sense!
I've seen these tape drives in countless movies,TV shows, etc...Never knew they were so intricate
I had a job when I was 13 (1979) at our city municipal building, loading tapes, changing printer ribbons, and loading punched cards. the equipment was the same or very similar to that. my mother altered my birth certificate so they would hire me.
Brilliant work! Few things are as cool to watch as those old tape drives. Thanks for sharing a peek at the inner workings!
Techmoan's PC.
Silver Spoon yes...
The era when there was money to be made in IT!
IT technicians using lathes - brilliant.
Now technicians are on the minimum wage, sad times.
Wonderful to see familiar old technology. "When computers looked liked computers!" and you could immediately SEE that they were working properly.
MANY THANKS for putting this on. Ever since I was at school in the 1960's I've wanted to know how these tape drives work. You've certainly made an older man very happy.
On your fingers, no nail Polish. I really respect that. Thank you.
It's really fascinating to see how these drives work. Being shown the inner workings it all makes good mechanical sense - I had always vaguely wondered what sort of mechanisms were used to drive the reels and control the recoil of the tape. Never would I have imagined that there was a vacuum channel employed there!
What a wonderful look into the past. Hard to imagine how far we've come since then being it wasn't that long ago.
As a mid 90s child that used VHS tapes, seeing that fast rewind is curiously satisfying.
This amazing machine was in operation even before robots were saying "Danger, Will Robinson!"
Thank you for the great video! These tape drives are what got me interested in computing originally and I miss them a lot. You all have some of the best jobs I can imagine!
Was fascinated watching these guys work on this stuff we have come such a long way
This is why I love vintage computers, you have to be not only an electrical engineer, but a mechanic too!
Theres a few electronics inside of it....."opens it" HOLY JESUS
@@snaplash And a ton of relays!
Looks like a nightmare to fix if something went wrong
Yeah, just a "bit"... understatement of the century.
@@simontay4851 it's been a bit
My thoughts entirely lol
How many still watch such video?? this one is awesome. thanks for the details...........you folks make thing work out interesting for us!! kudos!!
Thanks for this video! I ran across it while doing some research into the function of these tape drives.
Also thanks to the IBM 1401 team for the documentation on your website. The 729 CE Manual found there is newer and more informative than the version on bitsavers.
It was quite interesting to see the repair of the clutch brushes. It makes me curious about how other maintenance items are handled. There's a lot of old technology there that's going to need occasional repairs.
Worked on similar units to these as late as the 80's in the Air Force. They used them to load programs onto a CENPAC unit and run automated test stations for maintenance on F-111s.
those connectors were epic
Tom P. They look like from the 1800s
Now _they_ are proper connectors! They will last forever.
The old bus and tag. I remember when we replaced those connectors with fiber. During the next big earthquake in California, the cables did not hold the disk drives in place anymore. They flew around the room as a result causing great damage. After that experience they had to retrofit special feet on the disk drives to keep them from flying around. Who woulda thunk that a fiber cable wouldn't secure those big drives to the floor anymore!!
Love those tape drives, they are as much mechanical as they are electronic. I remember seeing them as a kid in the early 80's and thinking how awesome they looked.
Love to see that there are people that still know how to maintain these old systems.. I loved working on this sort of equipment, really well built and some amazing engineering solutions.
I always wondered why the units were so big compared to the size of the tape reel - very interesting!
In 1974 I was programming an IBM 1401, GE 225 with drum memory. In 1975 I moved to a IBM 370-135 DOS machine these were all in college. I graduated in 1977 went to work for the USAF doing systems development on a IBM 7080 and a CDC Cyber 170 running SCOPE. There just nothing like the smell of a hot IBM 24 and 80 column cards at 03:00 in the morning
Thank you for sharing this. I have always wanted to see how such a tape drive works. Fascinating bit of machinery.
Maximum respect to you guys for your time and dedication to keeping these amazing machines going.
The random movement of the reels on these drives has always fascinated me.
Thanks for sharing this.
I worked for DEC many years ago, though I'm not sure they produced a vacuum column drive. Maybe you know....?
All the best !!
these machines are built like steam trains they will last for years to the earth dies while modern computers will last 5 years and die due to the life cycle of silicone and transistors and the caps on the boards
This is the exact kind of video needed 10 stars Marc! You have generated all kinds of hope..........
Carbon-brushers are also needed in washing-machines, mine is repaired. Nice to see them made.
Kind regards.
I remember seeing that card sorter back in 1965 ... it was cutting edge in those days :)
Are those gentlemen in red shirts former customer engineers? Imagine repairing these in the old days with your white shirt and tie on (required) to project the air of professionalism. Many white shirts were ruined and no expense reimbursements. IBM had boat loads of part numbers! Once an amazing place to work with a great group of amazing people!
Red shirts? This better not be Star Trek! 🙂
Wow, I saw the inside of these giants for the first time! It is like "when computers used to look like heavy machinery!"
Thanks for the insight.
I have aways liked the erratic movement of those old tape machines.
quite fast and advanced for the time.
The enginerring complexity of that time to accomplish something so simple we take for granted today is amazing. IBM hired the best.
Wow, a lot of motors for just one drive! Very interesting! I even see a 9th motor in there. I guess that's for a cooling fan. Right?
Yes, it's a fan motor. Two or thre of these, rather big.
Man, I have the utmost respect for those two older gentlemen..those guys really knew what they were doing, you couldn't count on Google helping you out when something didn't work. Amazing video!
One thing I don't miss, cleaning the read/write heads. We experimented with different brands of tape, and finally bought a 'tape cleaner' that would zip the tape quickly from end to end, dragging it over a sort of 'cleaning head' so the old tapes wouldn't leave dirt on our tape drive heads.
I also used to clean tape and disk heads. The operators had a machine that cleaned the tape and also checked for wear. I also had to remind a couple of programmers to not smoke around the computers.
Awesome job guys!
I'm sure no serious company on earth can reproduced the quality of these monsters now days!
(And nobody can have your talent and passion about these pieces of history)
The great "electromechanic" era.
hope to see a Silicon Graphics or Intergraph wokstation on your channel!
Best regards from France.
I could watch that all day, everyday. Great work guys.
There’s something deeply satisfying about actually fixing these old things instead of just letting them collect dust all broken down 🖖
Every part of this is a learning experience. I'd never even heard of silver epoxy. Now I'm left thinking of all the things that would have been the perfect tool for and I'd kludged. Well, if all you have is a hammer, everything looks like a nail.
I used to work with Teac and HP mag tape units from the 80s / 90s on Ericsson AXE10, IOG3 & IOG11, not as impressive as those units, but still rose tinted memories. That's for posting the video.
The most interesting video I've seen in a while!! I love when people keep cool old machinery like this running.
Awesome video, it gives "Mechanical drive" a new meaning. Thanks for uploading it.
Wow 20MB that must have been like 20TB back in the day, given most programs used a few KB..
I just subbed to your channel:D
I'm shocked by how complicated the inside of that 9-Track tape machine is. In the 70's I worked at SoBel date centers in Miami and Ft Lauderdale, as part of an on-site maintenance team of three guys. We had about 40 or more Telex drives, I think they were 6450's. The reel motors were direct drive no belts, no clutches. The capstan motor, there was only one, was a permanent magnet motor with an armature that was a fiber glass disk with heavy wires bonded to it that was about 1/4 in thick and maybe 8" in diameter. The capstan wheel mounted to the armature had vacuum applied to grip the tape. It had to accelerate to full speed and write it's block of data and decelerate to stop while maintaining the about 1/2" gap between blocks of data. It had about five to six vacuum switches per tape column. And I really did love my job. All these machines were very well engineered, and were workhorses. It was great fun.
These are 7-track drives.
We need a place to send the pictures of the data centers we worked at. Tape drives at Sobel were made by Telex. When I starterd at Sobel they were using an RCA 3301 computer. I had zero IC's in it. And a lot of sketchie board contacts which were all gold plated. Core memory was in a sealed box. Used a daisy wheel printer as a console. Later changed to an modified IBM Selectric.
the engineering is fascinating, but the fact that you could actually repair most if not all of it, that's the really awesome part, well, at least compared to today's standards
This was soo cool to watch all the way to the end. What a great demo of the tape drive that is soo cool that you got it repaired! Thank you soo much for sharing! I remember seeing these in action when I was a kid. I have a friend long been retired now that worked with these in a meat processing plant. I remember seeing them run at IBP in Dakota City. I remember my Dad as a clerk at the railroad used punch cards to keep track of train cars at Chicago Northwestern RR.
Back in the 80s, when I was a computer tech, I maintained several tape stands, on a couple of different systems. However, on those, they had servo motors, so need for clutches or slip rings. They also measured the air pressure, to control the tape reels. Also, there was one occasion when a TV crew wanted to film the data centre operation and they didn't think the tape stands looked like they were working. So, we ran diagnostics to make them look busy. 🙂
Fascinating! I often wondered how those tape machines worked. A computer tech would have to be a mechanical expert as well as an electronics one.
Yep. Been there, done that, got the T shirt! I started in the telecom business overhauling Teletype machines and later got into computers, with some other stuff in between.
2 years ago, I made a two brushes, using with knife for common electric drive. I lost something about 5 hours on this job, but motor is working everytime! Greetings from Russia, and thanks a lot for these awesome unicue video, Author! These videos must watching in schools :) Oh my God, sorry for my English
Brilliant. I always wanted to look inside one of these units but never imagined it would be so complicated. Very interesting.
Brings back memories! I was a field engineer with Burroughs in the late 70's / early 80's, and we had rather similar units. A bit more sophisticated electronics and motors, higher speeds, but the same basic principle. Many 'fond' memories of trouble-shooting those beasts!... Ahh, the good old days...
I think it is interesting that the lathe used to make the brushes has more processing power than the 1401
Wow, computers of this era really were *machines*. A computer system running with v-belts and clutches!
Just a bunch of old computer nerds. I am jealous. As a child of the 80s I have never had the chance to learn much about these old drives or tech of the pre home computer era.
i remember these at various places that i worked that used main frames . never got to see the innards . thanks .
These old tape drives brings back memories, the vacuum tape drives were far better than the modern drives that were attached the AS400 computer in the early 90’s. In that day there were ancient tape drives attached to a 4381 but boy were they fast. In those days IBM built quality and I was proud to work for IBM.
Wow! Thank you so much for creating this video! I had never seen the inner working of machines like these. It is still amazing what people developed back in the days and it is funny to see all these young guys at work (including yourself at the lathe ;-) ) to get the machine working fine again. Thank you Marc.
This is amazing!!! I wonder what all the fun projects you could do with this today!!!
Seeing this operate in 2016 makes me eager to see it in action.
Wow, really amazing machine, and excellent work fixing it. I would love to someday get up close and personal with a mainframe like this the way you guys do.
This video is a thing of beauty. Thank you for the tour. Very detailed. Excellent.
There are still naval warships using tape drives. When I retired in 2014, the FFG-7 Class guided-missile frigates and some US Coast Guard gun-armed ships were transitioning over to CDs, but some, especially several foreign FFG-7s in nations with fewer funds for conversions and upgrades, were still using them. The tape drives are not IBM, but made by Sperry UNIVAC, all to "Mil-Spec" and MUCH more solid and heavy than the IBM drives you show here (half-inch steel frames and eighth-in steel cases, with heavy lock clamps around the doors to keep out water, etc.). The older drives, UNIVAC 1540s, were somewhat similar to the 1401 drives, but instead of a vacuum tape reserve buffer in two long tubes, they had a series of spring-loaded short arms with rollers at their tips. When you put tape through the machine from the source reel to the take-up reel, you threaded your tape through a narrow gap across all of those rollers, through the read/write head block, through another set of cushion arms, and onto the take-up reel, hand rotating everything to be tight. Then you hand-rotated the source reel forward a few turns (not quite to the LOAD POINT silver tape mark) to make sure it was secure on the take-up reel. This caused the two sets of arms to spread apart forming a pair of "W"s of tape, each arm of the W about a foot long, one on each side of the read/write block. You made sure the tape was not loose anywhere and then turned on the power. The arms suddenly spread apart even more and tightly held the tape and each arm could pivot under spring loading at its base, allowing more or less tape in the interval between the two reels, as needed, this being the cushion for fast tape motion that those two vacuum tubes do on your IBM drives. All loading was manual, including running the tape past the LOAD POINT silver tape mark and then manually pressing LOAD to cause the machine to move the tape forward and then backward to the LOAD POINT to be ready to run. Later, the UNIVAC 1840 drives appeared to slowly replace many, but not all, of the 1540s. These used a vacuum tube system like your IBM drives do, but not visible unless you opened up protective steel doors on the drive face, and were automatic: All you had to do was put the source tape on its reel shaft, lock it, and then feed the end of the tape into a small slot in the central read/write block, which was much bigger than used with a 1540. When you hit LOAD, the tape was sucked into that slot, the tape ran onto the take-up reel, the vacuum cushion inside turned on, and the tape was then positioned at the LOAD POINT silver tape mark ready to run. I assume that inside all of these machines, they were just as, if not more so, complex as yours are.
I used to work on some Collins 8500 computers. These were mil spec versions of IBM gear and built for use on ships. They were also built like tanks and water cooled! I had to use a fork lift to swap disk drives!
Absolutely awesome exhibit and work to get the tape drive working! Wow!
I envy you, Americans, simply for having museums about old computers and getting to see them in action. We, în Europe, especially Romania where I live, do not have that opportunity. It would be a dream come true for me to see an 1959 computer fully operational
We just put them down here.
Even if they function fine, they're just tossed down for people to look at.
Sad that they have to die like that.
Don't misunderstand. There's almost nothing like this in the world. There is *a*. museum for old computers. There are obviously displays elsewhere in science museums but I have never heard of any other computer museum.
I believe that the older the technology, the more beautiful it is
The engineering of these machines is fascinating!