One of those magnetic fluid tape checking devices would show the bits very easily at that density (or even a lot higher). It seems to me this sort of thing should be no problem at all for the various general purpose tape reading machines that have been built, especially the ones with MR heads. So long as the reader has heads that land reasonably well on the recorded tracks, the rest is just software. Part of the software work would be reverse engineering the recording format -- NRZ or NRZI or whatever, bit layout and character set encoding, file encoding. The encoding of formatting control information will probably be guesswork, but recovering most of the plain text should be doable. paul

On 7/29/21 7:21 AM, Chuck Guzis via cctalk wrote: Digi-Data made them https://www.computerhistory.org/collections/catalog/102662523 Sadly, whoever cataloged this had no idea it was for IBM MT/ST tapes so there is no mention of MT/ST in the catalog record so I had to search every physical object record I donated to find it.

A link I forgot to include that gives a flavor of how the tapes are used: https://files.eric.ed.gov/fulltext/ED112083.pdf Curious thing is that was no take-up reel on the MT/ST; the 100 feet of tape simply was ejected loose and later rewound back into the cartridge. --Chuck

On 7/30/21 3:56 PM, Cory Heisterkamp via cctalk wrote: Not really--it's very old technology, (1964), of limited capacity (about 20 KB per tape), was a hideously expensive way to buy a typewriter (about USD$7000 in 1964, or about USD$61,000 today), used almost exclusively in large corporate offices to create form letters and documents. In other words, it was not intended as an archival medium. The effort required in preparing a document was considerable (one used the mini-keypad for various functions). For a memo, it was easiest to use the typewriter as a typewriter. There are more interesting things to look at. --Chuck

On 7/30/21 4:36 PM, Fred Cisin via cctalk wrote: One of the shortcomings of the MT/ST when compared to word processors is the lack of a good "mailmerge" option. You could code a stop code on the tape, where the typewriter would allow for manual fill-in-the-blanks operation, but that gets pretty cumbersome when dealing with hundreds of copies. Superseded by the MC/ST system, the "mag card" Selectric in 1969. Far more convenient and better integrated into the typewriter itself (no separate keypad). The MC/ST II in 1973 introduced the ability to "batch" up to 50 cards. Here's a promo film from the period, narrated by the guy driving his road yacht with the AM radio and chatting about it. https://youtu.be/bW_jJjUarp0 --Chuck

On 7/30/21 6:22 PM, Paul Berger via cctalk wrote: Like a motion picture film projector. Brings the tape to a complete stop for each character and then scans across it with a single head; going in, the character is read, going out, the character just read is checked. I assume (but am not sure) that if the check fails, a retry is attempted. The head moves at 45 ips and records bits at a 45 degree angle relative to the tape axis. This is so the tape can be scanned without moving the head for a mark in the control track (reading parallel to the axis of tape movement) or reading characters with the tape stopped (reading orthogonal to the tape movement. Obviously, precise tape positioning is important (even at 20 cpi), hence the sprocket feed. In off-list conversations with others, I keep trying to impress on the younger folks that this is basically an electro-mechanical device with heavy emphasis on mechanics. After all, the people who serviced these things were typewriter repair people. I doubt that the innards of the MT/ST were much more complex than those of the Selectric itself. (One of these days, I'll get up the nerve to replace the motor drive belt in my Correcting Selectric III). But when you've grown up with microprocessors, I guess it can be hard to envision a world with only rudimentary electronics. --Chuck

On 7/31/21 8:55 AM, Paul Berger via cctalk wrote: Did the 1620 Mod II and the 1130 use the same Selectric mechanism as the S/260 1052? I remember that the Model B on the CADET always felt as if it would shake itself to pieces every time the carriage returned. And given the relatively high failure rate for motor drive belts, why did IBM persist in making replacement such a bugger of a job? --Chuck

On 2021-07-31 1:19 p.m., Chuck Guzis via cctalk wrote: I have never seen either of these machines but looking at pictures of them it looks like the first version of 1620 had a type bar typewriter as a console.? These type bar machine would have a common heritage with the Flexowriters both are descendants of the? Electromatic company that IBM purchased in 1932 but later sold off what became Flexowriter due to anti-trust concerns. I did find a picture of a 1620 that does appear to have a selectric for a console and it looks like it is a modified OP selectric even being in the same case sunk into the desk so I suspect that it is the first version of the selectric I/O. The console on the 1130 does however look like it is a 1052 that has been integrated into the machine. Speaking of shaking apart on carriage return, I was once preparing some cash registers for the local phone company in a room where the had a HP mini that apparent ran some terminals for their subsidiary phone company in Prince Edward Island.? This HP had an ASR-33 for a console and it seemed that it printed a line for every transaction and when it would return it would slam into the dashpot on the left frame and the whole ASR-33 would rock. This mini recorded transactions on punched tape that was taken downstairs to the main computer room where it was read into the IBM mainframe on a high speed punched tape reader that looked like a 3430? tape drive with the magnet head replaced by an optical head. With regard to the position of the belt it is where it is because the selectric mechanism is split into two parts. On the left is the cycle shaft with the cams that position the type ball and through some gears turns the print shaft that drives the ball into the paper.? right in the middle running inside the appropriately named center bearing, is the hub that has the pulley on it that is driven by the motor this turn constantly.? on the left side of the the hub there is a torrington clutch? that when tripped turns the cycle shaft to print a character.? On the right side of the hub is the operational shaft that turns all the time that have clutched cams on it to operate functions such as tab and backspace, plus another torrington clutch for carriage return, and on the extreme right a cam for shift that rotate the ball 180 degrees.? It would seem that the motor belt is positioned where it is so that the entire machine could be operated from a single motor. On OP selectrics changing the belt is not such a big deal, you take out one of the gears that drives print shaft, remove the screws that hold the bearing plate on the left end of the cycle shaft and the either back off or remove entirely the cycle shaft. It was more of a challenge on the original I/O because of the presence of contact block both at the end of the cycle shaft and under the selection latches.? The original I/O was just a modified OP selectric That other than the addition of the contacts and magnets the only other change was the beefier capacitive start motor, I have seen this motor tear the teeth off a belt on a jammed machine just by turning it on.? You did not even have to look to tell if a belt was missing teeth, they had a telltale thumping noise you could hear as soon as you got close to it. The I/O II was a lot better changing belts was pretty much the same? as an OP selectric and I don't recall having to change them as often.? The worst where the machines that where in a case like an OP selectric sunk into a desk, that case and mount just made things more difficult. Part of the fun of the banking terminals was some bank branches had the machines on the counter, right where the banks customers are, and customers would often feel obliged to offer some of their wit or wisdom while you where up to you elbows in a greasy machine.? I those days of working on greasy mechanical machine we where obliged to wear suit and tie, but greasy machines where not the worst, for that there was proof machines with their purple indelible ink used to print endorsement stamps on documents. After working on them you would have purple hands for a few days. Paul.

Paul said A practice still observable on Youtube where you can marvel at a grimy oily ASR33 being stripped down and restored, all the while whilst wearing a spotless crisp ironed long-sleeve pin-striped business shirt... :) https://www.youtube.com/watch?v=pEzpYHb4p5w Steve

On 7/31/2021 8:12 PM, Chuck Guzis via cctalk wrote: A friend told me of? guy who prided him on the white shirt and tie sort of dress code despite it being unnecessary at a place he worked.? People would just shake their heads and just let it go. One morning, a lady he worked with stopped him short of going into a room where the printer were, and a burster.? "Johnny (or whatever)" is in there, you don't want to go in. He peeked in and a burster had shot carbon paper from about half a case of 4 ply all over the room and he was having to pick up the mess. thanks Jim

On 7/31/21 12:22 PM, Grant Taylor via cctalk wrote: Typo--I don't see so well in the morning. Obcously, S/360