IBM’s first tape drive turns 60

IBM’s first tape drive turns 60 today, May 21st 2012. The Model 726 Magnetic tape reader/recorder was announced just a few weeks after IBM did the same for the model 701 computer, the first electronic computer the company produced in quantity. The 701 was also known as the “defense calculator”, reflecting its intended use …

[Herby]

Actually worked on a 727 drive

Lots of vacuum tubes and all that. 200 bytes per inch on "standard" 1/2 inch tape. They took 2400 foot (10.5 inch) reels. The 727 had a nice feature that if you went far enough into the reel and asked for a rewind, it would "de-mount" the tape (wind out of the columns and raise the tape head) and rewind until it got closer to the beginning of the tape. Generally you didn't want to be just on the far side of the dividing point as the mount/de-mount sequence took quite a bit of time.

For the curious: The tapes (two fo them) were interfaced to an IBM 1620. Great fun (it was the 60's)!!

[madmalc]

RTFM

Storage density not 1 bit but 100 characters per inch

[Simon_Sharwood_Reg_APAC_Editor]

Re: RTFM

Thanks for pointing out my error, MadMalc. It was an editing mistake. I've made the changes to the text.

And FWIW IBM says density was 100 bits per linear inch http://www-03.ibm.com/ibm/history/exhibits/701/701_1415bx26.html. A 1200 foot tape therefore had 1,440,000 bits, or about 175k by my reckoning.

[Christine Hedley]

Re: RTFM

"And FWIW IBM says density was 100 bits per linear inch http://www-03.ibm.com/ibm/history/exhibits/701/701_1415bx26.html. A 1200 foot tape therefore had 1,440,000 bits, or about 175k by my reckoning."

That's probably per track, I imagine: there were seven of them...

[jake]

I'm looking for a 726 ...

... to add to my machineroom/museum/mausoleum/morgue.

And no, magtape did NOT replace card decks. It took rusty pie plates to pull that off.

[Graham Wilson]

@Jake - - Re: I'm looking for a 726 ...

"I'm looking for a 726"

Years ago when the cannibalised units came onto the disposals market, we tried to turn them into audio recorders.

Shame really, too much early computing history went this way. (I once had several Williams tube memory units out of a variant of the ILLIAC I and accidentally left them under the house when I moved. Been regretting it ever since.)

[Anonymous Coward]

Well

at least you wouldn't forget where you put the tape

[Dave 32]

Tape De-mounts

Don't forget that the tape reels were designed to be easily/quickly mounted and demounted by the operations people. Unfortunately, these mounting operations weren't completely fool proof, such that it was possible to mount a tape reel insecurely. And, when this happened, the tape reel could come flying off of the tape drive, sometimes during a high speed rewind operation. Then, the reel would go careening around the machine room floor, spewing tape. And, supposedly, in at least one case, it manage to make it out of a upper story window! Wheeeee!

Dave

P.S. Mine's the one with the tape write rings in the pocket.