a friend of mine sent me these photos of an IBM MT/ST tape (magnetic tape / selectric typewriter).

[tubetime@mastodon.social]

@bitsavers no, i should probably do that.

[heavyimage@mastodon.social]

@tubetime this is so cool! Great work!

[bitsavers@oldbytes.space]

@tubetime

it is the system 30. I thought I had some blueprints, but i may not have put them on line

https://www.computerhistory.org/collections/catalog/102662523

I picked up the Model 30 on eBay in the 00s for CHM thinking they might be interested in reading those type of tapes in the future (hah!) then the docs showed up in a big batch of paper I bought many, many years later. Since it is now an accessioned "artifact" (because the "tool" acquisition category didn't exist), it will never be used for data recovery.
It is also the reason why I have a room full of my own card reader, disk, mag and paper tape drives at the museum that are not owned by CHM that I use for media recovery in their software preservation lab.

[tubetime@mastodon.social]

@bitsavers their logo is clever and looks just like the magnaview image.

[tubetime@mastodon.social]

@philcowans probably 1970s.

[tapewolf@meow.social]

@tubetime I will have to try and get a magnetic viewer someday, but they're not cheap

[sverx@mastodon.gamedev.place]

@tubetime you need to both bring the carriage back *and* move the paper one line

[vathpela@infosec.exchange]

@penguin42 @tubetime seems like the blank in the middle also makes sense if it's transcribed from (or merely some design bits are borrowed from) paper tape with a center tracking sprocket.

[vathpela@infosec.exchange]

@mwichary @tubetime I wonder if it's intended to be fit for mechanical transcription to some form of paper tape, without translation, and so it actually has to represent the tracking sprocket holes.

[mwichary@mastodon.online]

@vathpela @tubetime That’s exactly what I was thinking of, too!!!

[deborahh@cosocial.ca]

@tubetime @ShaulaEvans what?!?!

[carpetbomberz@mastodon.online]

@tubetime @bitsavers

All the *kewl kids are doin' it

[tubetime@mastodon.social]

@mwichary @vathpela possible but also the documentation refers to a search bit, so presumably you could set a marker bit there.

[bitsavers@oldbytes.space]

@carpetbomberz @tubetime

and thanks to @tubetime someone will have figured it out for them, assuming "doin' it" means reading old magtape selectric cartridges

[carpetbomberz@mastodon.online]

@bitsavers @tubetime

that is what doin' it means in this context ️

[vathpela@infosec.exchange]

@tubetime @mwichary making that a dedicated bit instead of a symbol sure seems weird.

[snowfox@tech.lgbt]

@tubetime Interesting bit numbers. 1, 2, 2a(?), 5, 10, 20; maybe it was originally for a decimal system?

The * on the 2's Ck/Sft suggests it supports both uppercase and lowercase (lining/text?) digits which is interesting since there's no separate 1, so no way to encode "lowercase" 1.

[acsawdey@fosstodon.org]

@tubetime So is the MT/ST before or after the "Magcard Composer" which was basically a Selectric that could key in text and store it on what looked like a punch card but was covered with magnetic media. Then you'd put in the expensive mineral-coat paper and play it back to get a nice error-free galley that you could paste up into book form. Low end typesetting in the late 1970's ...

[mwichary@mastodon.online]

@vathpela @tubetime I don’t know what “search” is exactly and Internet Archive is down, but if it’s something like beginning of a new section, I can see the value of a separate hole – it could potentially allow to find sections faster (random access)?

[somevegancheeseisok@mastodon.social]

@tubetime holy shit this is so cool