The longest lasting digital media technology?

I don't know if you've thought about it much but digital data storage formats change ALL the time and have relatively short lifespans and they fade away before we've copied all of our digital data to the next format.

You'd be very hard-pressed to find anyone who could read computer disks prior to the Commodore64 and Apple ][ computers.
You'd have a hard time even reading a disk from one of those "old" computers from the 1990's. I don't know of anyone anywhere who has an operating one.

Good luck if you've still got some old data on a 5.25" floppy from an early PC. Heck, I haven't even had a 3.5" floppy disk drive in any of my computers since 2002.

The National Archives digitised lots of old recordings onto DAT tapes about 20 years ago... I think you can still buy DAT players but I wouldn't count on it for much longer with cheap hard disk storage. NASA has tapes of data from the first moon landing that they can't decode because they don't have the player anymore.

With iTunes, iPods etc, even digital Compact Discs are becoming a rarity now. They were introduced back in about 1985. You can't buy a CD player anywhere now but fortunately DVD players can still play old CDs... heck DVDs - they're even begining to be superseeded by BlueRay.

Tonight at work I'm restoring data off an old 20GB IDE hard drive. It's so old and so slow but I'm glad it still operates.

There are companies that specialise in recovering digital data off old magnetic backup tapes and other formats. They make a fortune because it's hard to recover data off old dead digital storage formats.

Anyway, to my point.

What do you think is the longest lasting digital media format ever? (I'm talking about machine readable formats - not hand-written data etc)
By longest lasting I mean a format that was still being produced for many years after it first was being made. (Not a format that will last for a long time like stone tablets or handwritten scrolls in a weather protected cave)

I'll give you a tip. It ISN'T those spools of magnetic tape you see in the blue IBM computers from the 1960's, although they only stopped making those reels of tape in the last few years.

The format of digital data storage I'm talking about just stopped being produced on 3rd of January 2009.

It isn't Compact Discs, any sort of floppy disk, not hard disks, not magnetic tape, not punchcards, ... not anything even electronic!

It has been in production since 108 years ago. (That's 1901 by my watch)

It was feared in the 1920's that the introduction of radio would kill off their business.

and a final BIG clue, Nanna used to have a machine that could read the media format.

Here's a video about the format (This video was made about 20-25 years ago!)

Did you guess it?

...and here's a news story about the company finally ending the production of this digital media.