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Re:The long road to recover Frogger 2 source from tape drives by bsder on Wednesday May 24, 2023 @03:06PM (#36062645)
Is there way to read magnetic tapes like these in such a way as to get the raw magnetic flux at high resolution?

It seems like it would be easier to process old magnetic tapes by imaging them and then applying signal processing rather than finding working tape drives with functioning rollers. Most of the time, you're not worried about tape speed since you're just doing recovery read rather than read/write operations. So, a slow but accurate operation seems like it would be a boon for these kinds of things.

Re:The long road to recover Frogger 2 source from tape drives by fifteen1506 on Wednesday May 24, 2023 @03:40PM (#36062981)
You still need to know where to look, the format, and using specialized equipment which cost wasn't driven down by mass manufacturing, so, in theory yes, in practice not.

(Completely guessing here with absolute no knowledge of the real state of things)

Re:The long road to recover Frogger 2 source from tape drives by iforgotpassword on Wednesday May 24, 2023 @03:54PM (#36063128)
Sounds like at least in this case that ASIC in the drive was doing some (non trivial) signal processing. Would be interesting to know how hard it would be to get from the flux pattern back to zeros and ones. I guess with a working drive you can at least write as many test patterns as you want until you maybe figure it out.
Re:The long road to recover Frogger 2 source from tape drives by jandrese on Wednesday May 24, 2023 @04:03PM (#36063216)
At the very least the drive needs to be able to lock onto the signal. It's probably encoded in a helix on the drive and if the head isn't synchronized properly you won't get anything useful, even with a high sampling rate.
Re:The long road to recover Frogger 2 source from tape drives by Clamchop on Wednesday May 24, 2023 @08:20PM (#36065699)
I would be surprised if it used helical recording. Data tape recorders rarely do because it's much more complex, increases tape wear, and the use cases don't usually demand that kind of linear bandwidth.
Re:The long road to recover Frogger 2 source from tape drives by jandrese on Wednesday May 24, 2023 @09:56PM (#36066278)
Wasn't the whole selling point of these drives that they were able to encode more on the tape than their competitors? I figure that must include some clever tricks.
Re:The long road to recover Frogger 2 source from tape drives by userbinator on Thursday May 25, 2023 @12:17AM (#36067018)
The data format is documented at a high level here:

https://github.com/Kneesnap/onstream-data-recovery/blob/main...

It's a linear, 192-track format that's read 8 tracks at a time. The other files in that repo are also worth reading.

Re:The long road to recover Frogger 2 source from tape drives by bombcar on Wednesday May 24, 2023 @04:40PM (#36063598)
Yes. There’s some guy on YouTube who does stuff like that (he reverse engineered the audio recordings from a 747 tape array) but it can be quite complicated.
Re:The long road to recover Frogger 2 source from tape drives by Nextgrid on Wednesday May 24, 2023 @06:05PM (#36064446)
Would you have a link by any chance? Thanks!
Re:The long road to recover Frogger 2 source from tape drives by bombcar on Wednesday May 24, 2023 @07:48PM (#36065420)
https://youtu.be/MU02pQe3E5Q Is the one I’m thinking of, digital would require more work
Re:The long road to recover Frogger 2 source from tape drives by EvanAnderson on Wednesday May 24, 2023 @05:25PM (#36064056)
For anybody who is into this this is a a good excuse to share a presentation from Vintage Computer Fest West 2020 re: magnetic tape restoration: https://www.youtube.com/watch?v=sKvwjYwvN2U

The presentation explores using software-defined signal processing analyze a digitized version of the analog signal generated from the flux transitions. It's basically moving the digital portion of the tape drive into software (a lot like software-defined radio). This is also very similar to efforts in floppy disk preservation. Floppies are amazingly like tape drives, just with tiny circular tapes.

Re:The long road to recover Frogger 2 source from tape drives by Kneesnap on Thursday May 25, 2023 @03:26AM (#36067963)
OP here! Yes I'd highly recommend this video, I stumbled across it early on when trying to familiarize myself with what the options were-- and it's a good video!
Re:The long road to recover Frogger 2 source from tape drives by dpratt on Wednesday May 24, 2023 @06:35PM (#36064709)
At the very least, and the cost for this perhaps would be prohibitive, but some mechanism to duplicate the raw flux off the tape onto another tape in an identical format, a backup of the backup. This would allow for attempts to read the data that may be potentially destructive to the media (for example, breaking the tape accidentally) and not lose the original signal.