Following on from the first attempt to recover data from 30 year old Magnetic Scrolls TK50 backup tapes, it's been a roller-coaster ride, so I thought I'd post an update;
Rob Jarratt has been doing an absolutely amazing job at persuading these old tapes to read again - and it's not easy. The picture above shows his TK50Z tape drive dismantled.
Back in the 80's and 90's, tape based backup systems were very popular due to their relatively large capacity and the affordable cost of tapes. And you'd think that a backup onto a tape, kept quietly in a cupboard would be good for years and years, providing of course you could still get a drive to read it.
Well, finding a drive to read the format is one problem, but another is the so-called Sticky-shed syndrome. No, this has nothing to do with your broken shed door; turns out old tapes slowly absorb moisture over the years to the extent that they stick to the drive head rendering the tape unreadable. In some cases the binding glue holding the magnetic oxide to the plastic backing can break down leaving rusty particles on the guides and heads and generally all over your tape drive. Not good.
Quite a problem, requiring the drive to be dismantled and cleaned.
Bake Me a Tape
Turns out there could be a solution. You bake the tapes!
That's right! You can bake them in a domestic oven. It sounds totally crazy and insane. But the idea is that if you bake slowly and at a low temperature, you effectively dry out the tapes and they will read again.
So how slow and at what temperature? Well, no one seems to know for sure, and it must depend on the type of tape, it's age and how it's been kept.
Rob's been trying to find the right recipe. First he tried, on an old tape, baking at 50 degrees C for 5 hours. This was too hot and it might have ruined the tape (although it was a suspect tape in the first place so we don't know for sure if the baking damaged it).
Then Rob tried baking another tape at 40C for 5 hours. This nearly worked as the tape read a bit, but then stuck to the drive head, but before the baking the tape wouldn't read at all.
On the right track!
Next up, bake at 40C for 8 hours. This time, Rob managed to recover a directory listing before the tape stuck again.
So Rob baked the same tape at a little higher temperature, at 45C for 8 hours - which worked! This time he managed to restore some actual files and the tape did not stick at all!
Unfortunately, this particular tape did not contain any of the Magnetic Scrolls original game source code we want. But, we expected that, because the tape labels give us some indication of what might be on them. We deliberately chose a tape to experiment with that was least likely to contain vital backups. Although we don't really know for sure what's exactly on each tape.
So now it's time to try baking a tape more likely to have the game sources. I just hope we don't end up with game sauces !!
Here's Rob's system set up:
DEC Station 2100 with TK50Z Drive
All source code recovered will be made public.
Wish us luck!