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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 24th Jul 2020, 5:42 pm   #21
Paul Stenning
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Default Re: Hard drive erasing?

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Originally Posted by TonyDuell View Post
I am rather worried about the 'small old drives are worthless' attitude here. Many drive with 'legacy' interfaces are getting very hard to find now (even the once-common ST412 interface (aka ST506, MFM, etc) is rare now). You can't always replace the interface card and use a SATA drive (try that on a PERQ, PDP11, Whitechapel MG1, etc and you have many months of work ahead of you). You don't say 'Oh, the UL41 output valve is worthless, a KT88 will give you a lot more power' do you?
The "small drives are worthless" attitude applies to SATA and IDE disks which are plentiful and will continue to be probably for decades. An IT recycling charity that I have sent quite a lot of kit to for clients just degauss and shred 250GB and smaller IDE and SATA disks, even though most are probably working fine.

A good indication is to look on eBay and see how many of them are being offered for sale, and what sort of prices the sold ones are fetching. Anything that is on there in large numbers and selling for under a tenner is not worth wasting time with. Unless someone wants to store then for 10-20 years and see if they are worth anything then?

However older MFM etc interface drives and indeed any where the capacity is shown in Megabytes rather than Gigabytes are definitely not in that category.

With the drives being discussed here it may be worth checking how common they are now before reaching for the hammer.
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Old 24th Jul 2020, 6:05 pm   #22
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Default Re: Hard drive erasing?

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Originally Posted by Paul Stenning View Post
However older MFM etc interface drives and indeed any where the capacity is shown in Megabytes rather than Gigabytes are definitely not in that category.

With the drives being discussed here it may be worth checking how common they are now before reaching for the hammer.
Yes, I once had a 5 megabyte eight-inch drive with a SASI interface that used to dim the house lights at switch on. Unfortunately scrapped 30 years ago....
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Old 24th Jul 2020, 6:25 pm   #23
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Default Re: Hard drive erasing?

At one time, I worked for a company with some customers who would not let failed hard drives off their site unless they had been turned into fine granules. They wouldn't let DRAM boards off their site either, DRAMS don't guarantee to forget everything after the refresh time is exceeded, the repair person could unplug them from the computer and surreptitiously quickly plug them into something else to preserve the contents.

To avoid scrapping major bits of the hardware, I once had to explain that I would stake my life that a large board of ECL logic containing ECL SRAMs would forget everything pretty quickly once the power was off. Quite different to the earlier core stores, which had significant long term memory of you talked to them nicely - the core was definitely not allowed off site.

The concern was that baddies who knew where the parts came from would go to considerably lengths, and plenty of time and money, to extract fragments of information. With the business some of them were in, they were right to be paranoid, but I wouldn't think such precautions were needed for folk on here with old household computers.

Would reformatting the drive be enough to hide such things as bank passwords from almost anyone except highly specialized agencies?

Stuart
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Old 24th Jul 2020, 6:37 pm   #24
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Default Re: Hard drive erasing?

No. You need to overwrite the data. Reversing a disk format is relatively easy if somebody wants to do it - you don't need to be James Bond, or even a data recovery specialist.

Overwriting the disk is very straightforward though - it just takes a while with a big drive as every disk block needs to be rewritten.
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Old 24th Jul 2020, 7:10 pm   #25
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Default Re: Hard drive erasing?

I have just always used a PC and Darik's? Boot And Nuke (DBAN), will run even off a floppy.
Choose a method that's thorough enough for the sensitivity of the data that's on it and let it get to work.

https://dban.org/
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Old 25th Jul 2020, 9:19 am   #26
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Default Re: Hard drive erasing?

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You do need to overwrite the disk if you're concerned about the contents, as it's relatively easy to recover files from a drive if they've just been 'deleted', or even if the partition table has been overwritten.

I agree that there's no need for the really paranoid actions though - overwriting the drive with dozens of passes, that sort of thing. There's no documented example of any data recovery organisation recovering real world data from a drive that has been overwritten with a single pass, even in laboratory conditions, and any commercial company would certainly publicise it if they could do it. Spooks like GCHQ and the NSA like to imply that they can do it, but that's really just psychological warfare.
Hmm - recall from my MOD days that when a 'secret' drive was take out of service we had to break them apart and slice through the individual platters before they went into the skip. (very easy to nick one's fingers on the sharp bits!) It was alleged that 'erased' data might still be read by aligning the head slightly offset to the original track. Never seen it done though.
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Old 25th Jul 2020, 10:04 am   #27
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Default Re: Hard drive erasing?

Yes, this is a theoretical technique which has been demonstrated in the lab with very small amounts of data. A custom firmware board is used which allows the position of the heads to be deliberately slightly misaligned. The resultant signal is then subjected to lots of digital processing which in some cases can decode the overwritten data, though the error rate is high and the techniques have more in common with statistical cryptography than normal data recovery.

Nobody has ever publicly demonstrated recovering a complete overwritten real world disk using this technique.

People like the military and GCHQ have to consider attacks by state actors with unlimited resources, so adopt an extremely conservative approach. The 'bash it with a hammer' method advocated in this thread wouldn't be good enough in these circumstances, as data can be recovered from physically damaged platters given sufficiently advanced facilities.
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Old 25th Jul 2020, 10:33 am   #28
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Default Re: Hard drive erasing?

A friend of mine gives his scrap HDDs a "Makita Format" - drilling a dozen holes right through the entire thing - PCB, chassis, platters, cover - with a 10mm drill.

I have been known to lob smaller HDDs into my woodstove, where they are reduced to grey 'slag' in an hour or two.
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Old 25th Jul 2020, 11:36 am   #29
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Default Re: Hard drive erasing?

If the machines won't boot up then I don't see any easy way to erase them in situ. Boring holes in them is as good a way as any to render them unreadable. However if you remove them then why destroy them? A buyer won't be interested in a destroyed drive so you'll be selling the Macs without drives anyway. Just keep the drives somewhere. You can always connect them to an adapter which converts them to a USB drive. Then you can easily plug them into any PC you want if you suddenly realise that you need the data on them after all, or run some erasing software (on Linux dd works very well).
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Old 25th Jul 2020, 1:35 pm   #30
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Default Re: Hard drive erasing?

In the dim and distant past I was involved with Mil spec. laptops, some had a marker to show where to aim a gun to destroy the HDD. Effective but unlikely to be available to most of forum members.
 
Old 25th Jul 2020, 1:47 pm   #31
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Default Re: Hard drive erasing?

That would make sense for laptops used in combat zones, where withdrawing forces might need to destroy data quickly without any special skills. You don't want to mess about booting Linux from a CD when the Islamic State fighters are coming over the hill.
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Old 25th Jul 2020, 1:47 pm   #32
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Default Re: Hard drive erasing?

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In the dim and distant past I was involved with Mil spec. laptops, some had a marker to show where to aim a gun to destroy the HDD. Effective but unlikely to be available to most of forum members.
Rather than risk arrest, repurpose: https://www.instructables.com/id/Musical-Hard-Drives/
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Old 25th Jul 2020, 2:04 pm   #33
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Default Re: Hard drive erasing?

Whenever I've decided to scrap an HDD, it's reach for the set of Torx drivers, dismantle the drive, remove the platters and using a power saw, cutting them in half. Often I keep the magnets. They're useful for attaching 'post-it' type notes on the 'fridge door: "The milk lives in here!" etc.

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