Diablo Drive Appears To Be Cursed

[CuriousMarc] didn’t think it would be a big deal when a former Xerox employee sent him an Alto Diablo drive for service. Turns out the drive was cursed — it would destroy everything it touched including a set of heads and an alignment cartridge. [Marc] and a partner spent two months trying to get the drive operable and the video of their process is pretty interesting.

We were interested in the troubleshooting, but we were really envious of their lab, full of HP workstations, an IBM mainframe, and even a Selectric. We kept having to rewind the video because we had tuned out while we were staring at some of the equipment in the background.

The guys got a lot of practice aligning the heads on the drive. Because the crashed head was bent, it actually dug into the alignment cartridge so on subsequent attempts they had to manually load the disk past the damage. They learned to leave the disk a little out of alignment because tightening the assembly will move it a little bit. If you were already aligned, the heads would be off after you did the tightening.

They used a custom FPGA-based tester that [Carl] developed after reverse engineering the disk format. It is amazing to watch the big drive in action and realize that a standard cartridge for this machine was 2.5 megabytes. There was another controller and disk system called the Trident that would get you a whopping 80 megabytes, but we don’t think this is one of those.

Did they succeed in exorcising whatever demons lived in the drive? Watch the video and find out. Even if you never have to fix a Diablo drive yourself, you’ll be entertained. Especially when they work out how to do a current adjustment on the drive by simulating the circuit in Spice.

We’ve seen a lot about the Alto which is surprising considering how few of them were built. We’ve seen a restoration and even an odd use for a light bulb related to the Alto’s CRT.

11 thoughts on “Diablo Drive Appears To Be Cursed

  1. Gone are the day when drives were expensive enough that it was worth trying to fix everything. Today we just toss dead hard drives and buy a new one for about $100 DVD or BD-ROM drive having some trouble? Throw it away and get a new one for even less. We’re long past needing disk drive in any format.

    1. A lot lesser, but more common, computers would now be kept going with workarounds. So someone would build an IDE adapter and software for a Radio Shack Color Computer. Or connect a memory card to some other computer. Things like that, giving much better capacity at lower cost to replace some “obsolete” storage method.

      But the Alto is a classic and even legendary computer, the value in part being that it anticipated the future, rather than being a really great computer. I’m sure someone could emulate the Alto with a Raspberry Pi, but it wouldn’t be the same thing. They are also so rare that some extra work might be warranted.

      You don’t modify classic and rare cars, you track down needed parts, or machine new replacement parts. And the same with something like the Alto. The massive drive was part of it all, and the expense and size of the drive, versus the low capacity, gives insight into the Alto and computing at the time.

      That said, surely someone’s figured out how to add some current device to provide more capacity and reliability at way lower cost.


      1. ‘You don’t modify classic and rare cars’ too right, except now we have all those rat rod monkeys. It is perfectly cool to do those things with common rotboxes, but please don’t go hurting things that there was only ever 10 of, or the glorious classic designs (I’m looking at that person that put chevy sports car underguts in and chopped a defender to fit)

        1. ‘You don’t modify classic and rare cars’

          Well, thats just your opinion.. man! lol

          Why not, even if there were only 10 of them it is still just a thing and as we go and re-write history every day who are you to say that one object is more important than the next. Take confederate statues for example, from what i hear there are a bunch of people really interested in destroying them, why not instead move them and keep them intact for history’s sake? Because its a battle of opinions and nothing more, some people find them offensive, some find them patriotic, some want to keep them for history’s sake, some want to re-use the raw materials for something else. The difference with cars and computer parts is that one individual owns these things and really it is their decision to do what ever they want with it. Who are you to tell them what to do with it? would you be ok with a manufacturer telling you the only ways that you could use their tools?

          The point i am trying to make is that it is never ok to tell someone what they can or cant do with their property no matter what your personal feelings are about said object because you wouldn’t like it if the shoe was on the other foot.

          full disclaimer: i am a person that modifies cars to their own liking, often going against what other people think should be done because i build them for myself and to my own personal vision. I can tell you that it doesn’t matter which car you modify, there will always be some subset of society that thinks that you shouldn’t be modifying it in the way that you are and that there is no general consensus in any aspect.

  2. Tridents were 80 mb or 300mb. Spent many hours aligning heads on those guys in the field. I think they were Century Data System drives. Can’t remember but probably have manuals in the garage.

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