How easy to read/write data to this vintage HDD?

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nzoomed

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I was given this vintage 14 inch hard drive from the early 1980s a couple of years ago.

I always wanted to make it into a static display, so got a case made for it.

Now after mounting it in the case, the curiosity got the better of me, and thought it would be pretty cool to add a motor to it and see it spin up. I also got the heads to move by applying 12V to the voice coil.

It then had me wondering how easy it would be simply as an experiment for curiosity sake to make some sort of controller with an arduino or something that could read and write to the disk.

I believe it is 40MB capacity, but have no idea what RPM it was, or how many cylinders, sectors etc it has, nor the encoding method.

It's a tecstor model 83"xxx" with the rest of the text missing on the damaged label

Don't know what voltage the heads need to write to the disk surface either.

None of this may even matter if something can be coded to read or write from scratch.

There are 6 heads and it has no heads on the 2 outside disk surfaces.

It's missing the original belt driven motor and whatever logic board it had.

It came out of its own unit the size of a washing machine and used to be in a hotels computer and removed from service a good 30 or more years ago.

The disks cover had been opened some years ago but always has been kept on, so is largely clean.

If its a waste of time, let me know, or else I will just try and find a way to put random pulses on the voice coil to show how it would have operated when going as a display.
 

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I won't say it's a waste of time - if you are interested enough to put time into investigating this old hard drive it's your choice. I'd find it interesting too and quite likely would play about and give it a go. In my case I'm always afraid of damaging something I can't easily replace. I don't even know whether the signals are digital or analogue and if the latter what kind of voltage and current. I actually thought the earlier hard drives used stepper motors for moving the heads and moved on to voice coils later. Maybe it varied from one designer or company to another.

If I was playing with an old hard drive my timidity might lead me to experiment with another old drive mechanism first. Anything you learn will still be useful and you won't risk damaging that nice old mechanism. (Do you think the label was accidentally damaged or might it be deliberate?) It may be worth looking online for pictures of old drives to get started on identifying it.

The physically largest hard drive I've ever dealt with was in Telex exchanges which my first employer made. They bought in a lot of the hardware including General Automation 16-bit minicomputers. We had a test area with a model exchange where I often worked, testing my software. It contained hard drives as wide as a 19" rack, almost touching the sides of the cabinet. I forget the make but I'm fairly sure they stored 256kb, so very much less capacity than any other I've dealt with since!
 
if you've had the platters exposed in normal non-dust-free air, you will have head crashes and likely won't be able to read anything from it... you've already moved the heads across the disk surfaces without the disks spinning, so the surfaces are damaged there as well.... the heads are supposed to ride on a cushion of air created by the disks spinning. when the drive is turned on or off, the heads are supposed to be in a "parked" position, usually an area near the disk hubs where there is no magnetic surface to ride on. once the disk gets up to operating speed, the heads can then be "unparked"... early disks had to have a program run to park the heads before powering down. later disks had built-in firmware that would park the heads if power failed or was turned off. if the heads weren't parked, once the cushion of air was lost as the disk spun down, the heads would dive into the surface, and strip the magnetic coating off the disk.
 
Early disk platters, like the ones I used (RK05,RP04 or RM02) were not hermetically sealed. In fact, platters of drives like the RP04 were fully exposed to local air after removing the carrier, until the lid of the drive unit was closed. The unit would then blow "clean air" thru and spin up the platters. After a while, the heads would load. Yes, we had head crashes, but not too often. It is correct that the platters should be spinning before the heads load, to provide the air cushion between the heads and the platters.
Early drives used "standard" modulation techniques, even older than MFM technology which was used on the first HDD for IBM PCs (5MB or 10MB).
Odds are high that those platters are not of any real use other than display purposes.
 
what seems to be missing from the drive is the interface electronics, head amplifiers and signal chain, head positioner servo electronics, AD/DA interfaces, etc.... without that, and a suitable data interface to a computer, this drive can only be used for show....
 
It is called a Winchester hard drive.
Hopefully, you will get some info by Googling.
 
I was surprised to see a voice coil on this too. I had a more later drive of the same size and it had a stepper motor controlling it.
It would be fun to experiment with but no doubt would be a huge task in getting something to write to the disk.
I have no idea on the flux required to write to the disk for example or how many tracks the disc has.
After taking a closer look at the drive, it actually has a pair of heads per each side of the disc, the bottom platter has only one head on one side.
the heads move half way across the disc, with each head per pair reading/writing one half.
Then there would be an area dedicated to servo information, etc.
The label is intact, but corroded over years so is missing some text, ill upload a photo shortly.

Yes I was unsure on what would be involved to rebuild this circuitry, if it was an experiment, I would have to come up with another way of encoding the data, but I have no idea what kind of signal would be used to position the heads, etc.

It probably is only good for show, but could be fun to hook up a motor and see it spin and connect some sort of oscillator to the voice coil to make it look like its working.


Ramussons said:
It is called a Winchester hard drive.
Hopefully, you will get some info by Googling.
Click to expand...
That term was essentially used in the early days for all fixed hard disks, even the 5.25 inch ones in a PC.


Edit:
Have attached photo
 

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Wow, 600W of power. As to how to write to the platter, I don't know. However, back in the 80's the need to protect data on tape resulting in us playing with various recording methods. Normally, any recordings are sine waves which result in cosine waves when played back. We played around with feeding a sawtooth wave to the head which would return a square wave on playback. If you tried to copy it it failed miserably. We had found a way to stop tapes being copied and speed up the transfer speed. Unfortunately, the duplication houses wanted nothing to do with it. It would have been interesting to see if such a method could increase the capacity of your drive. Unfortunately, as has been pointed out, you've probably ruined the platters just by spinning them up to speed without the park, unpark system.

Mike.
 
No one has mentioned the fact that these drives used MFM or RLL encoding... If MFM then access is more like accessing a floppy, without the driver card, it would be quite a challenge..

What would be cool, is to run it up ( with LED lighting ) and have a small SD underneath so it looks like its working!!
 
Probably, well 99.99% a waste of time trying to actually get some data transfer to/from the platers, the heads are super delicate. and has been said, need to fly over the disk surface so they are now probably damaged . actually to get a 'good' unit (similar tech) to seek the same track after a crash, was a big head ache (pun intended ) and required a pre recorded sync track . You could spin it up and possibly get the heads to move as a demo , but that's all..
 
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