I'm weeding out my basement store of old computer paraphernalia. Finally!
Once I thought I'd lay may hands on an old PC, a coax ethernet card and coax cables so I could set up a Novell network, the way it was in my heyday. I'll leave them in my store even now, you never know, BUT I suspect this is not going to happen, there are always other projects with a higher priority to finish. Some never seem to finish.
I decided to scrap some disks but since I just can't force me to throw things away without recycling them in the futile hope they will be used in some later (nutty) project that never will be realized. My problem.
Well, digging around I came across my old Psion LZ64. Yay!
Since I had a new 9V battery I installed it to see if it (Psion) still worked. I did!
When I worked for Data General (1978 - 1994) it was my favorite piece of equipment. It had a calendar! I forget meetings (because I hate them) but here was a friend that could beep, in time for me to go to the damned meetings. It saved me a lot of problems! Besides, I had a complete list of all spare numbers in it. Very useful when ordering stuff from the main office for the next day. It was very usual to go to a customer to search for the reason of failure, order spares to the next day, getting them from the railroad express outlet in the early morning and then go back to the customer and fix the problem before lunch, fingers crossed.
It was programmable (OPL, Organizer Programming Language), I liked that.
So here I am, my Psion working and I decided to look for information of it on the Internet, just for the fun of it. I found it.
In the wayback machine:
https://web.archive.org/web/19990225155521/http://www.org2.com/
In wikipedia:
https://en.wikipedia.org/wiki/Psion_Organiser
The most interesting one, Jaap Scherphuis homepage for Psion, You can read about him in the Wikipedia post:
https://www.jaapsch.net/psion/manxp.htm
This was a fun trip, way back!
OK, back to the scrap yard. I disassembled some old ATA disks, saving their head assemblies, spindle motors and Niobium magnets. I have no rational reason for this behavior, it seems to be a personality disorder.
Especially the motors interested me. I had no clear idea about how they work. I thought this could be a tough thing to search for, things like that are sometimes buried inside the corporations for good. I did find some interesting info though and, not surprisingly, I found in a post in Russia! The were trying to use old disks as emery machines for tools! Hilarious invention! The guy doing the research for how this could be realized, is of the right mettle though. He knew what he was doing:
https://gtshina.ru/en/avtozvuk/kak-podklyuchit-motor-ot-vinchestera-pomogi-s-zapuskom-dvigatelya-ot-zhestkogo/
The motors are build as three phase, Y- or D-connected (tree or four wires) and if you feed them three square waves, shifted 120° it will work. Nice and interesting.
As a final of this post, an image showing the size of the read/write heads and actuator assembly second on hard drive I worked on in 1978 (the first one aas a Diablo 2.4Mb :) compared to what they looked like 1995 or thereabout. The old disk was a 10Mb dual platter (one fixed [meaning you had to have a screwdriver on your toolbox], the other swappable), DG model number 6045.
I have lost count of the number of times i repaired these. They were good drives but we had so many of them in the field. Sometimes they landed with their heads on the platter. The platter was destroyed, naturally (the surface looked like the magnetic material on recorder tape at the time, rust-colored), but after changing the platter, normally you could scrape off the deposit from the platter off the heads with a pen knife. Then it was "go" and no problems. Cheaper for the customer! Rugged machine!
https://www.nobelprize.org/uploads/2018/06/grunberg_lecture.pdf
This Nobel price guy wasn't the first (or only) at the time. There was another guy that invented the same thing. One of these two got his patent earlier and won the money for it (the terabyte disks arrived as a consequence of this), The other guy ( I think it was the Nobel Prize winner) had to be content with the honor.
Seeing this hefty magnetic actuator for the 10 Mb disks, just imagine the one I have in my garage that comes from the 96 and 192Mb drives. I hesitate when I have to lift it. It's enormously heavy. Hitherto my only use have been using it to weight down parquet boards in our living room after a leak from a water filled radiator. Good enough, I was happy to have it at that time.
A fun thing with these is that if you short circuit the coil on these (white to black lead) and then manually push it in either direction it will generate enough EMF ( https://en.wikipedia.org/wiki/Electromotive_force ) to continue driving by itself in in the same direction. It gives you a funny feeling, like a long, soft and damped stop instead of just a immediate stop, caused by friction.
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