Rise and fall time of TI 'F' family

Armco Steel built a computer controlled hot strip in Middletown Ohio. It opened in the early '60s and was controlled by a computer supplied by Westinghouse. It had a 36" 10 MB hard drive that took over five minutes to come up to full speed. It ran on 208, three phase. The disk drive motor was 2 HP. The system was in use until the mid '80s when they replaced it after it started causing problems, and they had no real source of spare parts.

Remember those Phoenix 15" drives with the removable pack that went in over the fixed disks? Had to be run on purge about an hour before you

4" voice coil and the head carriage on ball bearing rollers - great to watch doing a butterfly test.

Puny by comparison with your beast, though, only a 1/4 HP motor

About 300MB, IIRC.

Some of those were still in use in the mid -1990s

Remember them? I scrapped truckloads of the old 20/20 drives with 20 MB fixed and 20 MB removable. I still have a big box of the magnetic couplings from the scrap disk packs. The magnet assembly is missing from the bearing, but I am building a wire measuring machine using an AC motor with the magnet for the supply reel, and a belt driven DC motor to drive the take up spindle. A controlled DC current to the AC motor will control the tension, or brake the reel if the wire breaks or runs out.

The worst design I saw was an early Burroughs computer that was built with what looked like a clear vinyl VCR cover that was placed over the open drive. I was surprised that the disks weren't gouged, but it had sat in storage long enough to have dust on both sides of the disk.