| Field |
| Computer Science |
| Went Obsolete |
| 1980s, depending on the organization |
| Made Obsolete By |
| Hard disk "packs" and disk drives became packaged as a single unit, except in cases like floppy and Zip drive (which required less skill to insert/remove) |
| Knowledge Assumed |
| What does the reader need to know to use this guide? |
| When useful |
| There are undoubtedly still some old systems (typically for things like process control and military systems that change slowly) that use removable disks. |
These instructions pertain to the disk drives typically used in the 1970s and 1980s, which were measured in the megabytes (anywhere from 5 to 300 - beyond about 300, combined drive/pack became common).
A disk drive is the hardware that contains a motor to spin the disk, "heads" that read and write data from the disk, electronics to encode/interpret the magnetic information from the disk, etc. The disk pack itself is a series of platters, typically a half inch thick. The number of platters differed from one type to another, but the most common had eleven platters, and twenty heads (the top of the top platter and the bottom of the bottom platter were unused; between each platter there were two heads, one facing up and one facing down). When not in use, the disk pack is stored with a smoked plastic cover that screws onto the top, and a (usually) black plastic bottom cover, thus keeping dust out of the pack while it's stored on a shelf. The top has a built-in handle in the center.
Hard disks are top-mounted, like a (traditional) washing machine, and were typically a similar size to a washing machine. Sometimes they were mounted in drawers within a rack, so the entire unit would slide forward.
Disk packs weigh in the range of 10-20 pounds, depending on the number of platters, etc.
To insert a disk pack into the disk drive, you typically squeeze a lever or slide a cover to open the door. Assuming the drive is empty (and if not, see below for removal), holding the disk pack by the top handle, use your other hand to remove the bottom protective cover by squeezing in the center or unscrewing it. Gently lower the pack into the well in the center of the drive, centering it. Turn the handle counterclockwise until it stops turning easily. Do not overtighten, or you can damage the pack and/or drive. Pull up on the cover (which will release itself from the drive when sufficiently tight), and put it on the base (removed earlier). Close the door of the drive, and push the drawer back in if it's rack mounted. Push the start button. The cover and base are generally kept on a shelf near the drive.
To remove a disk pack from the disk drive, push the stop button. Wait for the drive to stop turning - there's usually an audible "click". [If you're brave, you can open the cover while the disk is still turning and gently touch the center part - not the magnetic part - slow it down. Don't stop it to abruptly, or you'll break the pack. Disk drives of this generation spin at 3600 RPM ] When the disk stops turning, open the drive door. Remove the cover from the base (ensuring that you've got the right cover - they are usually labeled with a sticky label so you can find the pack again later). Gently lower the cover onto the pack, and turn the cover clockwise using the handle until it won't turn easily. Gently pull up (it may require a slight tug). Lower the pack and cover onto the base, and latch it to the bottom (usually by squeezing the center of the base). Put it on the proper shelf, and close the drive door.
Other references
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