i have an old zenith "ez pc" (they got there before eyetech!) it has a 30mb drive. it has 520k of ram. there was an upgrade plug in to 640k!!! it probably cost the earth. i had to partition around a serious problem on the disk. i hardly use it as it's black and white. but i love the sound it makes on boot up. lots of lovely beeps.
i keep my 2nd hard drives (for backup) or with a different os on in removeable drive bays so the drives are off while i use the 1st disk. they have lasted a good time longer by not being used. i use a good amount of ram where possible so they are not worn out with virtual mem swapping. but...
i bought a 250gb new sealed hd and it was damaged after a few uses. and had to send it back. software that comes on floppy can usually repair the drive by bad block swapping. i rescued a 60gb drive of mine that i think had been dropped like this! and it works fine.
i just found "autopark prefs" glad to see i can set any amiga drive to switch off with an amiga and save there life a bit. i've set them for 5 minutes.
