hard disks

Up until a couple of weeks ago I owned an ancient (12 year old) computer. I’d been storing the thing for years in hopes that I’d find the space to set it up (I’m actually a pack rat–I need these excuses). Well the apartment seems to be getting smaller with all this stuff, so I decided to give the computer the old heave ho–after I take it apart.

So now I’m sitting here looking at thse two metal hard disks, and I’m wondering what they’re made of. They’re maybe 2/3 to 3/4 the diameter of a compact disc and roughly the same thickness of a CD, but the metal is quite stiff; it barely bends. Any idea what they were making hard disks out of back then? FWIW, the manufacturer was CompuAdd, IIRC.

Aluminum or glass substrates with various coatings. Put on your safety glasses and whack one of them. If it shatters, it was glass.

Try howthingswork.com might have some fun info. Im pretty sure they were copper plates.