how fast were drum memories?

[Ali]

> Looking at modern hard disks, I'm unconvinced we could even mass-
> produce
> something like that today.
> 
> A 40mm radius is comparable to a 3.5" disk, which are generally 5,400-
> 7,200
> RPM. 15,000 RPM is the fastest available, but those tend to be low-
> capacity and
> expensive, and are often 2.5" drives with a huge heatsink. 

I am not sure if that hold true. 15K drives have been around at least for 20
years (unless you are considering that part of today?). I was using Seagate
Cheetah SCSI drives in 9Gb and 18Gb capacities w/ 3.5" platters spinning at
15K RPM back in the 2000s.

They may not be terabyte HDD but 15K RPM was definitely not an issue.

-Ali