Re: Origin of "partition" in storage devices

[Paul Koning via cctalk]

> On Feb 1, 2022, at 12:16 PM, Mike Katz via cctalk <cctalk@classiccmp.org> 
> wrote:
> 
> In the rotating drive world there is constant linear velocity (CLV) and 
> constant angular velocity (CAV) drives.
> 
> On CLV drives the speed of rotation would vary based on the track (slower in 
> the inner tracks and faster on the outer tracks).  This meant that the data 
> rate and number of bits/track remained constant.

Slower on the outer tracks, I believe.  CDs work this way.

> On CAV drives the rotational speed of the drive doesn't change, this means 
> that the data rate and number of bits/track changes depending on the track.

It means that only if the sector count changes.  That's true for modern drives 
and for the CDC 6603; it wasn't true for quite a while.  A lot of "classic" 
disk drives have constant sector counts.  So, for example, an RP06 is a CAV 
drive and its transfer rate is independent of cylinder number since the sector 
count per track is constant.

I think hard drives are CAV as a rule because changing the spin rate as part of 
a seek takes too long.

        paul