4 ms·
IIRC correctly, unlike HDDs, (audio) CD players change their rotation speed to match the data density, because they need the data at a constant bit rate. So it
by codeflo 7y ago
IIRC correctly, unlike HDDs, (audio) CD players change their rotation speed to match the data density, because they need the data at a constant bit rate. So it wouldn’t matter whether the data starts inside or outside. I think your argument about physical robustness is very plausible.
Additionally, starting from the inside allowed for physically smaller disc formats without any special software support: https://en.m.wikipedia.org/wiki/Mini_CD https://en.m.wikipedia.org/wiki/Mini_CD
I don’t know for sure if that possibility was part of the original design. But it must have been introduced somewhat early, given that every CD player tray I’ve ever seen has that extra ridge to hold the smaller discs in place.
- monocasa 7y agoDepends on the drive. Game consoles and computers tend to have CAV drives. Early 1x speed 'media player' drives tend to be CLV though yeah because they're working at the margins of acceptable bitrate as it is with real time constraints.
- dfox 7y agoCDDA is purely CAV optical medium.
- nezgar 7y agoCDDA is CLV. https://en.m.wikipedia.org/wiki/Constant_linear_velocity https://en.m.wikipedia.org/wiki/Constant_linear_velocity CD ROM drives may spin CD's with CAV, but if so the data rate changes, increasing steadily towards the outer edge of the disc.
- throwaway3563 7y agoI suspect CD ROMs used CAV (in contrast to audio CDs which used CLV) because the processors (perhaps originally based off audio processors) could intially only deal with a fixed data rate, and with CLV + random access, the drive would have to spin up and down repeatedly according to where on the disk the laser had seeked to, which would have a large impact on random access times. As the speed of drives got faster and faster (up to 52x) that problem wouldve been exacerbated too.
- Scoundreller 7y agoIt’s still dumb from a power utilization standpoint to go inside to outside when that means you always have to spin the fastest for the always present data and slow down as you go.