lauren@RAND-UNIX.ARPA (07/20/85)
If you keep all your desired data in a narrower band, you can of course keep the seek time farther down. Transfer rate from the discs isn't terribly impressive, however. One important point to keep in mind is that current relatively slow CD players aren't designed for extremely high duty cycles. If you design players that will stand up better and work faster, the price will be somewhat higher, and in fact will start to intersect (if they haven't already) with magnetic disk media of similar storage capacity (when looking at a 10 Mbyte band on a CD, for example). At that point, there's little point to spending the money on the CD player instead of the magnetic media, since you're going to need the magnetic disk also in any case. That is, unless the mass archival capabilities of the CD are of particular use in your application. CD's are really optimal for mass data that needs to be read occasionally in a comparatively non-rigorous fashion (from a time and duty-cycle standpoint). Anything else is starting to push the technology in directions that become decreasingly cost effective when compared with magnetic media, particularly given the still rapidly falling costs of magnetic media. --Lauren--
caf@omen.UUCP (Chuck Forsberg WA7KGX) (07/24/85)
Another factor slowing CD access time: the disk rotates at 500 RPM on the inside tracks and slows to 200 RPM at the outside. This could be the real limiting factor in access time as the head assembly could probabaly be made to move in well under one second. Laser videodisc players are available with a 1 secone access time (CAV discs), this would correspond to 1/2 second if things were reduced directly in proportion to the amount of head movement. -- Chuck Forsberg WA7KGX ...!tektronix!reed!omen!caf CIS:70715,131 Omen Technology Inc 17505-V NW Sauvie Island Road Portland OR 97231 Voice: 503-621-3406 Modem: 503-621-3746 (Hit CR's for speed detect) Home of Professional-YAM, the most powerful COMM program for the IBM PC