dld@f.gp.cs.cmu.edu (David Detlefs) (10/21/88)
All this discussion about the NeXT machine and optical disk drives and DSP chips and all is very interesting, and makes for some interesting thinking. If there are any business ideas in the below, and you use them and make a million dollars, please send me a thousand or so. :-) 1. It ought to be possible to use your NeXT machine, with its big, moderately slow disc, as a CD player. You get a file of samples from somewhere, and run it through the audio out. Does the NeXT machine have a headphone jack? This should be so simple to do that it ought to take next to no processing time, so you should be able to listen to music stored on your computer while you use your computer. In the envisioned university network environment, there should be file servers that have collections of songs on them, which you download as needed (peak transfer rates for ethernet are a lot greater than the 80,000 bytes/sec or so required for CD-quality). The legal question then arises: if you buy a CD, does that give you the right to distribute the bits on a network? If the student doesn't walk away with a copy on his disk, then it's a lot like playing it out loud... 2. If you do have machines with optical disks at home, and you want to distribute large collections of data to these sites, then 9600 baud phone lines are obviously a little unsatisfactory. 10 Meg would take 10^7 * 8 / 10^5 = 800 seconds = 13 minutes, not counted extra error correction data sent. Has anyone thought of using cable TV for these types of one-way transfers? I know that my local cable company sells a service that allows PC's to tap into stock market quotes and weather and other one-way data like this. There are a lot of unused channels in most cable set-ups -- it could work something like You invoke a comand, your machine automatically calls the cable company's number, it gives you a channel number (and, probably, an encryption key), your machine listens to that TV channel as the cable company flashes the data by enough times for you to get it right, at which time you ackknowledge and hang up. You get billed. Where, you ask, did the cable company get the data in the first place? Well, I guess this would only be economical in areas where there are large organizations (like universities or Bell Labs or IBM) that have employees that would like to do this often. Then it might pay for them to establish a link between them and the cable headquarters. Maybe it's not practical, but it's an idea. 3. If I understand things correctly, a lot of the difficulty in making an optical (or magnetic) disk drive is in making the head lightweight, so the arm can accelerate quickly, cutting down on seek times. Well, if you only wanted sequential access, would that make things significantly cheaper? I'm envisioning an add-on optical drive that is logically like a tape drive, so that the head doesn't have to move much. You would use it pretty strictly as a backup device for home machines. Could this be cheap? Interesting stuff. I'm here at CMU where we're rediscovering the joys of centralized file systems, and all of a sudden here comes technological pressure forcing us back the other way... -- Dave Detlefs Any correlation between my employer's opinion Carnegie-Mellon CS and my own is statistical rather than causal, dld@cs.cmu.edu except in those cases where I have helped to form my employer's opinion. (Null disclaimer.)