🚀 go-pugleaf

In article <1993Jan11.220701.718@njitgw.njit.edu> dic5340@hertz.njit.edu (David Charlap) writes:
>The next question is that of capacity.  If the MD player is at CD
>quality, it will record at about 44,000 16-bit samples per second.  I
>believe the time-limit of a MD is 74 minutes.  This yields 44,000 x 74
>x 60 = 195360000 or 186MW or 372MB.  This is unformatted, of course.

I *believe* that there is somewhere between 25% and 40% data redundancy
on audio CD's (to provide for error correction).  Also, you forgot that
there are 2 audio samples @ 44.1 khz, but I don't know if they are stored
at the full 16 bits or 14 bits per channel.  So there is more like 600 to
650 mb (at least) of possible data storage on a conventional audio CD,
which is also the figure quoted in CD-ROM advertisments.

>Now, comes the issue of speed.  Since the unit is meant to record live
>audio, it must be able to record at least 44,000 16-bit samples per
>second.  This comes up to 88,000 bytes per second, or 85K per second.
>A slow transfer rate, when compared to hard drives, but fast when
>compared to floppies.  As for seek time, who knows.  That much can't
>be derived from it's performance as an audio player.

The CD-rom drives that have been on the market since day one had a transfer
rate of 150k/sec, which is what you would expect out of an audio CD-player
(remember to double your figure above).  There have been new drives available
for some months now that are "double speed", ie they can transfer at 300 k/sec.
The specs (From IBM's Technical reference manual for their original PC) says
that the original 360k low density full-height 5.25" drives had a transfer rate
of 250k BITS per second (32000 bytes/sec).  A high-density drive is probably
doing 40-50k/sec.  The typical 20 MB hard drive in a 10 mhz PC-XT can easily do
150k/sec, and a typical 40 MB drive in a 10 or 12 mhz PC-AT can easily do
300 k/sec, if not 350 or 400 k/sec.