Messages in this thread | | | Date | Sun, 07 Feb 1999 10:44:14 -0500 | From | Mark Lord <> | Subject | Re: SONY or CD-ROM lying about speed? |
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Thierry Danis wrote: > > On Sat, Feb 06, 1999 at 04:37:34PM +0100, Jon K Hellan wrote: > > I have a SONY 32x CD-ROM CDU771. However, Linux reports it as 14 > > speed. Apparently, FreeBSD does the same.
The PIDENTIFY_DEVICE command is sent to the drive, and one of the data fields returned is "drive maxspeed" which in this case the drive sets to "14 x 176KB/sec" (176KB/sec = 1X or "original" CD speed).
Linux just displays what the drive told it.
> I've seen the same. Running a 'dd' over a complete CDROM > gives me a transfer rate around 2100 KB/s, which is x14. > I have a CD-ROM CDU701.
Note that the "maxspeed" only applies to a small zone on the outer tracks, which is why cdroms are now advertised as "up to 32x" rather than "32x". The *average* over the whole drive will be much lower than the maxspeed. -- mlord@pobox.com
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