Path: cdrom.com!agate!howland.reston.ans.net!math.ohio-state.edu!jussieu.fr!centre.univ-orleans.fr!univ-lyon1.fr!swidir.switch.ch!newsfeed.ACO.net!Austria.EU.net!EU.net!uunet!ankh.iia.org!cyra From: cyra@iia.org (Andrew Cyr) Newsgroups: comp.sys.ibm.pc.hardware.cd-rom,alt.cd-rom Subject: Re: Too much data makes CD harder to read? Followup-To: comp.sys.ibm.pc.hardware.cd-rom,alt.cd-rom Date: 11 Aug 1994 12:53:55 GMT Organization: International Internet Association. Lines: 22 Message-ID: <32d713$8vn@ankh.iia.org> References: NNTP-Posting-Host: mary.iia.org X-Newsreader: TIN [version 1.2 PL2] Xref: cdrom.com comp.sys.ibm.pc.hardware.cd-rom:4259 alt.cd-rom:7917 David Elliott (dce@netcom.com) wrote: : In article hoxley@max.tiac.net writes: : > There are two formats for CD-R blanks, 62 and 74 minute. : >The 74s have more closely spaced "grooves" than the 62s. : >Thus a marginal CD-ROM drive could have problems with a 74. : According to Ken Pohlmann in "The Compact Disc Handbook", the : difference is the motor speed, not "groove spacing". In his words: : Although the CLV [Constant Linear Velocity] of any particular : compact disc is fixed, the CLVs used on different discs can : range from 1.2 to 1.4 meters/second. In general, discs with : playing times of less than 60 minutes are recorded at 1.4 : meters/second, while discs with longer playing times use a : slower velocity, to a minimum of 1.2 meters/second. : Thus, the marginality of the CD-ROM drive has nothing to do with the : inability to focus on the groove, but with the inability to get the : motor speed down low enough. In other words, the 31A has a cheap : motor. : -- : David Elliott - dce@netcom.com