"R.S." <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... > McKown, John wrote: > >> -----Original Message----- > >> From: IBM Mainframe Discussion List > >> [mailto:[EMAIL PROTECTED] On Behalf Of Paul Gilmartin > >> Sent: Thursday, July 12, 2007 1:57 PM > >> To: IBM-MAIN@BAMA.UA.EDU > >> Subject: Re: Track size and maximum single volume data set size > >> > >> > >> On Thu, 12 Jul 2007 14:34:17 -0400, J R wrote: > >> > >>> Well, I was always aware of the trade-offs, i.e. bit density > >>> at the center v. bit density at the outside, but I wasn't > >>> aware that anything was ever done about it with variable > >>> data rates, etc. > >>> > >> CD players, like the original Macintosh 390 K floppy disks, > >> vary the angular velocity inversely with cylinder radius > >> in order to have both uniform linear density and uniform > >> data transfer rate. > >> > >> -- gil > > > > Right. Disk drives are generally CAV - Constant Angular Velocity - aka > > the RPMs never change (not, not Redhat Package Manager files for you > > Linux people <grin>). Optical drives (CD, DVD?) seem to be CLV - > > Constant Linear Velocity. > > No more. It is true for audio equipment, it WAS true for early CD-ROM drives. > CLV was the most limiting factor for "speeding up" CD drives. > Since 8x, or 10x drives CLV is no longer used. Current CD-ROM drives use ZCAV - Zone CAV. That's why you have 52x *max*. Real speed depends on zone. > > > -- > Radoslaw Skorupka > Lodz, Poland > >
DVD-R(W) use CLV, DVD+R(W) use CAV. That is why a DVD-* only supporting devices can partially read a DVD-+*, but after a certain part, the Linear Velocity becomes to large, due to the CAV. Kees. ********************************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 ********************************************************************** ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
