Plextor CD writers

Chuck writes: The actual sectors on the CD-ROM are *always* really 2048-byte sectors. Setting a CD-ROM reader to 512 bytes/sector just splits each real sector into four. And many SCSI CD-ROM drives will gladly do this via a SCSI mode select command (though not all VAXen issue the command, nor do all drives pay attention to it!) and with some you can do it with physica jumpers instead (or also.) (Actually, I'm reluctant to call the information on the CD as "physical sectors" since really the data and error correction information are interleaved and spread out over the spiral, so that a scratch in one place won't ruin all chances of recovering the data via ECC. The point is, a CD-ROM is a bunch of blocks, just as a hard drive is.) At write-time, all CD-writing software that I know of does things in terms of 2048-byte sectors. Even the CD-writing software that runs under VMS (for example, "cdwrite" and "cdrecord".) If you're really bored you can learn how to do mode page editing on SCSI drives yourself. I learned it a couple of years back when I got a boatload of Micropolis 1.6Gig drives that had been set for 520-byte sectors and wanted to use them in a more "normal" 512-byte mode. Since then the skill has come in handy to connect modern, fast, and "large" (i.e. 9 Gbytes or larger) SCSI drives onto systems that don't deal with drives that large. Just go in, edit the disk capacity mode page, and you've got a smaller than 1 Gig drive that never has to seek very far :-). -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927