Zane H. Healy wrote: Does it have a little "PD" logo on the metal shutter? If so, it's probably one of the Panasonic "PD" (phase-change digital) discs. I remember reading about these in the mid-1990s, just before CD-RWs became widespread. They never really caught on (I certainly don't recall anyone selling the drives or the discs) and AIUI died off some time in the early '00s. There's a (small) amount about them on Wikipedia: <http://en.wikipedia.org/wiki/Phase-change_Dual> Basically, they store 650MB of data, and work similarly to a CD-RW (i.e. phase-change recording). You can read, write and erase them a few thousand times, but they're not readable in standard CD drives. Apparently a first-generation Panasonic DVD-RAM drive (that'll be the ones that take the big cartridges) can read them, but I suspect finding one of those in working condition might be difficult. Finding a working PD drive would probably be even more difficult... optical drives don't usually stay working for long IME. -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

2009/5/6 Zane H. Healy <healyzh at aracnet.com>: Just sold 2 of 'em on eBay, plus a dozen media. Still have 1 or 2 disks knocking around somewhere. Dual-purpose drive. Acted as a standard CD-ROM on one LUN, and on the other, was a R/W optical drive with CD-sized disks that came in a permanent cartridge. Had 2 access LEDs on the front, or 1 that changed colour. The drive could detect which type of disk was inserted, so on a Windows box, either (say) D: worked - R/O - if a CD was inserted, or E: worked - R/W - if a PD cart was inserted, but never both at once. This screwed up the boot process on some BIOSes - you needed to insert a CD, any CD, before power-on, so that the drive was active and detected *in CD-mode* by the BIOS (I presume as a drive-ready signal or something like that) so that you could boot off it. I've used 'em with DOS, Windows 9x, NT, Linux and FreeBSD - they were quite handy, before CDR and CDRWs were remotely affordable. I don't remember how much either drives or media cost, but when CD-burners were thousands, these things were hundreds. A PD held 650MB so you could fit the entire contents of the average CD-ROM on one. Before the days of overburning, anyway. I had one internal EIDE and one external SCSI. I planned to use them, for the last time, for server backup & data transfer to a web server in a DMZ, but I never got round to setting it up... So in my last clearout, I flogged 'em off. Anything else I can tell you? I'm afraid my knowledge is usage experience, rather than technical detail. -- Liam Proven ? Profile: http://www.linkedin.com/in/liamproven Email: lproven at cix.co.uk ? GMail/GoogleTalk/Orkut: lproven at gmail.com Tel: +44 20-8685-0498 ? Cell: +44 7939-087884 ? Fax: + 44 870-9151419 AOL/AIM/iChat/Yahoo/Skype: liamproven ? LiveJournal/Twitter: lproven MSN: lproven at hotmail.com ? ICQ: 73187508