Xref: utzoo comp.sys.amiga.hardware:3201 comp.periphs.scsi:978 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!ncrlnk!ncr-mpd!Chuck.Phillips From: Chuck.Phillips@FtCollins.NCR.COM (Chuck.Phillips) Newsgroups: comp.sys.amiga.hardware,comp.periphs.scsi Subject: Re: Can CD ROMs be read by an eraseable optical disc drive? Message-ID: Date: 27 Aug 90 06:32:00 GMT References: <6170@hub.ucsb.edu> Sender: uucp@ncr-mpd.FtCollins Distribution: comp Organization: NCR Microelectronics, Ft. Collins, CO Lines: 67 In-reply-to: 6600dan@ucsbuxa.ucsb.edu's message of 25 Aug 90 23:44:27 GMT First, I'd like to thank Dan Zerkle for his detailed response to my query about using the same drive for both CD ROMs and read/write optical disks. >>>>> On 25 Aug 90 23:44:27 GMT, 6600dan@ucsbuxa.ucsb.edu (Dan Zerkle) said: Dan> Sorry, not possible. The media, although similar, are different. ... Dan> Read/write optical disks (I'll say "floptical," though that is very Dan> inaccurate) are the same size and shape, but they come in plastic Dan> cartridges. Take a look at one of your 3 1/2 inch floppies and Dan> imagine it in a 5 1/4 inch size with an optical disk inside, and Dan> you'll start to get the idea. How about a plastic case for CD ROMs to achieve physical compatibilty? This approach has been used to allow mini VHS tapes to be played by standard sized VHS machines (and cassettes to be played by, ugh, 8-track machines:). Dan> The disks themselves actually look different. You can actually see Dan> the sectors laid out on a floptical, 11 per track. Then, using my near negligible knowlege of SCSI, I suppose the software to retrieve data is buried in the drive somewhere and not possible to override on _existing_ read/write drives. (Please, someone tell me I'm wrong!) Dan> The recording method is entirely different. ... Attempted writes to a CD ROM should be a big no-no anyway. Dan> The reading method actually somewhat similar. You see how your laser Dan> reflects off the surface of the disk. This will be different, Dan> depending on whether your crystals are aligned (new age data storage) Dan> or whether a pit has been burnt. Questions: Would it be possible for the same optical device to read both types of disks? Alternately, would it be possible to physically fit the required optics for both formats into a single box? Would it be physically possible to design a drive fit for both formats? (After a failed read of one format, the drive could switch to the other automatically unpon disc insertion or simply use the disc's form factor for deciding.) I realize now it's improbable an existing drive could work, but I'm wondering if some enterprising hardware company out there is looking into this. How about using a plastic adaptor and a raw Sony mechanism (i.e. sans SCSI) with special firmware wrapped around it? Dan> I just want to know how the pricing is set. You can get a new NeXT Dan> for $6.5K, which includes a read-write optical drive, along with lots Dan> of ram, processors, monitors, interfaces, and whatnot. On the other Dan> hand, a Sony mechanism erasable optical drive in a SCSI box costs $4k. Dan> Why so much? At a NeXt demo, I was told Mr. Jobs got special pricing because he committed to the technology (provided a beta site, etc.) long before it was a viable product. However, I find it difficult to believe that either Sony or NeXt is selling at a net loss. Hmm...so the effective price of a NeXt _computer_ is only $2.5K, eh? Alternately, you could look at the NeXt as an read/write optical drive with a _very_ large cache. :-) Dan> Dan Zerkle 6600dan@ucsbuxa.ucsb.edu 6600dan@ucsbuxa.bitnet (805) 968-4683 Dan> Amiga.... Because life is too short for boring computers. #include -- Chuck Phillips MS440 NCR Microelectronics Chuck.Phillips%FtCollins.NCR.com 2001 Danfield Ct. Ft. Collins, CO. 80525 uunet!ncrlnk!ncr-mpd!bach!chuckp