Chuck.Phillips@FtCollins.NCR.COM (Chuck.Phillips) (08/23/90)
I just saw an ad for an erasable optical drive for the Amiga. Question: Would it be possible for the same drive to provide CD ROM functionality (compatible with the CDTV)? Is this only a matter of providing compatible functions in the whatever.device, or is there some physical incompatiblity? Thanks in advance, -- Chuck Phillips MS440 NCR Microelectronics Chuck.Phillips%FtCollins.NCR.com 2001 Danfield Ct. Ft. Collins, CO. 80525 uunet!ncrlnk!ncr-mpd!bach!chuckp
6600dan@ucsbuxa.ucsb.edu (Dan Zerkle) (08/26/90)
In article <CHUCK.PHILLIPS.90Aug23091414@halley.FtCollins.NCR.COM> Chuck.Phillips@FtCollins.NCR.COM (Chuck.Phillips) writes:
I just saw an ad for an erasable optical drive for the Amiga. Question:
Would it be possible for the same drive to provide CD ROM functionality
(compatible with the CDTV)? Is this only a matter of providing compatible
functions in the whatever.device, or is there some physical incompatiblity?
Sorry, not possible. The media, although similar, are different. To
wit:
CD-ROM's look just like the musical CD's. This is why the upcoming
CDTV can also function as a standard stereo component for playing
musical CD's.
Read/write optical disks (I'll say "floptical," though that is very
inaccurate) are the same size and shape, but they come in plastic
cartridges. Take a look at one of your 3 1/2 inch floppies and
imagine it in a 5 1/4 inch size with an optical disk inside, and
you'll start to get the idea. The disks themselves actually look
different. You can actually see the sectors laid out on a floptical,
11 per track.
The recording method is entirely different. CD-ROM's are recorded by
burning jillions of little pits in the plastic (I think). Flopticals
are written by using a very focussed laser to heat a track to its
curie point then using an ambient magnetic field to align the crystals
in the substrate to the direction of the field (I think).
The reading method actually somewhat similar. You see how your laser
reflects off the surface of the disk. This will be different,
depending on whether your crystals are aligned (new age data storage)
or whether a pit has been burnt.
I just want to know how the pricing is set. You can get a new NeXT
for $6.5K, which includes a read-write optical drive, along with lots
of ram, processors, monitors, interfaces, and whatnot. On the other
hand, a Sony mechanism erasable optical drive in a SCSI box costs $4k.
Why so much?
--
Dan Zerkle 6600dan@ucsbuxa.ucsb.edu 6600dan@ucsbuxa.bitnet (805) 968-4683
Amiga.... Because life is too short for boring computers.Chuck.Phillips@FtCollins.NCR.COM (Chuck.Phillips) (08/27/90)
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 <usual/disclaimer.h>
--
Chuck Phillips MS440
NCR Microelectronics Chuck.Phillips%FtCollins.NCR.com
2001 Danfield Ct.
Ft. Collins, CO. 80525 uunet!ncrlnk!ncr-mpd!bach!chuckpmk59200@metso.tut.fi (Kolkka Markku Olavi) (08/27/90)
In article <CHUCK.PHILLIPS.90Aug27073200@halley.FtCollins.NCR.COM>, Chuck.Phillips@FtCollins.NCR.COM (Chuck.Phillips) writes: |> Dan> Read/write optical disks (I'll say "floptical," though that is very |> Dan> inaccurate) What an understatement! Floptical disks are MAGNETIC disks with optical tracking, they have NOTHING AT ALL in common with CD-ROMs, WORMS or rewritable optical disks. Better use the real names of things. |> 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? This would mean fitting two separate head assemblies in the system and duplicating a lot of electronics. It wouldn't be much cheaper than using two separate drives. |> Would it be physically possible to design a drive fit for both formats? Of course it's _possible_, but if it is sensible is another question. What's wrong with using separate drives for CD-ROMs and R/W disks? -- Markku Kolkka mk59200@tut.fi