On Wed, 27 Dec 2006 09:26:54 -0800, "Joel Kolstad" Gave us:
It is more than a mere firmware change, and no, none of the single layer burners could do the task. The read head, in particular is different as is the commands that address it's motion, it's range of motion, as well as the software that goes behind setting focus points for the layers, etc.
PERHAPS a FEW drives made as the dual layer technology was being brought online incorporated read/write heads that could do the job, but if so, it was by choice, and those burners WOULD in fact be updatable in firmware, or a mere software flag at runtime.
My first laser disc player was a complete zinc cast optical bench in miniature, complete with a 6 inch HeNe gas tube laser. There were two aim-able mirrors as well as a HUGE main focus lens assembly. This is due to the fact that a 12" platter can have a huge amount of wobble in it. I have seen read head lens move up and down 3/8 of an inch while tracking on the outer areas of a warped-more-than-normal disc. The read head optics were in an assembly that looked exactly like a speaker magnet and voice coil assembly (I still have it).
This is one reason why the 12" form factor went away. the bigger it is, the more it costs to produce, not to mention warehouse, and ship.
Today's integrated laser diode/read sensor/ main lens assembly "heads" could in no way read twelve inch platters. Smaller is better anyway. I'm sure that when holo-disc gets out it will be 3.25" form factor... at like a half a TByte each. It's a brave new world. :-]
I can still remember getting my first full ht 1Gb SCSI drive. I was thrilled. I called it my "black hole". I laugh now thinking back on the hundreds of dollars I sunk into that. I can get a 300GB SATA 2 screamer now for less than a hundred bucks!