On 7 Apr 2007 at 3:58, Dave McGuire wrote:
Very dusty neurons are telling me that, generally
speaking, if a
drive has plated media, it'll usually deal with RLL just fine, even
if not designed specifically for RLL use.
I seem to remember someone explaining it as oxide-coated media not
being able to relay the flux reversals sufficiently accurately in
time (they were sort of "blurry"). Plated media does much better in
this respect.
I recall having two ST225s sitting in front of me--one being the
standard version and the other being the "R" version and being unable
to discern any difference at all in the drive electronics. It could
have been that the "R" drives were simply selected from the current
production via testing and otherwise had nothing special to them.
Most of the non-RLL-rated drives that I had worked fine under RLL.
My 5160 box still uses a Quantum 30MB drive with an RLL controller
giving me about 45MB. I've got some big 1224-cylinder drives (Atasi,
Priam) that still work just fine with a supplemental driver (1024
cylinder BIOS limit problems) on a WD 1006SR2. Noisy buggers,
though.
But this is (2,7) RLL encoding. There were others, including one
called something like "ARLL" from Perstor which used a different
encoding (4,7 maybe?) for even more storage gain over standard MFM.
I never had a lot of luck with those and didn't bother to keep any as
far as I can remember.
On the subject of old 3.5" hard disks--many of the early ones had
miserable reliability. In particular, some of the early Conner
drives would simply begin showing rapidly progressing media errors
until they were practically unusable.
Cheers,
Chuck