> At 17:15 6/01/98 -0500, PG Manney wrote:
>
> >> > MFM (early 80's?)
> >>
> >> Very early 80's, I think, for the ST-506.
> >>
> >> > RLL (late 80's?)
> >>
> >> I tend to think of this as a minor variation of MFM, myself :-)
> >
> >Not quite. The interface is the same (ST-506/412), but the encoding is
> >different.
> >
> >RLL-encoded ST-506/412 drives were finicky, especially as regards
> >temperature -- you shouldn't LLF them cold, for example.
>
> The problem, however, as I understand it, wasn't the ST-506/412 interface
> itself, it was the fact that most of the drives that used this interface
> used stepper motors to move the R/W heads. The high-end voice-coil drives
> that used the
> ST-506/412 interface were *far* more reliable, and usually didn't have any
> problems using RLL encoding.
Based on my experience...
95% true, but using RLL on stepper is fine but the main problem was
when the maker produced drives to work with RLL used faster stepper
design (makers tends to pack with lastest on next generation and
leave the older alone instead of improving it more to pack more info
instead of increassing performance which is perferable.) and that
also include fast stepper type seeking on MFM drives as well. That's
where you see the trouble. Noisy stepper ones tends to wear out
than those ones that does quietly and slowly.
That is why the slow quiet stepping drives like ST225's lasted so
long that platter wore more smoother and got stuck or lasted longer
anyway! :)
Voice coil is best way to up the performance and pack more info.
I can't attach "reliablity" to anything, only maker can do to assure
this requires careful design and choosing right ideas and
applications, making sure it's not cut on the corners and careful QC
in production yields reliablity. Does not need cost like that just
careful job and do the job right once.
Jason D.
>
> Regards,
>
> | Scott McLauchlan |"Sometimes the need to mess with their heads|
> |Information Services Division| outweighs the millstone of humiliation." |
> | University of Canberra |__________Fox_Mulder_"The_X-Files:_Squeeze"_|
> | scott_at_isd.canberra.edu.au |http://www.canberra.edu.au/~scott/home.html |
>
>
>
Received on Wed Jan 07 1998 - 17:01:43 GMT