On Wed, 10 Dec 2003, Patrick Finnegan wrote:
> On Wednesday 10 December 2003 10:47, Peter C. Wallace wrote:
> > Usually you know the encoding scheme, and I dont see anything wrong
> > with using whatever knowledge you have of the interface to optimize
> > it. If a different encoding scheme is used, an FPGA based design
> > could easily adapt.
>
> "Knowing the encoding scheme" prevents this from being a "universal"
> interface. You'd need to make different version for, say, your PC/XT,
> your PDP-11 with an RQDXn, and TeleVideo TS816. (Or shouse I say "my"
> as those are all system I have that'd benefit from this). At most, (I
> think) you'd need a different cable set for all three of these if you
> didn't claim to "know" the encoding.
No, thats not true, all you need to know is the encoding scheme... The cabling
is interface type specific.
>
> Also, with at least two of these examples, you probably *don't* know the
> encoding method... as mentioned earlier, the RQDX(1) isn't based on any
> 'standard' controller IC. Also, the TeleVideo's controller is based
> upon an 8X300 microprocessor, and may not be RLL/MFM/FM.
The controller implementation doesnt actually matter much. The encoding scheme
is very likely MFM on all the mentioned systems.
>
> > But you're right, its probably possible to undo write-precomp by
> > simulating the drives tendency to push close transitions apart. I do
> > think some adjustments are needed per drive type... The write Precomp
> > value is pretty small - in the order of 5-10 % of the data period.
> >
> >
> > Peter Wallace
>
> Pat
> --
> Purdue University ITAP/RCS
> Information Technology at Purdue
> Research Computing and Storage
> http://www.itap.purdue.edu/rcs/
>
Peter Wallace
Received on Wed Dec 10 2003 - 10:27:50 GMT