IDE <-> MFM
ard at p850ug1.demon.co.uk
Wed Dec 3 14:08:55 CST 2008
> what I had been thinking was shouldn't it be somewhat *easy* to make
> an IDE drive into an MFM. Just strip off what you don't need! How do you
> make an elephant...take a piece of stone and remove everything that
> don't look like an elephant! And it's done!
Well, it would be _if_ a modern IDE drive still consisted of a WD1003 +
a simple nead drive. The problem is that it doesn't. All the drive has to
do is look to saftware as if it was a WD1003 + a simple hard drive. The
software interface assumes things like the same number of sectors/track,
But the hardware might well not do that at all. Provided the drive can
accept a cylinder/head/sector number and return a buffer full of bytes,
the software will be happy. The fact that sectors that (to softwre)
appear to be on th same culinder in reality aren't doesn't matter. But it
sure does matter if you want to bypass the built-in controller.
There is then the issue that the signals you want to access may only
exist inside (cusatom) ICs. Not the easist thing to connect to.
And the fact that you won't get real technical information on an iDE
drive. That's the only part of my PC that I don't have scheamtics for. I
tried just aout every manufacturer about 10 years ago, none would supply
them, I douvt that's changed. And the ICs on the sort of drive I was
looking at seemd to consist of a (mask-programmed) microcontroller, an
SRAM (presumably a data buffer at least in part), a little glue, some
recognisable analogue bits, at least one large digital ASIC and at least
one analogue ASIC. Not conducive to being modified.
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