Allison wrote:
Or does the
index pulse function more like that of a hard-sectored floppy -
i.e. the number of sectors per track is fixed in hardware, and there's an
index pulse at the start of each sector?
Index is once per revolution. Number of sectors is NOT fixed.
Well, that makes life a little easier :)
One problem is that many of the MFM controllers were
into interchangeable.
Oh, sure. But the OP was just asking about emulating a drive - so the for
purposes of that, it doesn't matter: moving controllers might be an issue of
reformatting (LLF + HLF) the emulator, just as it is with a real drive.
Separately, there is a need I think for a modern device that can look like a
*controller* and suck data from old drives, allow it to be interpreted in
software on a modern machine, possibly write it back to a drive etc.
Now that's a more complex project - but I think the problems in emulating a
drive just boil down to making the hardware run fast enough, rather than there
being big logic-type challenges. As people (and yourself) have said,
modern-ish IDE drives of sufficient capacity and memory to use as buffers is
cheap these days.
cheers
Jules