Re: AEHD drive

[david@uow.edu.au (David Wilson)]

shack@southwind.net (Randy Shackelford) writes:
>Yeah, that must be why they went to MFM on floppies when GCR can handle 1.6
>mb, as AE supported. As everyone knows, MFM can only do 720K and 1.4 mb on 
>DD and HD disks respectively while GCR does 800K and 1.6 mb.

Is it really GCR that gives the extra storage or is it the variable speed
recording that does it? MFM disks do not get extra sectors on the outer tracks
like Apple disks do.

Apple 800KB 3.5:
Tracks	0..15	12 sectors/track
	16..31	11
	32..47	10
	48..63	9
	64..79	8
		--
		10 average

MFM 720KB 3.5:
Tracks	0..79	9 sectors/track

Thus if an MFM disk could use more sectors on the outer tracks it would
hold more data than an Apple GCR disk. If it used the same 5 bands and could
fit one extra sector then it would be 880KB (strange - that number rings a
bell - do Amigas get that much on a disk?)
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia