23 Nov
2014
23 Nov
'14
8 p.m.
On 11/23/2014 06:53 PM, Fred Cisin wrote:
On Sun, 23 Nov 2014, Jules Richardson wrote:
It's 128-byte MFM (not FM) that's the problem with a huge swath of PC
controllers. And, wouldn't you know it, there were a few systems using
just that.
The National Semi DP8473 is one of the controllers that can pull that
one off. Apparently they reverse-engineered the NEC 765 and didn't
reproduce the bug. Shame on them! Didn't they understand
"compatibility"? And yes, the same NS controller handles FM flawlessly.
--Chuck
Some PCs will write SD, of course, although I
think far fewer will write SD
and 128 byte sectors.
The good news is that the Osborne single density was 256 bytes per sector.
10 sectors per track, single sided, 40 tracks