16 Jun
2014
16 Jun
'14
6:19 p.m.
On 06/16/2014 05:42 PM, Eric Smith wrote:
OK, I'll give it a go. Are there recommended gap
lengths for that format
I just calculate the gaps out. It's very straighforward. I could check
some of my samples and see if you're really interested.
I don't mean changing the address mark. If you
want to format a disk with
a 177x/179x with sector numbers in the range of 0xf5 through 0xff, you're
going to have problems. Even the 1781 has that problem. The 765 doesn't.
Oh, I gotcha now. About the closest I've seen are some Molecular
formats using 242 (F2) as a head number. Still, the WD does have a
neat feature that if the track data doesn't contain any of the
"reserved" values, you can format and write in the same rev. That
didn't come about in the 765 family until very late in the family.
I know where I can get some. I've always wanted
to try to use that to read
DEC and Intel M2FM formats.
It might be nice to have a couple of spares.
Was there any published app note or the like for the
1781?
As far as I know, just the data sheet (what I worked from back in the
day. The 1771 app notes were helpful to get the general drift of
things). I don't think the chip was ever very popular--and it had an
annoying habit of hanging without any reason, so we had to implement a
control register with a "reset" bit.
--Chuck