3 Aug
2005
3 Aug
'05
4:26 p.m.
From: "Fred Cisin" <cisin at
xenosoft.com>
On Wed, 3 Aug 2005, Allison wrote:
Hi
How about the sector number being bit reversed but
the data not ( my Nicolet 1080 ). Actually it is
a record numbers, not sector but used in place of
sector headers. When I was trying to figure out how
to format the disk, this cause me a lot of grief.
The only record I could get to work was 0.
Dwight
Dwight
Dave, your on track. The CHRN vlaues do not have
to corrospond
to actual head or cylinder. They do not even have to be in order
on the media! The only limits on them are R must be 1 or greater
(less than 255).
Which creates some complications with handling 128 byte sectors (R==0).
My favorite format was sectors 1- 9 (512 DD) on
side one and
side two was 10-19 with H always set to 0.
Easily handled by 765, but not by Int13h.
I have to be careful to differentiate which complications are
due to the FDC chip, which to the FDC board/implementation,
and which are BIOS linitations.
Nitpick: don't you mean 0 - 9 on first side? Or did it actually have 9
sectors on one side and 10 sectors on the other?
I've seen disks with 10h and 20h in the H field.
My favorite was 1 in the H field for the first side and 0 in the H
field on the second side.
And, of course, there are some formats, such as Superbrain,
where the data (sector content) is inverted,
but the headers (CHRN) are not.