Grrr - !%#*^@# Kaypro!

Fred Cisin cisin at xenosoft.com
Wed Aug 3 18:08:22 CDT 2005


On Wed, 3 Aug 2005, Allison wrote:
> 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.

--
Grumpy Ol' Fred     		cisin at xenosoft.com



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