13 Oct
2008
13 Oct
'08
1:41 p.m.
On 13 Oct 2008 at 18:01, g-wright at att.net wrote:
When I image disked my set, it found both 8 and 10
sector disks. The 3B1 can
format in either 8 or 10 sectors. It looks like the main software is all in 10 sector
disks and the other add on software is in 8 sectors. The 2 disks that failed to image
where from the same add on package, don't remember which and they showed
up as 9 sectors ??? Anadisk finds the same and can read the first 8 sectors and
errors on the 9th.
Depends on what the 9th sector display as. There's a Windoze-related
glitch in the Anadisk sector map code to detect "orphan" sectors;
i.e., those without an address header. If the sector shows up in the
map as "109" or some such, you're seeing the artifact. Try it again
with honest-to-gosh real-mode MS-DOS.
Believe it or not, the "orphan" sector was someone's idea of copy
protection back in the day. Shows up on a "Read Track" operation,
but is otherwise inaccessible. Similarly, some vendors used to put
about 50 orphan IDAMs on a floppy with no data sectors. Or put 2
sectors with identical IDAMs on a track--read one and then read the
other immediately and compare the results. As well as sticking stuff
in the inter-sector gap to identify the disk (I think Harvard
Graphics did that one).
Ah, the good old days.... :(
Cheers,
Chuck