22 Dec
2003
22 Dec
'03
3:27 a.m.
On Sun, 21 Dec 2003, Rich Sias wrote:
I HAVE a Deluxe Option Board. I am trying to get it to
write to a 1.44
floppy. Is there a limit to cable lengths being used before problems
arise? TCM & TE both read 1.44 floppies just fine, but the write
functions do NOT work for me. It has been over 12 years since I have
used this board and I may be missing some steps. I have a printed manual
and I have tried everything I can find in it. Now I am in need of
"experts" suggestions to get it going.
I am trying to copy a plain 1.44 Mb floppy as an exercise. I want to
copy tracks 80-81 to see if that captures some copy protection of a
protected disk. (The company does not replace lost disks, just SELLS you
another registered copy) Running diskcopy gets you an Unregistered copy.
Doing diskcomp shows them to be identical. The difference must be in
tracks 80-81 or other places diskcomp doesn't pay attention to.
This reminds me of an interesting technique I saw implemented on the Apple
][. Apple's low-level disk sector format has a three byte sector header
prolog and epilogue, and a three byte data prolog and epilogue. But the
third byte of the epilogue is basically ignored. So you can format a disk
and use a non-standard byte for the third epilogue byte. When you use a
fast copy program, it will write the new disk out using the standard
epilogue bytes.
So some pirate wrote some code that would check the third epilogue byte to
see if it was modified. If not, it would run a short routine that would
ask you to enter your name, and it would then add it to a list and show
you all the other people your copy had passed through. It would then
write out the modified epilogue byte to a certain sector and you would
never see that routine again (until you copied the disk again and then
it would appear on the new disk).
It was a very clever way to know when a disk was copied. This wouldn't
work if you used a bit copy program because that would copy the disk
verbatim (i.e. including the modified epilogue byte).
--
Sellam Ismail Vintage Computer Festival
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