bet@ecsvax.UUCP (05/23/84)
An additional tidbit -- number of the sector you should read and write
varies with disk format. I use single sided 9 sector disks, and on this
format the correct sector is sector "C" hex. The debug session looks
like this:
A>debug
-l 0 0 c 1 <-- "c" is sector number
-e 77
xxxx:0077 0F.00 <-- you type the 00
-w 0 0 c 1 <-- "c" is sector number
-q
If neither sector "f" nor sector "c" is correct, try loading others
looking for hex "0F" at offset 77 into the sector. For a sure-fire
check that you have the right sector, type:
-u 71
which asks to unassemble starting at offset 71. You should get something
like this:
xxxx:0071 EB05 JMP 0078
xxxx:0073 C6066B060F MOV BYTE PTR [066B],0F
xxxx:0078 9C PUSHF
(and more lines like this)
The line starting at offset 73 is the offending instruction, and the 0F
is the offending immediate data that you are changing to 00.
One more item: I tried benchmarking the speedup and learned some interesting
things. "Diskcopy" is a bad benchmark -- it doesn't speed up. It must not be
using the disk table information. "Copy *.*" from one floppy to another shows
about a 7 to 8 percent speedup, to about the same speed as DOS 2.00.
Bennett Todd
...{decvax,ihnp4,akgua}!mcnc!ecsvax!bet