Tracing the parallel port is in general much more difficult than tracing
scsi. There are several reasons for this:
- Most access is done direct, so you can not plug in some logging stuff.
- The timing is sometimes cruical. Low level debuggers like softice
change this when logging port i/o.
- You can not use a second parallel port for tracing because you are
to slow to see everything
There are several solutions to solve those problems.
In our case, the low level stuff is done through a vxd. Therefore WINE and
the dll stuff is not working.
- Insert a logging dll between the program and the actual dll
- Use special patched WINE
- use a logic analyzer
- use softice
- buy a scsi scanner
Following commands were used:
macro dumpit ="db C004A000 L6020;ed C004A000 C004A010;f C004A000 L6000 00; x"
bpx vpm2xd+19f8 if *(C004A000)>=C0050000 do "dumpit"
bpx vpm2xd+1837 if *(C004A000)>=C0050000 do "dumpit"