Hi,
the UC100 is much more than a USB to parallel adapter. There is in fact no such thing that works with Mach. Inside the UC100 is an FPGA
which generates the pulses required for the motor drives which makes it a genuine external motion controller. What it does have in common
with a parallel port is the pin numbering.
The pins capable of output are pins 2-9,1,14,16,17. The pins you mention are input pins, maybe home switches for axes X,Y and Z, but not
output pins.
Each axis requires two output pins, step and direction.
So for instance you may chose:
Xstep=1
Xdir=2
Ystep=3
Ydir=4
Zstep=5
Zdir=6
which leaves outputs 7,8,9,14,16,17 for spindle control, pumps, fans etc.
It maybe that the pinout of your machine restricts your choice, can you post the details of your machine control box?
Craig