The DB25 LPT port on your PC can only supply 12 output pins. Which means a maximum of 6 motors (axis). Each motor requires two pins for control. One for step and one for direction.

If however, you require the use of an onboard relay, you'll have to use one of the output pins to control that relay. Which means you'll lose one of your axis.

If you use two relays, you'll still only lose one axis because each axis uses two output pins. If however, you use a third relay, you'll then lose another axis.

If you require more outputs then 12 you can install a DB25 LPT PCI card into your PC. Then you can add a second break-out board to your system, doubling your computers outputs and inputs.

The break-out boards listed on have all been tested thoroughly and they work quite well.

It is very important to remember to keep a clean running PC. Much of the performance of a good break-out board depends on a very fast and smooth running computer. Back ground programs and app's can mess with the timing and speed of the internal processor. The break-out board depends on a well timed signal. It will only perform as good as the signal it receives from the computer. The better the signal the better the performance.

If you're motors are running rough, missing steps, low speeds etc., it is strongly recommended you look at your PC and check it's performance.

A note about breakout boards.