Hola Blacky,
I am pleased you are making progress with your study project – there is indeed much to learn and understand.
You should be able to observe the step and direction signals from the parallel port with an oscilloscope irrespective of Mach3 being the demo version or not. Just remember that the step pulses are of short duration and there may be many of them in quick succession so you need a reasonable quality scope.
I love that video, especially where it says "wire everything up, plug it into the computer and you’re done”.
Unfortunately, it’s not really that simple, Mach3 is basically an open loop control system which sends out step and direction signals – It is then up to the machine controller to interpret those signals into an exact positional movement. To do this the machine controller could use propriety IC’s to control stepper motors or servo motors with encoder positional feed-back, in any event the electronic technology behind this is quite complex.
When Mach3 issues the instruction for a machine axis to move (the direction signal followed by the required number of step signals) it really has no idea if the instruction has been completed, it just assumes that it has, so it up to us (the operator) to create suitable GCode that is within the realms of our machines capability.
I could ramble on but this is perhaps enough for now.
Please, don’t even consider attempting to build a CNC controlled machine out of old CD drives. In my opinion, it would be just about as successful as building a perpetual motion machine.
Tweakie.
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