hey everyone  i'm getting progress in my study project thanks to Mr Brett and the others ^^
i have some questions if you don't mind :p
1- i want see & study the signal of the mach3 from the parallal port pins  in the oscilloscope is that possible in the demo version ? ... in fact i have tried but i saw an odd signal ! like this .... ! !   !!     !!    !! !   ! !! !  (sorry for the bad Representation with the Exclamation marks hhh )  ... i thought that the signal is a pulses  ... is it cuz of the demo version ? ... is there another way to see the signal in the pc ? wth protus isis or anything like that ?
2- i have watched a video on youtube about making a simple home made cnc machine with 2 old cd drives ... can i contole it wth mach3 ? how if that possible ^^
thx a lot i apreciate your help ^^ ...
ah i almost forgot this is the video link :
http://mods-n-hacks.wonderhowto.com/how-to/build-cnc-machine-using-two-old-cd-drives-222264/
^^

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.

thank you a lot Mr Tweakie your post was sooooo helpful mmmm i am in kind of Miserable sitution because there is no time left for me to the presentation day and i need to show them somthing 
i was thinking to show them that " 2 old cd drives idea " with any controling system the important thing is to show them the basic idea of the cnc machine ^^ ..... they gave the project with this name " controling cnc machine " ... duration " 2 months " ... is that possible ? .... our education system is Corrupt ... and this time i am the victim =) .... thanks again MR tweakie ... i wish life will give me more time to be here in this nice forum with nice people like you not for a graduating project but for the joy of science !