Ah yes, the main axe to grind with the printer port.
During bootup, windows (and the PC BIOS) does some crazy things. Outputs are turned on and off.
If you have inputs wired to your printer port, try attaching one to the printer port ground, see if it acts differently.
(NOTE: I said INPUTS which are pins 10,11,12,13, and 15, DO NOT connect any other pins other than these directly to the ground! You can fry your printerport if you connect an output directly to ground or +5vdc)
The way I got around this was to use one output that always stayed on after the bootup, to disable the drive so the motor wouldnt turn.
I found on several PCs that this magic output was pin 4.
MRotate, when it first starts up, sets all outputs low.
So the trick was to make pin 4 "kill" the drive if it was high.
I did this with a pnp transistor.
Does your drive have a enable input? If so you can do this pretty easily.
Here is a rough drawing which might explain how I did it:
In this drawing I used printer port connections that are standard, the outputs you actually used may be different.
Pin 2 and pin 3 go to the drive direction inputs.
Pin 5 goes to drive enable input.
pin 4 turns the transistor on and off.
If pin 4 is high, the pnp transistor is turned off, so the drive is disabled by the drive enable input being tied to ground through R2.
When pin 4 goes low, the transistor turns on, so if pin 5 goes high, the drive enable input is turned on through form pin 5 through Q4. If pin 5 goes low then drive enable is turned off regardless if pin 4 is high or low.
This circuit is basically a cheap inverter, inverting pin 4's output
If you dont have a drive enable, or you dont want to use it, you can double the circuit to kill the cw and ccw drive inputs much the same way.
The rule is to find which PP output stays high from power up till windows boots, and use it as the disable output.
This can be tricky, because the printer port reader does not work until after windows boots.
I would try pin 4, it has always worked for me, if you have a spare led and resistor (350-400 ohms), you can hook it to pin 4 and ground and watch it while the PC boots. I would almost bet that it stays lit until yo turn it off in printer port reader.
edit: If you dont want to hook the led to pin 4, a lot easier way to test this is to unhook one of your drive inputs and hook the other to pin 4. Boot the pc, if the motor stays on throughout the whole boot up process then this is the one you want to use to control the drive enable. I say unhook one drive input because if both drive inputs are high, the drive goes into braking mode and the motor doesnt run. That is why the motor stops when windows does it thing and turns on all the PP outputs. (I notice in the video that all the outputs are on when pport reader starts.)
Nice video, I appreciate you taking the time to do it, it helps a lot, pictures are worth a thousand words, videos are worth a million or more.
Instead of the transistor you can also use an opto isolator. All parts should be available at radio shack, let me know if you need part numbers.