Could someone give me a little insight as to how the ECM can control the advance on a late model (90-92) remote coil HEI.

I have a problem understanding how the advance can be controlled if the mechanicals inside the distributor are not moving (IE wieghts and vacuum)
I'm having current troubles getting my motor to run and need a little info to get a better grasp of what is happening there.
Thanks in Advance (I won't say retard!)
JP

 

The ECM receives a reference pulse from the distributor, which tells it the position of the crankshaft. The ECM then tells the ignition module when to fire the coil.

 

That's what I figured, but I was trying to understand how you could fire the coil in advance of the reference pulse happening?
The other issue that I came up with is that if I set 6 BTDC mechanical baseline timing and my ECM can add a total of 41 degrees of advance (found in my bin file) this is a total of 47 degrees. (may or may not include the base timing figure)
There is only 45 degrees max between positions on the distributor (not including the overlap of the width of the rotor terminal which will actually increase the "usable" degree of rotation for firing each position).
Is the ECM using the previous pulse as the reference for the upcoming firing of the coil?
I'm really overthinking this but it has me asking the question.
JP

 

Probably