Electronic ignitions do have dwell. [img]http://ourworld.compuserve.com/homepages/JET_AV8R/Vision/Ignition/hei.gif[/img]
The NPN transistor shown, does the same thing points do. When the the transistor is turned on, current flows through it and the coil just like when points are closed. The difference is that you don't adjust the dwell.
This page will tell you all about the different ignition systems commonly used. A good refresher read for all of us.

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'67 GMC 3/4 292 4spd