PS - those contacts in the throttle switch. The computer doesn't really need to know the actual position of the throttle - it gets all the info it needs to know about the air going into the engine through the air temp sensor and the manifold air pressure sensor. That switch does two functions.

1) Idle circuit: To squeek by early emissions laws the computers had a special idle circuit which was individually tuned on the line with an adjuster on the box. This fine tune adjustment is ignored when the throttle is anywhere but closed. So there are a couple of contacts in the switch to indicate this.

2) 'Accelerator pump': When you suddenly open the throttle on any car the engine needs just a bit of extra gas or it will stumble slightly. To do this they have the throttle switch send some pulses to the computer - which just adds an extra injector firings for each pulse (typically injectors are fired only when the trigger contacts in the base of the distributor pulse). There are two independent injector circuits (they fire in pairs) and if you look in the switch a single contact slides up between a sort of interlocking zipper sort pattern of contacts, so as the contact slides up it first hits one side, then the other. Of course you only want this to happen when the throttle is opening, so that portion of the switch is sort of friction loaded, and when the throttle opens it rotates slightly on the shaft and closes a couple of contacts to complete the circuit, when closing those contacts are pulled open so you don't get the extra injector fires as the throttle closes. This 'electronic accelerator pump' action works even if the engine isn't running, turn the key on and if you listen very carefully you should hear the injectors clickng as you open the throttle, not when you close it. If it isn't working the engine will run just about as well as with it working, in fact you can totally unplug the throttle switch plug and barely tell the difference. I think the engine is a little slower to respond to quick throttle openings, but it's not something you'd particularly notice unless you were looking for it.