At the heart of the PCM is the 68332 processor. This processor is geared towards automotive and robotics control. This means that there are some additional commands included such as the boxed table look up commands, and the math co-processor present in other 68XXX MPUs is instead replaced by the TPU, or timing processing unit. This is a somewhat nebuluous piece of internal hardware that you wont have direct access to in the code. Its main purpose is to independantly process timing based events such as the MAF frequency input, crank position reference pulses, etc. with the intent of reducing the load on the main processor. It has its own 'microcode' that it executes to interface with the hardware and read in the various inputs. The places where you will see it is mainly when the PCM handles timer updates and periodic input reads like the crank reference pulses and outputs, such as the injector pulsewidths for each cylinder
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