I think the difference between the claim and prior arts are the following:
I) an on-chip event detector which is configured to detect an asynchronous on-chip event specified in the target program during execution of the target program; and
II) trampoline code which is configured to invoke, in response to the event detected by the on-chip event detector, an application-level interrupt handler which handles an interrupt specified for the event by executing a specific portion of the target program;
F) ... at least one pin variable... bound to one of the I/O pins... wherein ... manipulation of each pin variable... configured as an output pin ... will cause a state of the output pin to change correspondingly, and examination of each pin variable ... configured as an input ... will cause a state of the input pin to be detected.
So... the user application can specify some interrupt handler, and an on-chip event detector can detect pin change and automatically execute the interrupt handler.
(II) trampoline code is well known. (F) pin interrupt service is well known. I don't know what event detector is or if it's well known.
A problem I see is that the claim describes a "concept" of a event detector having the ability to execute a particular statement in a user application, but doesn't really teach how it can be implemented.