Shared Interrupt - when an interrupt can be asserted by multiple devices, it is shared and requires the interrupt handler to poll status - I.e. the handler must read the status of every device that may have asserted the interrupt to figure out which device in fact did.
Shared Memory - when more than one thread on a single CPU or on multiple CPUs can access the same memory locations, this memory is shared, and shared memory must be protected by a synchronization mechanism if reads and writes are allowed.
Signal (Software) -a software signal is often also called a software interrupt and in fact functions much like a hardware interrupt does but at the scheduler/thread level - when a signal is thrown by one thread to another, the throw call causes the RTOS to potentially dispatch the catching threadís handler instead of the code it is currently executing after the catch kernel code is executed - so, a signal can be used to asynchronously interrupt a running thread.
Signal Block Diagram - a systems design method used in SDL (Specification and Description Language) where hardware and software elements can be modeled as blocks with signal list inputs and outputs - inside the blocks at a lower level, all signals are ultimately consumed or generated by EFSMs.