Physical Realization of State Variable
Software: as program variable in memory
hardware: wire (connecting sub-circuits)
? wires contain current value of state variable, provision of refresh to remain current
A state variable x is interpreted as a function from Time to its range of values, e.g., x is boolean, we have Mb x: Time ? B
Example: Analog signal coming from microphone of a telephone. Signal can be represented by state variable (interface) Mv voice:Time ? Freq.
The interface of an AD converter transforming analog input to discret 8-bit sample can be described as follows:
COMPONENT adconvert(in: analog_frequency; out: [0…255])