- Computer is a system
- It receives inputs, processes it, and produces outputs
- Without losing generality, we can restrict input as string of 0 and 1
- Any object can be represented as string of 0 and 1
- Output of the system also string of 0 and 1
- In general, there’s no restriction on how the system mapping input to output
- Because of physical limitation, system can only receive input and produce output string in limited size at a time
- It is desirable for the system to be able to store the current output and feed it as an input for later processing
- There’s feedback line from output to input.
- Capability of storing outputs is done using memory of the system
- Because there are many strings stored in memory, the system should be able to distinguish one from the other
- There’s an address for every place to put string in memory