Inside the CPU keyterms:

Registers

• PC - program counter - Increments on each clock cycle.
• MAR - Hold the address of the next instruction to be dealt with and normally takes its value from the Program Counter (unless CPU running interupt or jump inscrutctions).
• (c)IR -This holds the current instruction, whilst it is being handled.
• Memory Data Register - This holds an item of data as it is copied between memory and the CPU.
• ARITHMETIC LOGIC UNIT - Register in which values are stored to have calculations applied to it.
• ACCUMULATOR - Register on which values are stored to have calculations applied to them.
• CONTROL UNIT - Unit which manages dataflow through the CPU.
• FETCH-DECODE-EXECUTE (cycle) -
• CPU - Processing Unit - comprised of ALU and registers.
• I/O - Input and output devices

Buses - Wires that allows the flow of data through the CPU.

• Data bus
• Address bus
• Control bus

https://en.wikibooks.org/wiki/A-level_Computing/AQA/Paper_2/Fundamentals_of_computer_organisation_and_architecture/The_stored_program_concept

http://cse4k12.org/how_computers_work/