Hardware components

Von Neumann Architecture

Organisation of the Central Processing Unit (CPU)

Register file

small and fast memory block, array of storage elements

circuitry that enables data to be read from or written to any register

access circuitry:

• read
  • enables two registers to be read at the same time
  • has two address inputs to select registers to be read
  • dual-ported: contents of two registers is available via two separate outputs A and B (ports)
• write
  • data input C and corresponding address input for read

how to realise dual-ported memory units:

Single memory block	Two memory blocks

ALU

used to manipulate data, performs add/subtract and logic (AND, OR, XOR)

two inputs — one from register out A, one from multiplexer

multiplexer either selects register out B, or immediate value in IR

output is connected to data input of registers