Registers

• Performs arithmetic and logical operations, such as fixed point and floating point arithmetic, logical operations (AND, OR, XOR) and shift operations. • Inputs are from the internal bus and the accumulator, with outputs routed to one of the registers.

Main function is to fetch program instructions from memory, to decode them and to execute them serially.

System clock sends a signal to each of the computer components on a regular basis to synchronise all of the computer operations

A fast memory location that exists in the processor or the I/O controller. The computer consists of general purpose and dedicated registers

normally named R0, R1, R2, etc.) can be used to hold instructions and data temporarily

are used by the processor to carry out a specific role

• Special register used as fast temporary storage by the ALU • stores the results of any calculations processed by the ALU.

Used to hold the status of various flags indicating e.g. positive result, negative result, carry bit used, overflow error, and interrupt status. The details of the SR storage are dependent upon the processor involved.

Register that holds the address of the next instruction to be fetched

Holds the address of the current instruction being executed

Holds the instruction from the (MAR) and the associated data

Used to store the instruction that is to be decoded and executed.