2 Main memoryCPUArithmetic/Logic Unit( ALU )Control UnitRegister(s)
3 RegistersThe special storage devices in the CPU that CPU uses over and over again for execution of stored-program instructions.There are two types of registers :General purpose registersSpecial purpose registers
4 Registers Examples of special purpose registers : PC ( Program Counter )IR ( Instruction Register )MAR ( Memory Address Register )MDR or MBR ( Memory Data Register or Memory Buffer Register )PSW ( Program Status Word )etc.
5 CPU Main Memory Control unit Data bus Control bus Address bus R0 R1 MDRIRMARPCALURNControl unitData busControl busAddress busCPUMain Memory
7 Main Memory Operations Memory read operationTransfers the content of a specific main memory location to the CPU.The content of the main memory location remains (unchanged).
8 Main Memory Operations Memory write operationTransfers a word of information from the CPU to a specific main memory location.Destroys the former content of the main memory location.Memory access timeThe time it takes to perform a memory read or a memory write operation.