Important Concepts  Parts of the CPU  Arithmetic/Logic Unit  Control Unit  Registers  Program Counter  Instruction Register  Fetch/Decode/Execute Cycle  Machine Language  Stored-Program Concept  Bus  Direct Memory Access

Types of Instructions  Transfer Operations  Load  Store  Arithmetic/Logic Operations  Addition, Subtraction, Multiplication,...  AND, OR, NOT, XOR  Shift, Rotate  Control Operations  Unconditional Jump  Conditional Jump (Jump if Register > 0)  Halt

Additional Types of Instructions  Input/Output Instructions  Direct Memory Access Instructions  Graphics Operations

Reduced Instruction Set Computer  Minimal set of instructions  Complex operations are divided into simple steps  Simple steps are encoded as the instructions  Macro-instructions are small programs, called microcode  Instructions execute very quickly  Faster cycle, but requires more operations  Chips require less power consumption

Complex Instruction Set Computer  Complex instructions  Require more time to execute, but do more  More, specialized, operations  Can include memory, graphic operations  Instructions slower to execute, but do more

Stored Program Concept  Program can be treated as data  Program can be changed in memory, read/written to storage  Allows computer to be flexible  Different kinds of programs:  Machine code  Assembly Language  High-level Language  Logic Programming  Programs can be translated from one from to another

Machine Instructions  Instructions are encoded as binary strings, e.g.,  Instructions have op-codes and operands  Operands are the data (or where to find the data)  Op-code specifies the operation that is done to the data  Instructions may be fixed or variable length

Fetch/Decode/Execute Cycle  The program counter keeps track of the next instruction to be executed  The next instruction is fetched and place into the instruction register  The control unit decodes the instructions – interprets the op-code, finds the operands  The instruction is executed – the control unit causes the ALU to do the proper operation based on the op-code  A Jump instruction may change the program counter