Chapter 10 Instruction Set: Charateristics and Functions

1. Instruction Set:
   • The collection of instructions that a CPU can execute:
   • • The instruction set determines the function of CPU
2. Element of an instrction
   • Operation code(Op code)
   • Source operand reference
   • Result operand reference
   • Next instruction reference
   • 
   • Operands are stored in cache or main memeory or virtual memory, CPU registers, I/O devices.
3. Instruction types:
   • Data processing 
   • Data storage(main memory)
   • Data movement(I/O)
   • Program flow control: test and branch
4. Number of addresses
   • 4 addresses
   • • 
     • A4 is next instruction address
   • 3 addresses
   • • 
     • Next instruction address is usually implicit
   • 2 addresses
   • • 
   • 1 address
   • • 
     • Implicit second address: usually a register(accumulator, AC)
   • 0 address: Op code
   • • All addresses are implicit or no address
     • Uses a stack
5. Types of operands
   • Address
   • Numbers
   • Characters
   • Logical data
6. Types of operations
   • Data transfer: the most fundamental
   • • Specify
     • • Source
       • Destination: registers, memory, top of stack
       • Amount of data
       • Mode of addressing
   • Arithmetic
   • Logical
   • Conversion
   • • Translate: some values in memory are converted by table query
     • Convert: base conversion
   • I/O
   • System control
   • Transfer of control
7. MMX: A set of highly optimized instructions for multimedia applications
   • SIMD execution model
   • • SIMD allows the same operation to be carried out on multiple data elements in parallel. The MMX technology supports parallel opertions on byte, word, and doubleword data elements which contained in MMX registers.
     • 
   • Wraparound & Saturation arithmetic
   • • Wraparound arithmetic: the extra bit is truncated when overflow occurs.
     • Saturation arithmetic: When overflow or underflow happens, the result is set to the largest or smallest value representable
   •