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Control Unit

Control Unit. TEAM 1: Miguel Harmant Rodney Rodriguez Elias Crespo Javier Parra Alfredo Alonso Marc-Wayne Anglin. Basic concepts. WHAT IS A MICRO-INSTRUCTION?. Single instruction in a micro-program. . WHAT ARE MICRO-OPERATIONS?.

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Control Unit

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  1. Control Unit TEAM 1: Miguel Harmant Rodney Rodriguez Elias Crespo Javier Parra Alfredo Alonso Marc-Wayne Anglin

  2. Basic concepts WHAT IS A MICRO-INSTRUCTION? • Single instruction in a micro-program. WHAT ARE MICRO-OPERATIONS? • Smaller series of steps that compose a micro-instruction. • Atomic operation by the CPU. BASIC MICRO-OPERATIONS • Data transfers between registers. • Data Transfer from registers to memory • Data transfer from memory to registers • Logic and arithmetic operations.

  3. Basic components of the cpu • ALU - does the actual computation or processing of data. • Registers - set of internal memory. • Internal Data paths (Bus) - need to transfer data between the various registers and the ALU. • External Data paths - distribute data to other components. • CONTROL UNIT -controls the movement of data and instruction into and out of the CPU and controls the operation of the ALU.

  4. Cpu structure

  5. What is the control unit ? •  Is the circuitry that controls the flow of information through the CPU. •  It coordinates the micro-operations of other units within it. •  In other words, it is the brain within the brain.

  6. Basic Functions of the cu • Sequencing • Stepping through the micro-instructions. • Maintaining proper sequence. • Execution • Interpreting input signals into output control signals. • Executes Control signals.

  7. Example of the cu operations • MAR <- (PC) • Control unit activates signal to open gates between PC and MAR  • MBR <- (memory) • Open gates between MAR and address bus • Memory read control signal • Open gates between data bus and MBR •  IR <- (MBR) •  Open gates from MBR to Instruction Register FETCH-CYCLE Control signal Sequence

  8. Basic architecture of the Control UNit

  9. TYPES OF control unit • Hard-wired • Designed as a combinatorial and sequential logic circuit. • Input logic signals are transformed into output logic signals, which are the control signals. • Faster. • Micro-programmed • The control signal values for each micro-operation are stored in memory. • Micro-operations that compose control signals are read from memory. • Simpler to modify and construct. RISC architecture CISC architecture

  10. Hard-wired Control unit basic design

  11. Example of a basic computer hard-wired implementation

  12. Components description • Instruction Decoder •  Takes the input from the op-code field of the instruction register and activates one of its 8 output lines. •  Each line corresponds to one of the instructions in the computer's instruction set. • Different Control Signals are produced depending on the op-code.

  13. Components description (continued) • Ring Counter • Continuously cycles from t0 to t5.

  14. Control Matrix

  15. Control matrix • It receives input from the ring counter and the instruction decoder and provides the proper sequence of control signals.

  16. Instruction set for the Basic computer

  17. Instruction set for the Basic computer(continued)

  18. Timing diagram

  19. Review Questions? • What are the basic micro-operations? • What are the three main components of the CPU? • What is the Control Unit? • What are the two basic functions of the Control Unit? • What are the two types of Control Unit? • How are they constructed? • What is RISC and CISC? • Which are the differences between the two types of Control Unit? • What are the advantages of each? • What are the disadvantages of each?

  20. End of presentation

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