CONTROL UNIT TEAM 1: Miguel Harmant Rodney Rodriguez Elias Crespo Javier Parra Alfredo Alonso Marc-Wayne Anglin
Dec 28, 2015
CONTROL UNITTEAM 1:
Miguel Harmant
Rodney Rodriguez
Elias Crespo
Javier Parra
Alfredo Alonso
Marc-Wayne Anglin
WHAT IS A MICRO-INSTRUCTION?
WHAT ARE MICRO-OPERATIONS?
BASIC CONCEPTS
• Single instruction in a micro-program.
• 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.
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.
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.
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.
EXAMPLE OF THE CU OPERATIONS
FETCH-CYCLE Control signal Sequence
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
TYPES OF CONTROL UNIT
RISC architecture CISC architecture
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.
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.
Control matrix
It receives input from the ring counter and the instruction decoder and provides the proper sequence of control signals.
REVIEW QUESTIONS?1. What are the basic micro-operations?2. What are the three main components of
the CPU?3. What is the Control Unit?4. What are the two basic functions of the
Control Unit?5. What are the two types of Control Unit?6. How are they constructed?7. What is RISC and CISC?8. Which are the differences between the two
types of Control Unit?9. What are the advantages of each?10. What are the disadvantages of each?