Computer Organisation

Document Sample
Computer Organisation Powered By Docstoc
					Computer Structure
What does a processor look
          like?




         Intel Pentium 4
This shows the size of a Pentium 3 processor
• The heart of a computer
  is the central processing
  unit or CPU. This device
  contains all the circuitry
  that the computer needs
  to manipulate data and
  execute instructions.
• The CPU is amazingly
  small given the immense
  amount of circuitry it
  contains.
                RAM
RAM (Random access memory consists
 of a series of memory locations, each
 with its own unique address
• The CPU is composed of four basic
  components: registers, buses, the
  ALU, and the Control Unit.
• To better understand the basic
  components of the CPU, we will
  consider each one in detail.
• In order for a CPU to accomplish meaningful
  work, it must have two inputs: instructions
  and data. Instructions tell the CPU what
  actions need to be performed on the data.
  We have already seen how data is
  represented in the computer, but how do we
  represent instructions? The answer is that
  we represent instructions with binary codes
  just like data. In fact, the CPU makes no
  distinction about the whether it is storing
  instructions or data in RAM. This concept is
  called the stored-program concept.
• Registers: these components are
  special memory locations that can be
  accessed very quickly. Three registers
  are shown: the Instruction Register
  (IR), the Program Counter (PC), and the
  Accumulator.
• Buses: these components are the information
  highway for the CPU. Buses are bundles of
  tiny wires that carry data between
  components. The three most important buses
  are the address, the data, and the control
  buses.
• ALU: this component is the number cruncher
  of the CPU. The Arithmetic / Logic Unit
  performs all the mathematical calculations of
  the CPU. The ALU can add, subtract,
  multiply, divide, and perform a host of other
  calculations on binary numbers.
• Control Unit: this component is
  responsible for directing the flow of
  instructions and data within the CPU.
   John Von Neumann
     architecture
          Backing
          Storage


          Memory

 Input                Output
Devices   Processor   Devices
           (CPU)
The Organisation of a Simple Computer
    Memory Read Operation
         Steps                       Effect

Processor sets up           Pinpoints desired memory
address bus with required   location
address
Read line on Control Bus    Tells the memory location
is activated                that it is to be read from
Data bus transfers data Data is transferred
from the memory location (copied) from memory
to the CPU (data         location to CPU
register)
   Memory Write Operation
         Steps                       Effect

Processor sets up           Pinpoints desired memory
address bus with required   location
address
Processor sets up data      Data ready to be sent to
register with value to be   memory
written to memory
Write line on Control Bus   Tells the memory location
is activated                that it is to be written to
Data bus transfers data     Data is transferred to
to required memory          required memory location
location
  Background Reading

John Walsh Higher Book – pages
           24 - 30

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:3
posted:10/1/2012
language:Unknown
pages:16