Computer Systems - Architecture

1
Computer System Architecture
Academic PowerPoint
2
Computer System

• A computer system consists of
• HARDWARE (physical machinery)
• SOFTWARE (applications, programs)

3
Computer

• A computer consists of
• Input/Output devices
• CPU (Central Processing Unit)/System Unit
• Memory
• Secondary storage

4
A Computer
System Unit
Memory
Input/Output
Secondary Storage
5
Computer Types

• Computer types range from small personal
  computers to large supercomputers.
• In between are the categories of servers,
  minicomputers and mainframe computers.

6
Personal Computers (PCs)

• Relatively small
• Inexpensive
• Designed for single users
• Desktops, laptops, notebooks, palmtop
• Becoming increasingly powerful
• Very popular

7
Personal Computers (PCs)

• Embedded
• computers or processors that are placed inside
  other objects
• cars
• stereos
• household appliances (video, ovens etc)
• video systems

8
Servers

• Computers that are designed to support a network.
• Powerful CPU
• Capable of using more than one CPU
• Large memory
• Large storage capacity
• High speed communications

9
Minicomputers

• Computer systems that can accommodate several
  users at the same time.
• Large storage capacity.
• Excellent processing capabilities.
• Used in small business

10
Mainframes

• Large, powerful and fast.
• Can accommodate a large number of users at one
  time.
• Requires separate room.
• Used by larger companies and organisations.

11
Supercomputers

• The most powerful and fastest.
• Very expensive.
• Used for complex calculations, military
  applications, simulations and high tech
  businesses.

12
The System Unit

• This is where program instructions are executed
  and data is manipulated
• Components
• motherboard
• memory
• co-processors
• microprocessor and CPU

• buses
• expansion slots
• ports

13
Motherboard

• The main board that contains the electronic
  components of the system unit.

14
Microprocessor CPU

• On a PC the CPU is contained on a single circuit
  called a microprocessor.
• An integrated circuit is also called a chip, that
  is etched on a small slice of silicon.

15
CPU Components

• Control Unit (the brain)
• co-ordinates the control of data and repeats the
  machine cycle

16
CPU Components

• Arithmetic Logic Unit (ALU)
• performs arithmetic logic operations
• Registers
• temporary storage locations for data immediately
  before, during and after execution by the CPU

17
CPU Characteristics

• Speed
• Clock speed (an electronic impulse) affects the
  machine cycle
• Measured in megahertz (MHz)

• Machine Cycle
• The time taken is a fraction of a second
• MIPS (millions of instructions per second) are
  used to measure machine cycle time

18
Memory

• Read Only Memory (ROM)
• Random Access Memory (RAM)
• Located close to the CPU
• Working storage area for system and program
  instructions and data.
• Fast access

19
Co-processors

• A form of multiprocessing
• more than one processing unit
• This speeds processing by executing specific
  types of instructions while the CPU processes
  others.
• Examples of co-processors include maths and
  graphic processors.

20
Buses

• Buses are the physical wiring that connects other
  system components.
• Data is transferred along these buses
• The number of bits a bus line can transfer at any
  one time is called the bus width
• 32 and 64 are common bus widths

21
Expansion Slots

• A socket that is used to connect a circuit board
  to a device
• sound card, network card
• The socket that holds the card is connected to a
  bus that is connected to the CPU.

22
Ports

• A socket that is used to connect a peripheral
  device (printer, scanner etc) to the system unit.

• Parallel Port
• Used when large amounts of data are sent or
  received.
• Printers, disk drives

• Serial Port
• Transmits one bit at a time
• Much slower than parallel
• Mouse, keyboard