Central Processing Unit

1
Central Processing Unit
2
Computer System

• a computer system is an electronic digital data
  processing machine
• data -- symbolic representation of information
• a computer process is sequence of states during
  which data is modified in specific ways
• a program is a sequence of instructions that
  direct a process
• Normally carried out one at a time, but recently
  computers have had multiple processors.

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Hardware Overview
Processor
Control Unit
ALU
Output Devices
Input Devices
RAM(Memory)
Auxiliary Storage Devices
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Main Components of a Motherboard

• Central Processing Unit (CPU)
• RAM (main memory)
• ROM chips
• Bus(s)
• Expansion slots and cards
• I/O Ports

5
Running a Computer Program

• In order to add two numbers together the program
  must perform some very basic operations
• The following slides show a program adding the
  numbers 2 and 5 together.
• In a high level language this would look like
  x x y

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The System Clock

• This intricately connected system must somehow be
  tied together so everything happens in sync.
• The synchronization is the job of the system
  clock which is like a conductors baton.
• The original PC had a quartz clock that vibrated
  at 4.77 Mhz, the newer ones operate in excess of
  3.0 Ghz

7
Boot Process

• Power up
• Boot program begins execution
• Diagnostic tests performed
• Load the Operating System
• Check configuration and customization
• Display the operating system prompt

8
The Internal Bus

• A bus is basically a collection of wires which is
  responsible for interconnecting the various
  components of a microcomputer together in order
  to allow the exchange of data between these
  components and to provide power to them.
• The internal bus is used to connect internal
  devices such as hard drives, CD Rom drives,
  sound cards, graphics cards, and network cards.
• A minimal bus has to feature three types of
  lines,
• Control lines
• Address lines
• Data lines

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Internal Bus Types

• parallel communications
• IDE (Integrated Drive Electronics)
• Hard drives, CD-ROM
• 16-bit parallel
• PCI (Peripheral Component Interconnection)
• network interface cards, video graphic adapters,
  etc.
• 32 or 64 bit parallel

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Internal Bus Types, contd.

• PCMCIA (Personal Computer Memory Card
  International Association)
• laptop expansion cards
• 16 bits parallel
• newer CardBus supports 32 bits
• SCSI (Small Computer System Interface)
• several generations

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PC Expansion Cards

• Controller cards - for disk drives and CD drives
• Sound cards - contain MIDI and I/O connections
• Graphics card - connects monitor and computer
• Network card - connects network resources
  together
• Modem card - connects computer to telephone
  system
• Game card - connects a joystick or other input
  devices to a computer

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Expansion Ports

• Parallel ports- connection to transmit 8 data
  bits at a time in parallel on eight separate data
  lines. Used mainly to send data to the printer.
  10 to 50 ft range.
• Serial ports (RS 232) - connection to transmit
  one bit of data at a time. Usually used for
  modems or for mice. Good for long distances.
• SCSI ports - support high transmission speeds and
  allow you to daisy-chain together up to seven
  devices on one port. A parallel interface used
  for printers, disk drives, CD-ROMs scanners.
• USB - Universal Serial Bus, an external bus
  standard that supports data transfer rates of 480
  Mbps. A single USB port can be used to connect up
  to 127 peripheral devices, such as mice, modems,
  and keyboards.
• Firewire 0r IEEE 1394, external bus rates of
  400 Mbps 63 devices