The Components Of The System Unit

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The Components Of The System Unit
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Chapter 4 Outline

• Types of Computers
• System Unit
• Mother Board
• Processor
• Data Representation
• Memory
• Adapter Cards, Ports, Buses
• Processor Numbers

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Types of Computers

• Supercomputer
• Mathematically intensive applications military,
  scientific data
• Mainframe Computer
• Large corporations with large, centralized DB
  processing
• Midrange Computer(eg. Mini-computer server)
• Handles processing for an organizational unit or
  a smaller company
• Used as front-end processor for mainframes
• Microcomputer
• Desktop, Laptop, notebook
• Personal Digital Assistant (PDA)
• Smart Card

Cray X1Supercomputer
IBM zSeries 900 Mainframe
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The System Unit

• Case that contains electronic components of the
  computer used to process data (aka the chassis)

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Components of the System Unit

• Processor
• Memory
• Adapter cards
• Ports
• Drive bays
• Power supply

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The Motherboard

• Main circuit board in system unit
• Also called system board

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CPU - Central Processing Unit
Interprets and carries out basic instructions
that operate a computer also called the
processor
CPU
Arithmetic logic unit (ALU) performs arithmetic,
comparison, and logical operations
Arithmetic Logic Unit (ALU)
Control Unit
Control Unit directs coordinates operations
in computer
Memory
InputDevices
OutputDevices
Data
Information
Regardless of type, all computers have a
processor.
StorageDevices
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CPU - Machine Cycle
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CPU - System Clock

• Controls timing of all computer operations
• Generates regular electronic pulses, or ticks,
  that set operating pace of components of system
• Each tick is a clock cycle
• Pace of system clock is clock speed
• Most clock speeds are in the gigahertz (GHz)
  range (1 GHz one billion ticks of system
  clock per second)
• Processor speed can also be measured in millions
  of instructions per second (MIPS)

• The faster the processor, the more expensive the
  computer.

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CPU - Comparison

• For IBM-compatible PCs
• Intel - Celeron, Pentium, Xeon, Itanium
• AMD Athlon, Sempron, Opteron
• For Apple Macintosh or Power Macintosh
• Motorola
• IBM

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Data Representation Bit

• Most computers are digital
• It uses a Binary System
• Has 2 states ON or OFF
• represented by 2 digits 0 and 1, called Bits
• Bit - short for Binary digits

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Data Representation Byte

• Byte
• Eight bits grouped together as a unit
• Provides enough different combinations of 0s and
  1s to represent 256 individual characters
• Numbers, Uppercase/Lowercase letters, Punctuation
  marks

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Coding Schemes to Represent Data
A EBCDIC 11000001 ASCII 01000001
ASCIIAmerican Standards Code for Information
Interchange 8bit ? 256
EBCDICExtended Binary CodedDecimal Interchange
Code 8 bit ? 256

• Unicode
• coding scheme capable
• of representing allworlds languages16 bit ? up
  to 65,536

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Coding Schemes to Represent Graphics
Vector
Bitmap
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Memory

• Electronic components that store instructions,
  data, and results
• Consists of one or more chips on motherboard or
  other circuit board
• Each byte stored in unique location called an
  Address
• Types
• Volatile Memory
• Random Access Memory (RAM)
• Cache
• Nonvolatile Memory
• ROM
• Flash Memory
• CMOS

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Memory Storage Units
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RAM
Most RAM is volatile, it is lost when
computers power is turned off
Memory chips that can be read from and written
to by the Processor
Also called main memory or primary storage
The more RAM, the faster the computer responds
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RAM

• RAM may contain
• Operating system instructions
• Programs
• Data

• How much do you need?
• Software packages typically indicates RAM
  requirements
• For optimal performance, you need more than
  minimum specifications

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Two Types of RAM
Used for special applications such as cache
Static RAM (SRAM)
Dynamic RAM (DRAM)
Faster and more reliable than DRAM chips
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Memory Location

• Resides on small circuit board called a Memory
  Module
• Memory Slots on motherboard hold memory modules

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What is cache?

• Helps speed computer processes by storing
  frequently used instructions and data
• Also called memory cache

• L1 Cache - built into processor (8-128Kb)
• L2 Cache- slower but has larger capacity
  (64Kb-4Mb)
• Advanced Transfer Cache- Built-in L2 Cache -
  faster, located directly on CPU chip

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ROM (Read Only Memory)
Memory chips that store permanent data and
instructions
Nonvolatile memory, it is not lost when
computers power is turned off
ROM chips are called FirmwareManufactured with
permanently written data, instructions, or
information
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Flash Memory

• Nonvolatile memory that can be erased
  electronically and reprogrammed
• Used with PDAs, digital cameras, digital cellular
  phones, music players, digital voice recorders,
  pagers

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CMOS
Used in some RAM chips, flash memory chips, and
other types of memory chips
Complementary metal-oxide semiconductor memory
Uses battery power to retain information when
other power is turned off
Stores date, time, and computers startup
information
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Memory Access Time

• Amount of time it takes processor to read data
  from memory
• Measured in nanoseconds (ns), one billionth of a
  second
• It takes 1/10 of a second to blink your eye a
  computer can perform up to 10 million operations
  in same amount of time

Hard Drive
Memory
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Expansion Cards

• Expansion (Adapter) Card
• Enhances the functions of the system unit or
  provides connections to external devices called
  peripherals

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Expansion Slots

• Expansion Slot
• An opening, or socket, on the motherboard that
  can hold an adapter card
• With Plug and Play, the computer automatically
  configures cardsand other devices as you
  install them

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PC Cards / Flash Memory

• A PC card adds memory, sound, modem, and other
  capabilities to notebook computers
• A flash memory card allows users to transfer data
  from mobile devices to desktop computers
• Hot plugging allows you to insert and remove
  cards while computer is running

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Ports

• Port
• connects external devices to system unit
• Connector
• joins cable to peripheral
• Available in one of two genders male and female

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Serial Ports vs. Parallel Ports

• Transmits 1 bit at a time

• Transmits 1 bit of data at a time

• such as a printer
• but cannot reliably send data more than 20 feet.
  

• Connects slow-speed devices, such as mouse,
  keyboard, modem

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USB Port

• Universal Serial Bus
• can connect up to 127 different peripherals
  together with a single connector type
• PCs typically have 2-4 USB ports
• USB 1.1 ? 12 Mbps
• USB 2.0 ? 480 Mbps (High-Speed USB)
• USB Hub

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Special-purpose ports

• Allow users to attach specialized peripherals or
  transmit data to wireless devices
• digital video cameras, color printers, scanners,
  disk drives

• FireWire port
• MIDI (Musical Instrument Digital Interface)
  port
• SCSI (small computer system interface) port
• IrDA (Infrared Data Association) port
• BluetoothTM port

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Buses

• Channel that allows devices inside computer to
  communicate with each other
• What is transferred?
• Data Bus transfers data
• Address Bus transfers address in memory
• How much is transferred?
• Bus width - determines number of bits transmitted
  at one time
• Today 64-bit bus

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Buses
System Bus aka Front Side Bus (FSB) connects
processor to main memory
Expansion Bus connects processor to peripherals
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More on Processors Processor Numbers
Before
Now
Intel Pentium 4 Processor 3.4 Ghz with HT
Technology
Intel Pentium 4 Processor 650 with HT
Technology
which includes Clock Speed 3.4 GHz Front
Side Bus 800 MHz Level 2 Cache 2 Mb
Processor Numbers are used for comparisons within
a Processor Family (but not across Processor
Families)
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More on Processors Intels Dual Core Processor

• Demo
• CPU Comparison

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