2011年2月27日星期日

Chapter 6 The System Unit

Chapter 6 The System Unit


l  Speed, capacity, and flexibility determine the power of microcomputers.


l  Knowledge of a computer’s power allows you to make good buying decisions and to determine if your current system will run new applications.


l  Competent end users need to understand the basic principles of how microcomputers are put together. These principles will be covered in this chapter.


System Unit Types


l  Desktop System Units


l  Media Center System Units


l  Notebook System Units


l  Tablet PC System Units


l  Handheld Computer


Electronic Data and Instructions


Two-state system or Binary System:


l  Off/on electrical states
l  Characters represented by 0s (off) and 1s (on)
l  Bits
l  Bytes
      
Character Coding Schemes


Three types of binary coding schemes
l  ASCII - American Standard Code for Information Exchange
l  EBCDIC - Extended Binary Coded Decimal Interchange Code
l  Unicode – handles languages with large numbers of characters






Microprocessor Chips


  A microprocessor incorporates most or all of the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC, or microchip).


Microprocessor Chips
•          Central Processing Unit (CPU)
•          Two Basic Components
–        Control unit
–        Arithmetic-logic unit (ALU)
•          Chip capacities are expressed in word sizes
•          Two Recent Significant Developments
–        64-bit processors
•          Have become standard for most of  today’s desktop and laptop computers
–        Multi-Core Chips
•          Can provide two separate and independent CPUs
•          Parallel processing


Memory
•       Types of memory chips
l    Random-access memory (RAM) is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order (that is, at random).
l    Read-only memory, a type of storage media which is used in computers and other electronic devices.
l    Flash memory is used for a wide  of range of applications, If changes are made to the computer system, these changes are reflected in flash memory


Expansion Slots and Cards
•       Allow for new devices to
be added
–      Open architecture
–      Slots provide for expansion
•       Expansion cards are
also called …
–      Plug-in boards
–      Controller cards
–      Adapter cards
–      Interface cards




Power Supply
•      Computers require direct current (DC)
•      DC power provided by converting alternating current (AC) from wall outlets or batteries
•      Desktop computers use power supply units
•      Notebooks and handhelds use AC adapters


A Look to the Future
•          Wearable computers
•          Send and receive email while jogging
•          Maintain your personal schedule book
•          Remember the names of people at a party












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