Major Hardware Components of a Computer System by dblock21

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									    Major Hardware Components of
         a Computer System
•   Central Processing Unit
•   Auxiliary Storage
•   Input Devices
•   Output Devices
        Central Processing Unit
• Arithmetic/Logic Unit (ALU): processes data
  arithmetically (addition, subtraction,
  multiplication, division) or logically (greater than,
  less than, equal to)
• Control Unit: works with the operating system to
  move data between auxiliary storage and main
  memory; and between main memory and the ALU
• Main Memory: contains both program instructions
  and the data that is required.
• A single machine can have multiple CPUs to
  share processing tasks (co-processors,
  multiprocessing), but each CPU can execute only
  a single task.
       Inside the System Unit
• Main component: motherboard
  – Circuit board that “houses” integrated circuits
    (microscopic elements … wires, transistors,
    etc…) required to make the digital pulse flow
    inside of the computer. Pulses flow from
    component to component via the “bus”
  – Some microcomputers contain a special local
    bus (VESA or PCI) which increase data transfer
    rates to the display and/or storage devices
            Motherboard (cont.)
– Attachments to the motherboard include:
   • Main Memory: types of main memory include:
       – RAM - temporary (includes virtual memory storage). Include RAM
       – ROM - permanent
       – CMOS - semipermanent battery powered
           » Memory chips attach with either a DIP (dual inline pin - old PCs)
             or as a SIMM (single inline memory module) board
       – When add main memory, make sure add-on chips are compatible
   • Real time clock (current date and time)
   • Microprocessor or CPU (central processing unit)
       – Control Unit: traffic cop portion of the CPU
       – ALU: arithmetic logic unit processes all math and logical operations
         performed by the computer
       Motherboard (cont.)
• Expansion slots/add on boards - allow “cards” that attach
  various peripheral devices to the motherboard
    – monitors, hard drive, internal fax/modem, network cards,etc
    – PCMCIA slots: special slots developed for laptops to attach
      devices and add on RAM
• Expansion devices may provide an external “port” which you
  connect a cable to. Device ports will either be from an internal
  or external bay in the system unit.
    – Serial Port: transmits data one bit at a time (modem)
    – Parallel Port: transmits 8 bits simultaneously (printers, backup
      devices, etc.)
    – SCSI Port: allows several devices to be chained together and
      connected through a single SCSI (small computer system
    – MIDI Port: musical instrument digital interface
                 Main Memory
• Random Access Memory (RAM): allows data
  and instructions to be accessed randomly from any
  memory location (address). Primary storage.
   – Volatile - lost when power is turned off
• Read Only Memory (ROM): usually contains
  programs that help the computer system operate:
   – can only be read: cannot be written to or altered by the
     user (usually)
   – ROM is not volatile
                   Main Memory
• Data and instructions are stored as BITS (binary
  digits). Everything from our world is translated
  into a computer recognizable format called binary
  (zeros or ones)
   – The combination of binary digits represents our letters
     or numbers. One character represented is equal to a
• Memory capacity is measured in bytes. Today’s
  most common measurement is megabytes
   Kilo = 1,000 (KB) Thousand
   Mega = 1,000,000 (MB) Million
   Giga = 1,000,000,000 (GB) Billion
• Bytes are composed using either the ASCII
  coding system (7 bits = character) or EBCDIC (8
  bits = character)
       Microprocessor Families

• Intel (IBM) and Motorola (Macintosh
  68000) two main manufacturers
• Microprocessors are “families” - upward
  increases in speed (early SX vs DX chips)
• Increase in bus capacity indicates a new
            The Boot Process
• When you turn your computer on, the following
  activities happen:
  – Power is sent to the internal fan and the motherboard
  – The boot program stored inside of ROM activates
  – The Power-On Self-Test (POST)runs and tests required
    system components
  – The operating system/environment is loaded
  – Configuration and customization routines are executed
    which set your computer environment
   Input/Output Peripheral Devices

• Badge Reader                • SASD & DASD drives
• Bar-code Reader             • Printers
• Cartridge & cassette            – Page vs line or character
  drives                            printers
                                  – Impact vs nonimpact
• CD Rom
                              •   Plotter
• Digital camera
                              •   Robotics
• Digital tables & scanners
                              •   Speech synthesizer
• Keyboard, mouse, pens
                              •   VDT
                              •   Microforms
• Voice
• Touch screen
Required because main memory is limited, expensive
                  and volatile.
   • Sequential Access Storage Devices (SASD): data is stored
     in sequential order. Retrieval is also sequential.
      – Storage media is magnetic tape.
      – Supports batch processing environment
      – Excellent form of backup
   • Direct Access Storage Devices (DASD): data can be stored
     and retrieved randomly.
      – Storage capacity is referred to as density. How tightly
         packed data is on the disk.
      – DASD is required for transaction processing.
   • Memory capacity is measured in bytes. Today’s most
     common measurement is kilobytes, megabytes and gigabits.
         Printer Considerations

• Dot matrix - low price & inexpensive to
  operate. Lower quality. Impact - can print
  carbon forms. Color option. Slow.
• Ink jet - moderate price & better output.
  Color option. Nonimpact. Quieter.
• Laserjet - more expensive. Faster. High
  quality. Nonimpact.
         Display Considerations
• Screen size- diagonal measurement from corner to
  corner. Popular sizes are 14”, 15” and 17”
• Dot pitch - measure of image clarity. The smaller
  the dot pitch, the crisper the image or resolution.
• Video adapters/cards impact image resolution and
  display speed. Today, most monitors are Super
  VGA (1024 x 768)and use non-interlaced
  projection technology (flicker)
• Laptop - liquid crystal display (LCD). Passive
  matrix vs active matrix screen (display method
  which impacts image quality). Active matrix is
  much better but more expensive and can have

• Floppy Disk: removable DASD. Most common
  density is 1.44Mb.
• Hard Disk: usually don’t remove (but newer
  devices you can). Higher storage capacity than
  floppy disks. Faster access.
   – Winchester drive architecture is not removable.
   – Can be drives that have removable disk platters.
   – Optical disk: CD_ROM (read-only) Erasable optical
     disk is also available. WORM - write once, read many.
   – Flash memory: main memory on a card. Non volatile.
     PCMCIA card.
                 DASD cont.

• All data stored on DASD media is stored in pie-
  shaped sectors that determines how much data is
  moved into and out of main memory at a time.
• Virtual storage: operating system uses hard disk
  drive as an extension of main memory.
• Cache memory: operating system assumes that
  most data used by an application is accessed over
  and over again. Cache is a special area in main
  memory where such data is put instead of paging
  it back and forth to DASD.
               DASD cont
• WORM: write-once, read many. (CD
  ROM). Also have rewriteable CD ROM.
• Floptical Disk: optical storage capacities on
  floppy disk.
• DVD: Digital video disk
• Hierarchical Storage: use of many different
  types of DASD & SASD devices to achieve
  storage requirements.
          Other considerations:
• Desktop vs Laptop - expansion slots and
   – Port replicators vs docking station
   – Pointing device. Track ball, touch pad, erase point.
   – Power management & battery considerations (hot
• Multimedia devices - sound cards, speakers and
  MPC standards
• Bundled software
       Common File Types
• Data Files: files of information created when
  people use various types of software
• Executable Files: Types of systems files that are
  used by the computer to perform certain tasks.
  With some executable files (.exe., .com, .bat) you
  can initiate the processing while with others the
  computer initiates the process (.dll, .sys, .drv, etc.)
• You and your AUTOEXEC.BAT file.
          Anatomy of a Filename

• Rules for creating valid filenames
  (appropriate characters, length of names,
  etc.) depends on the operating system being
• Components of a filename consist of:
                                              File name from

   Drive Designation   C:/foldername/filename.ext
                        Folder/subdirectory          File extension
                               name                 supplied by the
                      File Storage
• Logical Storage:            • Physical Storage
How you perceive that data    How data actually
  is stored on an auxiliary     resides on your
  storage media                 auxiliary storage
File/disk directory
                              File Allocation Table
No indication of                (FAT)
  fragmentation               Fragmentation is normal
Measurements of Computer Power
• Clock speed: electronic pulses used to
  synchronize processing. Faster clock speeds result
  in more operations in a give amount of time.
  Measured in megahertz (MHz).
• Bus width: determines how much data can be
  transferred at any one time. 16 bit, 32 bit, 64 bit.
   – IBM’s Microchannel (MCA) Architecture vs EISA
     (open architecture)
• Word size: number of bits/bytes manipulated at
  once. Same as the bus width.
• Other determinants include main memory
  capacity, MIPs.
• This is not the same as throughput but it can affect

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