Major Hardware Components of a Computer System

1
Major Hardware Components of a Computer System

• Central Processing Unit
• Auxiliary Storage
• Input Devices
• Output Devices

2
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.

3
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

4
Motherboard (cont.)

• Attachments to the motherboard include
• Main Memory types of main memory include
• RAM - temporary (includes virtual memory
  storage). Include RAM cache
• 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

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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 interface)
• MIDI Port musical instrument digital interface

6
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

7
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 byte.
• Memory capacity is measured in bytes. Todays
  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)

8
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
  generation

9
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

10
Input/Output Peripheral Devices

• Badge Reader
• Bar-code Reader
• Cartridge cassette drives
• CD Rom
• Digital camera
• Digital tables scanners
• Keyboard, mouse, pens
• MICR
• Voice
• OCR
• Touch screen

• SASD DASD drives
• Printers
• Page vs line or character printers
• Impact vs nonimpact
• Plotter
• Robotics
• Speech synthesizer
• VDT
• Microforms

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StorageRequired 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. Todays
  most common measurement is kilobytes, megabytes
  and gigabits.

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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.

13
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
  problems.

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DASD

• Floppy Disk removable DASD. Most common density
  is 1.44Mb.
• Hard Disk usually dont 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.

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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.

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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.

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Other considerations

• Desktop vs Laptop - expansion slots and
  capability
• Port replicators vs docking station
• Pointing device. Track ball, touch pad, erase
  point.
• Power management battery considerations (hot
  swap)
• Multimedia devices - sound cards, speakers and
  MPC standards
• Bundled software

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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.

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Anatomy of a Filename

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

File name from you
C/foldername/filename.ext
Drive Designation
File extension supplied by the program
Folder/subdirectory name
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File Storage

• Logical Storage
• How you perceive that data is stored on an
  auxiliary storage media
• File/disk directory
• No indication of fragmentation

• Physical Storage
• How data actually resides on your auxiliary
  storage media
• File Allocation Table (FAT)
• Fragmentation is normal

21
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.
• IBMs 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 throughput..