A Guide to PC Hardware Maintenance and Repair

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A Guide to PC Hardware Maintenance and Repair

• Michael W. Graves

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A Guide to PC Hardware Maintenance and Repair
Chapter 1 PC Basics
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Objectives

• Before we get started, we need to define a few
  basic terms
• Well go over the basic computer model
• The basics of binary will be introduced
• Youll get an introduction to PC architecture

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• Definition of a computer Any device that can do
  the following
• Accept input of user data
• Process user data and instructions to accomplish
  a specific task
• Provide output of the results of that processing
  for user access

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• The Basic Computer Model
• Processing
• RAM
• I/O
• Storage

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• Processors are fairly limited in scope
• Basic Instruction Set
• Basic Capabilities
• The Three Cs of Processing
• Calculate
• Copy
• Compare

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• Calculation
• CPU Processes
• Add, subtract, multiply and divide
• Only full-integer notation
• Anything beyond that requires additional hardware
  assistance
• Math Co-processor
• Floating Point Unit

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• Copying
• happens many times with each instruction that is
  processed
• between registers in the CPU
• between devices in the system
• between different addresses in memory

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• Comparing
• every time data is copied, the original data set
  must be compared to the new data set
• when data is being sorted, values in the database
  must be compared to the sort string
• when data sets are being searched the database
  must be compared to the search string

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• The Purpose of RAM
• short term storage of instructions and data
• faster access to data for the CPU
• The Limitations of RAM
• Volatile if power is lost, data is gone
• Capacity Limitations CPUs can only address so
  much RAM

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• Input/Output (I/O)
• Programs are useless without user input
• The effects of processing are useless if the user
  cant retrieve it
• Different devices have different procedures for
  I/O operations

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• Storage
• When the system goes off, some user data must
  remain.
• Data must be moved from system to system
• A place for temporary files used by applications
  and the OS

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• Typical Input devices
• Keyboard
• Mouse
• Trackball
• CD-ROM
• Scanner

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• Typical Output Devices
• Sound cards
• Monitors
• Printers

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• Typical Input/Output Devices
• Disk drives
• CD-R and CD-RW drives
• Tape Drives
• Touchscreen Monitors

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• The basics of binary
• Based on the theories of George Boole
• 0 or 1
• Yes or No
• On or Off
• Open or Closed

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• Some terms in binary
• bit a single 0 or 1
• byte 8 0s or 1s creating a character
• nibble 4 0s or 1s creating half a character
• Word 2 to 4 bytes
• Dword double-word

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• Each bit in a byte has a relative value

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• In that byte is a Least Significant Bit (LSB) and
  a Most Significant Bit (MSB)

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• Some applications or operating systems transmit
  data least significant bit first.

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• Other applications or operating systems transmit
  data most significant bit first.

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• Introducing Hexadecimal
• Four bits are used to make a character.
• Four bits can create as many as sixteen
  characters.
• The numeric characters 0 through 9 and the
  alphabetic characters A through F represent each
  character.
• A lower-case h at then end of a string indicates
  hexadecimal notation.

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• Data Communications
• Serial bits of a byte follow one another along a
  single wire in single file.
• Parallel each bit in a byte travels on a
  separate wire.
• Most data transfer inside the system is parallel.
• Data transfer from the inside to the outside can
  be either serial or parallel.

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• Modes of Serial Communication
• Asynchronous
• A single byte of data with a starting delimiter,
  an ending delimiter and (sometimes) parity makes
  up the data package.
• Data is thrown out on the wire and we hope it
  gets there.
• Synchronous
• Larger quantities of data are bundled in packets
  with headers and trailers to control data
  transfer
• Sessions are set up between devices and receipt
  of data is acknowledged.

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• PC System Architecture
• Follows the basic computer model
• Consists of five primary busses
• Just what is a bus?
• Any path that data takes to get from one location
  to another.
• While the term bus is used in a plethora of
  ways, there are five primary system busses.

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• The Five Busses
• The CPU Bus
• The Address Bus
• The Local Bus
• The I/O Bus
• The Power Bus