Introduction to Computers

1
Introduction to Computers

• Lesson 4A

2
Decimal Number System

• Called base 10 because 10 symbols are available

3
Binary Number System

• Computers function in base 2, or the binary
  number system, where there are only two values

4
Bit

• A combination of binary digit
• The smallest possible unit of data a computer can
  recognize or use

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Byte

• A group of eight bits

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Text Codes

• EBCDIC
• ASCII
• Unicode

7
CPU

• The CPU is the computers brain that
  manipulates data

8
CPUs Two Basic Parts

• Control unit
• Arithmetic logic unit

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Control Unit

• Manages all the computers resources

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Arithmetic Logic Unit

• Performs the CPUs arithmetic and logical
  operations

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Machine Cycle

• The completed series of steps the CPU takes to
  execute an instruction

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Machine Cycles Two Cycles

• Instruction cycle
• Execution cycle

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Instruction Cycle

• Fetching
• Decoding

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Execution Cycle

• Executing
• Storing

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Millions of Instructions Per Second (MIPS)

• The CPU performance measurement

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Pipelining

• Also called pipeline processing
• The control unit begins a new machine cycle
  before the current cycle is completed

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Memory

• Allows the CPU to store and retrieve data quickly

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Two Kinds of Memory

• Read-only memory (ROM) nonvolatile
• Random-access memory (RAM) volatile

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ROM

• ROM always holds the same data, for example the
  computers start-up instructions

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RAM

• RAMs job is to hold programs and data while they
  are in use
• RAM can change instantly

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Other Kinds of RAM

• Dynamic RAM (DRAM)
• DRAM Variations
• Static RAM (SRAM)

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Factors Affecting Processing Speed

• Registers
• Memory and computing power
• System clock
• The bus
• The databus
• The address bus
• Cache memory

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Bus Types

• Industry standard architecture (ISA) bus
• Local bus
• Peripheral component interconnect (PCI) bus
• Accelerated Graphics Port (AGP) bus
• Universal Serial Bus (USB)
• IEEE 1394 (FireWire)

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Data Transfer Rate

• The amount of data buses can transfer in a second
• Measured in megabits per second (Mbps) or
  megabytes per second (MBps)

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Cache memory

• Speeds processing by storing frequently used data
  or instructions in its high-speed memory

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Lesson 4A

• Transforming Data Into Information

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Review Questions

• What is the difference between a bit and a byte?
• What are the CPUs two basic parts?
• What is a machine cycle?
• What is the difference between ROM and RAM?