Processor

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Processor

• Central Processing Unit (CPU)
• Primary storage (RAM)

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The Central Processing Unit (CPU)

• What is a CPU?
• The Brain of a computer, the one that does all
  the hard work.
• Accepts data, processes all the data and sends
  the results to memory

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Elements of CPU

• Arithmetic /Logic Unit
• the calculator of the computer ----gt
• does the actual arithmetic operations (,-,,/)
  decision making(ltgt)
• Control Unit
• the traffic cop
• controls and coordinates all operations within
  the CPU

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Registers

• Registers
• temporary high-speed storage units
• types accumulator, storage, instruction, address
• used by the Control unit and ALU to perform their
  functions

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BUS

• Bus
• provides transportation within the computer
• system of wires that connect internal components
  and carries data among and within them
• bus width

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Machine Cycle and Clock Speed

• Machine cycle
• internal electronic clock
• fixed number of clock pulses
• Clock speed
• Megahertz (Mhz) - million cycles per second
• common clock speeds (Mhz) - 50, 66, 75, 90, 100,
  120, 133, 150, 166, 200, 233, 266,333, 400
• criteria for CPU performance

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RISC vs. CISC Architecture

• CISC-complex instruction set computers
• complex and longer instructions
• need a micro-code in the CPU
• RISC-reduced instruction set computers
• fewer and simpler instructions
• directly processed in the CPU
• increased speed and grater throughput

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Architecture

• Motherboard - a large board containing the CPU,
  ROM, RAM
• System bus
• elements on motherboard are connected through
  metal lines carrying bit streams
• bus width 8bits, 16 bits, 32 bits, 64 bits
• Expansion slots

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CPU-What we already know?!?

• Intel Chips
• 8088 - (1979)
• 80286, 80386, 80486, 80586 (Pentium), Pentium Pro
  (P6), Pentium II (MMX)
• SX(no math co-processor), DX (with math
  co-processor),
• DX-2 double clock speed, DX-4 triple clock speed

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Popular Intel Chips
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Primary Storage

• RAM or Main Memory
• Stores instructions data to be processed by CPU
• Read-write memory
• Limited capacity - 640 KB Extended
• typically varies between 2 and 128 MB
• Temporary storage - volatile
• data lost with the loss of power

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Primary Storage(continued)

• Cache memory (L1 L2)
• very fast and close to CPU
• stores frequently used data and instructions

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Primary Storage(continued)

• ROM (read-only memory)
• nonvolatile
• provided by manufacturer
• permanently stored data for OS or applications
• PROM (programmable read-only memory)
• initially blank chip, later programmed on
• special-purpose programs as graphics and games
• EPROM (erasable PROM)
• erased by ultraviolet light
• EEPROM erased by electric pulses (software)