1 chapter 4 the central processor and memory. 2 the central processing unit (cpu) definition central...
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The Central Processing Unit (CPU)Definition
• Central Processing Unit (CPU) or Processor:– executes program instructions and – performs the computer’s processing
actions.
• Integrated Circuits/Chip/Microchip: – thousands or millions of transistors – placed on a small silicon chip.
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The Central Processing Unit (CPU)Definition (Continued)
• Transistor: – An electrical switch– can be in one of two states:
• open or • closed.
• Integrating: – The process of packing more transistors
onto a single chip.
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The Central Processing Unit (CPU)Control Unit
• Control Unit: – The part of the CPU– oversees and controls all computer
activities• Instructions:
– Low level actions to be carried out during• input• processing• output• storage• transmission.
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The Central Processing Unit (CPU)Arithmetic/Logic Unit (ALU)
• Logical Operations:– Greater Than (>)– Less Than (<)– Equal To (=)
• Arithmetic Operations: – Addition– Subtraction– Multiplication– Division.
•Arithmetic Logic Unit (ALU):–part of the CPU –performs arithmetic and logical operations.
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MemoryDefinition
• Primary Storage• Primary Memory• Main Memory• Internal Memory• RAM:
– Primary memory holds data temporarily, – as the computer executes instructions.
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MemoryMemory Size
• Bit: – On or Off– 1 or 0
• 2 Bits: – Four different values: 00, 01, 10, 11
• 3 Bits: – Eight different values:– 000, 001, 010, 011, 100, 101, 110, 111
• Byte: – 8 bits– 256 different values– Approximately 200 printable characters.
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MemoryMemory Size
• Kilobyte (KB or K): – 1000 bytes– 500 word text file about 3-4K
• Megabyte (MB): – One million bytes.– Bitmap 800 X 600 X 24 bits 1.4 MB
• Gigabyte (GB): – One billion bytes.
• Terabyte (TB):– One trillion bytes.
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MemoryMemory Size (Continued)
• How much space?– Turing
• 1,000 home directories• average home directory size 250 MB
– Image • 2400 X 1800 resolution • 64,000 colors
– Database• 500,000 people• first name• last name• phone number
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MemoryRAM and ROM
• ROM – Read-only Memory– Memory is persistent
even if computer is turned off
– Computer BIOS is stored on ROM chip
– BIOS (Basic Input Output System) need so computer can boot
• RAM – Random-access Memory– Read or Write– Memory is lost when
computer is turned off– Random-access any
part of the memory can be access in constant time.
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MemoryFlash Memory
• Flash Memory: – Read and Write– retains it contents even when electricity is
turned off.– Currently used in
• Cell phones• Digital Cameras• iPods, MP3 players• Key chains
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MemoryDefinition
• Boot: – To turn on the computer system– let the built-in self-test run.
• Cold Boot: – turned on from an off state– CPU invokes the ROM BIOS boot program, which runs – the power-up – self-tests and– loads the operating system from disk storage.
• Warm Boot: – In a restart, the BIOS knows the system is already
running (data is written in a specific memory location checked by the BIOS) and skips the power-on test.
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Inside the System UnitDefinition
• Board: – A hardware device onto which chips and
their related circuitry are placed.
• System Board (Mother Board): – The hardware unit that houses a computer’s
processor, memory chips, ports, and add-in boards.
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Inside the System UnitProcessor Chips
• Microprocessor: – The smallest type of processor, with all of
the processing capabilities of the control unit and ALU located on a single chip.
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Inside the System UnitIntel Microprocessors
• Intel Celeron Processors– Does NOT have L2 cache, i.e., expensive
memory that speeds up performance• Intel Pentium Processors
– The Standard• Intel Xeon Processors
– Designed to work in pairs (dual processors)• Intel Itanium Processors
– 64-bit processor
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Inside the System UnitOther Microprocessor Chips
• AMD
• Digital Equipment Corp.
• Motorola
• MIPS Technologies
• Sun Microcomputers
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Inside the System UnitMemory Chips
• Single In-line Memory Module (SIMM): – A multiple-chip memory card inserted as a
unit into a predesignated slot on a computer’s system board.
• Installed Memory: – The amount of memory included by a
computer’s manufacturer on its memory board.
• Maximum Memory: – The most memory that a processor can
hold.
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Inside the System UnitPorts
• Port: – A connector through which input/output
devices can be plugged into the computer.
• Expansion Slot: – A slot inside a computer that allows a user
to add an additional circuit board.
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Inside the System UnitUniversal Serial Bus
• Universal Serial Bus (USB): – A general purpose port that can connect up
to 128 devices, and also hot swappable, – meaning that devices can be plugged in or
unplugged without having to shut down or reboot the system.
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Inside the System UnitAdd-In Boards
• Add-in Boards: – A board that can be added to a computer to
customize its features and capabilities.
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Inside the System UnitPlug and Play
• Plug and Play: – The ability to install devices into a computer
when the computer itself makes any necessary internal adjustments.
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The Processing SequenceThe Machine Cycle
• Machine Cycle: – The four processing steps: fetch, decode,
execute, and store.• Instruction Cycle (I-cycle):
– The first two steps (fetch and decode), in which instructions are obtained and translated.
• Execution Cycle (E-cycle): – The last two steps of the machine cycle
(execute and store), which produce processing results.
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The Processing SequenceRegisters
• Register: – temporary storage built into the processor– can move data and instructions more
quickly than main memory can• Four types:
– Storage Registers– Address Registers– Accumulators– General-Purpose Registers
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Processor SpeedDefinition
• Millisecond: One thousandth of a second
• Microsecond: One millionth of a second.
• Nanosecond: One billionth of a second.
• Picosecond: One trillionth of a second.
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Processor SpeedDefinition (Continued)
• Millions of Instructions per Second (MIPS): – The number of instructions the processor
can execute per second – a measure of processor speed.
• Megaflops: – Millions of floating point operations per
second – a measure of how many detailed arithmetic calculations the computer can perform per second.
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Processor SpeedDetermining Processor Speed
• Four elements: – System Clock– Bus Width– Word Size– Available Memory
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Processor SpeedDetermining Processor Speed (Continued)
• System Clock: A circuit that generates electronic impulses at a fixed rate to synchronize processing activities.– Megahertz (MHz): Millions of electric pulses
per second – a measure of a computer’s speed.
– Gigahertz (GHz): Billions of electric pulses per second.
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Processor SpeedDetermining Processor Speed (Continued)
• Bus Width– Input/Output (I/O) bus: A bus (electronic
circuit) that moves data into and out of the processor.
– Data Bus: A bus that moves data between the central processor and memory.
• Word Size– Word: The number of bits a computer can
process at one time.
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Processor SpeedDetermining Processor Speed (Continued)
• Cache Memory: – A form of high-speed memory that acts as a
temporary holding/processing cell.• Coprocessors:
– A special-purpose chip mounted on a processor board; it is designed to handle common functions quickly and efficiently
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Processor SpeedDetermining Processor Speed (Continued)
• CISC: – Complex Instruction Set Computing– Intended to be an improvement– Complex instructions require main memory
• RISC:– Reduced Instruction Set Computing– A return to the old way– Compact instructions need only registers
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Processor SpeedDetermining Processor Speed (Continued)
• Pipelining: – A computer starts processing a new
instruction as soon as the previous instruction reaches its next step in the processing cycle.
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Processor SpeedDetermining Processor Speed (Continued)
• Sequential Processing: – Processing in which the execution of one
instruction is followed by the execution of another.
• Parallel Processing: – For computers will multiple processor– computer handles different parts of a program
by executing instructions simultaneously.
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Processor SpeedDetermining Processor Speed (Continued)
• SIMD– Single Instruction/Multiple Data method– A parallel-processing method – executes the same instruction on many data
values simultaneously.• MIMD
– Multiple Instruction/Multiple Data method– A parallel-processing method– connects a number of processors that run
different programs or parts of a program on different sets of data.
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