Transcript Chapter 1 Information Technology: Principles, Practices

Chapter 4
The Central Processor
and Memory
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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)
Definition (Continued)
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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)
•Arithmetic Logic Unit (ALU):
–part of the CPU
–performs arithmetic and logical operations.
• Logical Operations: • Arithmetic Operations:
– Addition
– Greater Than (>)
– Subtraction
– Less Than (<)
– Multiplication
– Equal To (=)
– Division.
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Memory
Definition
•
•
•
•
•
Primary Storage
Primary Memory
Main Memory
Internal Memory
RAM:
– Primary memory holds data temporarily,
– as the computer executes instructions.
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Memory
Definition (Continued)
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Memory
Memory 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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Memory
Memory 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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Memory
Memory 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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Memory
RAM and ROM
• ROM
• RAM
– Read-only Memory
– Random-access Memory
– Memory is persistent even – Read or Write
if computer is turned off
– Memory is lost when
– Computer BIOS is stored
computer is turned off
on ROM chip
– Random-access  any
– BIOS (Basic Input Output
part of the memory can
System) need so
be access in constant
computer can boot
time.
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Memory
Flash 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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Memory
RAM, ROM and Flash Memory
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Memory
Definition
• 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 Unit
Definition
• 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 Unit
Processor 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 Unit
Evolution of Intel Pentium Family of
Microprocessors
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Inside the System Unit
Intel 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 Unit
Evolution of Microprocessors for
Macintosh Computers
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Inside the System Unit
Other Microprocessor Chips
• AMD
• Digital Equipment Corp.
• Motorola
• MIPS Technologies
• Sun Microcomputers
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Inside the System Unit
Memory 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 Unit
Ports
• 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 Unit
Universal 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 Unit
Add-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 Unit
Plug 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 Sequence
The 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 Sequence
The Machine Cycle
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The Processing Sequence
Registers
• 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 Speed
Definition
• 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 Speed
Definition (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 Speed
Determining Processor Speed
• Four elements:
– System Clock
– Bus Width
– Word Size
– Available Memory
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Processor Speed
Determining 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 Speed
Determining 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 Speed
Determining Processor Speed
(Continued)
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Processor Speed
Determining 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 Speed
Determining 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 Speed
Determining 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 Speed
Determining Processor Speed
(Continued)
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Processor Speed
Determining 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 Speed
Determining 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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Processor Speed
Determining Processor Speed
(Continued)
• Grid Computing:
– A process that harnesses idle time on a
computer
– uses multiple computers to provide
processing for an application that needs more
speed and capability
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