More on Computer Components
•
•
•
•
•
•
•
Computer switches
Binary number system
Inside the CPU
Cache memory
Types of RAM
Computer buses
Creating faster CPUs
NEXT
SLIDE
1
Digital Data: Switches and Bits
• Electronic switches:
– Vacuum tubes
– Transistors
– Integrated circuits
• Binary number system:
– Representing numbers
– Representing letters and symbols
ON
OFF
• ASCII
• Unicode
NEXT
SLIDE
2
Electronic Switches
• Non-mechanical devices in computers that
open and close circuits
• Types of electronic switches:
– Vacuum tubes
– Transistors:
• Semiconductors
– Integrated circuits
NEXT
SLIDE
3
Switches Representing Data
• The on/off state of a switch represents one
bit of data
OFF
ON
• Bit (binary digit):
– On = 1
– Off = 0
OR
0
= 1 bit
1
NEXT
SLIDE
5
The Binary Number System
• Number systems:
– Organized ways to
represent numbers
64
32
2x32
2x16
Binary
2 digits 10
0 and 1
Base
10 digits 0 through 9
16
8
4
2
2x8
1000 2x4
100 2x210 2x11
10x100
10x10
1
10x1
Base 10
=
1011001
5832
89
NEXT
SLIDE
6
Representing Letters and
Symbols
• American Standard Code for Information
Interchange (ASCII):
– 8 bits equal 1 byte
– 256 different combinations
– 1 byte equals an alphanumeric character or
A
B
C
b
a
symbol
• Unicode:
ON
OFF
– 16 bits equal 1 byte
– 65000 different combinations
– Used for all languages:
• English, Japanese, Chinese, etc.
Click here to view an
ASCII Code chart
NEXT
SLIDE
7
The CPU: Processing Digital
Information
• CPU components
• Types of CPUs
• What the CPU does:
– Machine cycle:
• System clock
• Cache memory
NEXT
SLIDE
9
The CPU
• Also known as a microprocessor or
processor
• Executes instructions
• Components include:
– Control unit
– Arithmetic logic unit (ALU)
– Registers
– Cache memory
NEXT
SLIDE
10
Types of CPUs
PROCESSOR
MANUFACTURE
R
TRANSISTOR
S
CLOCK
SPEED
Athlon XP
AMD
54.3 million
2.20 GHz
Athlon 64FX
AMD
106 million
2.4 GHz
Centrino
Intel
77 million
1.70 GHz
Itanium 2
Intel
410 million
1.50 GHz
Pentium 4
Intel
55 million
3.20 GHz
Pentium 4
Processor-M
Intel
55 million
2.60 GHz
PowerPC G4
Motorola
57 million
1.00 GHz
PowerPC G5
IBM
58 million
2.00 GHz
NEXT
SLIDE
11
The CPU’s Machine Cycle
• Also known as the processing cycle
• Fetch:
– The Control Unit searches cache memory and
then RAM for program instructions
– Instructions are moved to the Control Unit
• Decode:
– The Control Unit reads and prepares the
program instructions
Click here to view the
– The instructions are sent to the video
ALU“Inside the Chip”
• Execute:
by Intel
– The ALU performs the calculations
NEXT
SLIDE
12
The System Clock
• Located on the motherboard
• Controls the CPU’s processing cycles
• Clock cycle:
– Pulse or tick
• Clock speed:
– Number of pulses per second
– Measured in hertz (Hz)
NEXT
SLIDE
14
Cache Memory
• Small amount of memory located on the
CPU chip or near it:
– Level 1
– Level 2
• Stores recent or frequently used
instructions and data
• Used for quick access by the CPU
NEXT
SLIDE
15
RAM: The Next Level of
Temporary Storage
• Dynamic RAM (DRAM):
– Loses its electrical charge
– Needs to be refreshed
– SDRAM:
• Synchronous DRAM
– DDR SDRAM
• Double data rate SDRAM
– RDRAM:
• Rambus DRAM
• Static RAM (SRAM):
– Does not lose its electrical charge
– Faster than DRAM
NEXT
SLIDE
16
Memory and Size
•
•
•
•
•
Data stored in bytes.
Sizes:
1KB – 1 kilobyte means 1024 bytes
1MB – 1 Megabyte, approx. 1 million bytes
1GB – 1 Gigabyte, approx. a thousand
MBs. (1,000,000,000 bytes)
17
Buses: The CPU’s Data
Highway
• Bus:
– Electrical pathway used to move data
between components
– Local bus:
• Connects the CPU with the memory
– Expansion bus:
• Connects the CPU with peripheral devices
01100010
01001000
01110011
00100111
NEXT
SLIDE
18
Bus Performance
• Bus clock speed:
– Rate of speed data moves from one location
to another
– Measured in Mhz (millions of clock cycles per
second)
• Bus width:
– The number of bits of data moved on a bus at
any one time
– Measured in bits:
• 16 bits
• 32 bits
NEXT
SLIDE
19
Types of Expansion Buses
• ISA and EISA:
– Found on older computers
– Connects mouse, modem, and sound card
• PCI:
– Faster than ISA and EISA
– Found on modern computers
– Connects network, modem, and sound card
• AGP:
– Used for three-dimensional graphics
– Connects the graphics card and memory
NEXT
SLIDE
20
Making Computers Faster
• Pipelining:
– The CPU processes more than one
instruction at a time
Non-pipelined CPU
Instruction 1
Fetch
Decode
Execute
Store
Instruction 2
Fetch
Decode
Execute
Store
Pipelined CPU
Instruction 1
Fetch
Instruction 2
Decode
Fetch
Execute
Decode
Store
Execute
Store
Fetch
Decode
Execute
Store
Instruction 4
Fetch
Decode
Execute
Instruction 3
Store
NEXT
SLIDE
21
Making Computers Faster
• Dual processing:
– Two CPUs on the
same system
– Each processor
shares the workload
Dual processors
• Parallel processing:
– Network of
computers
– Each computer
works on a portion of
the problem
simultaneously
NEXT
SLIDE
22