james tam introduction to hardware concepts covered units of measurement processors memory input and...
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James Tam
Introduction to hardware
Concepts covered
•Units of measurement
•Processors
•Memory
•Input and output
•Storage
•Peripherals
James Tam
Basic units of measurement
Bit
•binary digit
•smallest unit of measurement
•two possible values
Byte
•8 bits
Word
• The number of adjacent bits that can be stored and manipulated as a unit
•32, 64 for home computers, 128 for the most powerful
James Tam
Large units of measurement (storage size)
Note: use powers of two because computer storage (bytes) are based on the basic unit (bit).
~ 20 million four-drawer filing cabinets full of text
Kilobyte (kB) – a thousand bytes (1,024 = 210)
Megabyte (MB) - a million (1,048,576 = 220)
Gigabyte (GB) – a billion (1,073,741,824 = 230)
Terabyte (TB) – a trillion (1,099,511,627,776 = 240)
Petabyte (PB) – a quadrillion (1.125899906843e+15 = 250)
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Small units of measurement (speed)
millisecond (ms) – a thousandth of a second (1/1,000 = 10-3)
microsecond (μs) - a millionth of a second (1/1,000,000 = 10-6)
nanosecond (ns) – a billionth of a second (1/1,000,000,000 = 10-
9)
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What is hardware?
Hardware includes the physical components of a computer system e.g., a monitor, keyboard, mouse and the computer itself.
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Processor speed
Determined by many things
•Type of processor
•Clock speed (as measured in Hertz e.g., MHz, GHz)
* But also consider the rest of the computer!
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Relationship between clock speed and times between pulses
Examples
1 Hz = 1 pulse is sent out each second (1 second passes between each pulse)
10 Hz = 10 pulses are sent out each second (0.1 seconds passes between each pulse)
:
25 MHz machine = 25 million pulses sent out each second (0.000 000 04 seconds between each pulse or 40 ns between pulses)
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Some common types of processors
Intel processors (usually run some version of MS-Windows)
Type of processor Clock speed
Celeron 500 MHz – 1.3 GHz
Pentium III 650 MHz – 1.2 GHz (1200 MHz)
Pentium IV 1.4 GHz (1400 MHz) – 2.2 GHz (2200 MHz)
PowerPC processors in Apple computers
Type of processor Clock speed
G3 500 MHz – 700 MHz
G4 733 MHz or 867 MHz
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CISC processors and RISC processors
CISC (Complex Instruction Set Computers
•e.g., Pentium; 68000, 68020…(old Apple computers)
RISC (Reduced Instruction Set Computers)
•e.g., PowerPC (new Apple computers)
Difference
•Instructions on RISC computers are simpler?
•Architecture differs between the processors.
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2) ROM (Read only memory)
You can read but not change the contents
Contents written to (burnt) by special equipment
Non-volatile
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Types of ROM
•ROM
•PROM
•EPROM
•EEPROM
•Flash Memory (e.g., a computer BIOS, memory for game consoles)
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3) Cache memory
Stores less than RAM but much faster
Can be either part of the processor (L1) or separate from it (L2)
Both are much faster than regular memory RAM
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Output devices
Displays information from the computer to the a person.
Computer to a person
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2) Monitor quality (resolution)
Columns of pixels x Rows of pixels
Col 1, Row 1
Col 2, Row 1
Col 3, Row 1
… Col [c], Row 1
Col 1, Row 2
Col [c], Row 2
Col 1, Row 3
Col [c], Row 3
: :
Col 1, Row [r]
Col 2, Row [r]
Col 3, Row [r]
… Col[c], Row[r]
James Tam
3) Monitor quality (Color depth)
The number of possible colors that can be displayed for each pixel.
e.g. monochrome (single color) 01
2 possible values
Uses up 1 bit of space
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Tradeoff between resolution and color depth
There is a limit for both
e.g. 16 bit color at 1600 x 1280 = 2 bytes per pixel * 1600 columns of pixel * 1280 rows of pixels = 4.096 MB
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4) Monitor quality (dot pitch)
Dot pitch is the distance between the center of each color dot (mm)
3 guns form 1 color dot
dot pitch
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Refresh rate of monitors
How fast the screen is redrawn
Again there is a tradeoff between resolution and refresh (70 Hz / 70 times per second is usually a good minimum)
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Types of monitors
1) CRT – use three electron guns (shown on previous slides)
2) LCD (flat screen) – use a liquid crystal display
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CRT’s vs. LCD’s
CRT
•Cost less for the same quality
•Sharper images possible (more colors, higher resolution)
•Can view images from any angle
LCD
•Less eye strain (no flicker and less glare)
•Uses less space
•Use less power
•Weigh less
•Lower radiation
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What is the difference between storage and memory?
Memory
•keep the information for a shorter period of time
•faster
•more expensive
•“scrap paper for the computer”
Storage
•the information is retained longer
•slower
•cheaper
•“file cabinet for the computer”
James Tam
1) Optical CD & DVD
CD ROM (read only)
CD-R: needs a CD-burner to create (record) to a CD
•Cheap and portable storage of a lot of data (650 MB)
CD-RW: can write and erase CD to reuse it (rewritable)
DVD-ROM (DVD-ROM/RW’s) – stores even more info
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1) CD’s and DVD’s (recording information)
Use special compounds
By default the surface of the CD is reflective
CD
A weak laser (read laser) is shot at the disc to determine the reflective portions
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1) CD’s and DVD’s (recording information)
A strong laser (write laser) heats selected parts of the disc.
CD
The melted part no longer reflects light
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1) CD’s and DVD’s (erasing the information)A laser (erase laser) heats selected parts of the disc (not quite as hot as a write laser).
CD
The re-melted part reflects light again
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2) Magnetic drives (hard drives)
Stores a lot of information (~20 GB – 80 GB)
Slower than memory (but faster than other forms of storage)
Spin rate (5400, 7200, 10000 rpm)
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2) Magnetic drives (floppy)
Pros
•Portable
•Cheap
Cons
•Slow
•Low storage capacity (1.44 MB)
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2) Magnetic drives (structure)
A cylinder (a bunch of sectors on different platters, one on top of the other – hard drives only)
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Buses
Connects together the different parts of the computer.
Used for the transfer of information.
Width determines its speed
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PortsAre used to connect the computer to outside devices
Serial, parallel
•Ports on older computers (slower, 1 port to one device)
USB (Universal serial bus)
•Standard on newer computers (faster, up to 127 devices on 1 port)
Firewire
•Fast (video)
James Tam
How inkjet printers work.Use a series of nozzles to spray drops of ink directly on the paper
Printer heads
Ink nozzles
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Characteristics of Inkjet printers
Printer costs less (black and white ~ $70.00, color ~$100.00+)
Cost per page is more
Slower
Text is lower quality, color pictures may be higher quality
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How laser printers work
Use a laser to produce patterns on an ink drum using static electricity
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Characteristics of Laser printers
Printers cost more (black and white ~ $300.00+, color ~$3000.00+)
Cost per page is less
Faster
Text is higher quality, color pictures may be lower quality
James Tam
SummaryImportant concepts
•What is hardware and what are common units of measurement used
•Processors – what do they do, what are their characteristics, types of processors
•Memory – what is it, types of memory
•What is the purpose of an input device, types of input devices
•What is an output device, types of output devices
•General characteristics of computer monitors
• Storage devices – different types and how they work
•Other parts of a computer (beyond the simple model) – motherboard, buses, ports
•Common peripherals (printers, scanners, cameras)