computer hardware and architecture 1. objectives: by the end of this session, the student will be...
TRANSCRIPT
Computer Hardware and Architecture
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Objectives:By the end of this session, the student will be able to:Name and define 5 categories of Computer ArchitectureShow how these categories inter-relateDefine the function of input devicesList and describe the operation of the input devices described in the courseDefine the function of output devicesList and describe the operation of the output devices described in the courseDefine Primary StorageList 2 types of primary storageList the two parts of the CPUDescribe the function of each part of the CPUList the factors that affect processor speedDescribe how each of these factors affects processor speedList the 3 operating modes of the Intel processorDescribe the traits of these modesDefine Secondary StorageList 2 types of secondary storage, give examples of eachList the 3 structures of magnetic secondary storageList 3 PC ports that perform both input and outputCompare and contrast these ports based on maximum data transfer speed, maximum number of concurrently attached devices
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Computer Systems
History
1642: Pascaline was invented by Blaise Pascal in 1642. The device is able to add two decimal numbers. Using ten's complement it is also possible to subtract. Pascal had started production of his calculator (about 50 machines were produced), but there was no interest, so he had to stop.
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Computer Systems
History
1671: First calculator with multiplication and division
1801: Joseph-Marie Jacquard’s loom- introduction of punch cards
1822: Analytical Engine invented by Charles Babbage
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Computer Systems
History
1939: Atanasoff-Berry Computer. First computer built with vacuum tubes.
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Computer Systems
History
1940: Prototype of the Bombe developed by Alan Turing (Enigma code)
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Computer Systems
History
1943: Mark I. Developed in the U.S., with the help International Business Machines IBM)
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Computer Systems
History
1944: Colossus, designed by Tommy Flowers was operational (Lorenz code)
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Computer Systems
History
1946: ENIAC developed to calculate missile trajectories originally. Computers began to achieve manageable size.
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Computer Systems
History
1951: UNIVAC, first commercially sold computer
1954: First completely transistorized computer
1963: DEC PDP-8
1971: Intel 4004, first true CPU
1975: Altair Sphere 8800, sold as kits to hobbyists
1977: Apple II, Commodore PET
1978: Atari 400 and 800
1981: IBM PC
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Computer Systems
Definition
A computer system is hardware that contains software to transform data into information. This transformation requires four aspects of data handling:
Input Processing Output Storage
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Computer Systems, Continued
Structure
A computer system can be though of as:
Hardware
ComputerSystem
Software
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Computer Architecture
Computer Architecture
The architecture of a computer can be broken down into 5 categories. These 5 categories interrelate with each other in a structured way.
Categories
The categories of the architecture of a computer system are:
Category... Purpose...Input A means to get data
into the computer systemOutput A means to get information
out of a computer systemMemory, or A place to hold data temporarilyPrimary Storage while it is being manipulatedProcessor A place to perform the
manipulations on the dataSecondary Storage, or A place to hold data andAuxilliary Storage software for longer periods of time
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Computer Architecture, Continued
Interrelation of Categories
The categories interrelate in the following way:
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Computer Systems
Diagram
This is a diagram of the elements of a computer system:
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Computer Systems
Diagram
This is a diagram of the elements of a computer system, inside the chassis:
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Input
Purpose
The purpose of input is to take data that is external to the computer system, and transform it into data that is internal to the computer system.
Some of the devices that perform this function are: Keyboard Mouse Barcode scanner Optical Mark Recognition (OMR) Optical Character Recognition (OCR) Hand-written characters Voice recognition Touch screens
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Input: Keyboard
Keyboard
The keyboard is probably the most common way to get data into a computer system.
What it does
A keyboard converts the keys pressed by the user into electrical patterns that represent the letter or symbol that was pressed on the keyboard.
Diagram
Below is a diagram of a keyboard, with different regions labelled:
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Input: Mouse
Mouse
The mouse has become a very popular means of providing input to a computer system.
What it does
The mouse is used to position a pointer over a symbol on the screen. The buttons on the mouse can then be used to perform a defined action.
Diagram
Below is a picture of a typical mouse:
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Input: Barcode scanner
Barcode scanner
Barcode scanners are a means to read some data (numbers and letters) very quickly and enter them into a computer system faster and more accurately than a human.
What it does
A laser is reflected off of a label consisting of different width lines and into a photocell. The electronics of the barcode scanner convert the patterns of light and dark into an equivalent keyboard character.
Diagram
Below are pictures of typical barcode scanner applications:
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Input: OMR
Optical Mark Recognition
Optical Mark Recognition (OMR) is another means to get data into a computer system faster and more accurately that a person.
Example
Common examples of the use of OMR are: the bubble-sheets used in tests old style computer cards
What it does
The OMR reader recognizes marks on paper based on their position and converts them into data that is meaningful to the computer system.
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Input: OMR, Continued
Diagram
Below is a picture of a computer card that reads 'WELCOME TO ICS124SB!':
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Input: OCR
Optical Character Recognition
Optical Character Recognition (OCR) is another way to quickly and accurately input data into a computer system, yet the data itself is also readable by humans.
What it does
The characters used in OCR are very structured. Again a laser is reflected off a label containing the characters and into a photocell. The electronics in the OCR reader convert the patterns into equivalent keyboard characters.
Diagram
Below are OCR symbols:
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Input: Hand-written characters
Hand-written characters
The complexity of computer systems and electronics has advanced to the point where hand writing can be recognized by the computer. The purpose of this is to eliminate transcribing hand-written forms into electronic format through data entry operators.
What it does
The hand-written word is scanned and the pattern of lines compared to 'model' characters. When a match is found, that character is sent as a keyboard character.
Diagram
Below are samples of hand-written characters and the rules to write them:
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Input: Voice recognition
Voice recognition
Is means to provide some convenience when entering data into a computer system.
What it does
The process of voice input is:
Stage Description1 The word is spoken2 The sound waves are picked up by the microphone,
and sent to the speech Recognition Board3 The speech Recognition Board converts the
waveform into a value that represents a word4 The value is compared against a 'dictionary' of words5 The closest match is sent to the computer system
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Input: Voice recognition, Continued
Diagram
Below is a picture of the process:
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Input: Touch-screens
Touch screens
Touch screens are a means to allow a user to simply choose among a list of predefined choices, and provide the selection to the computer system.
What it does
A grid of light beams are projected vertically and horizontally across the surface of a screen. When a finger interrupts a horizontal and vertical light beam, the position of the finger is known. This information is passed to the computer system.
Diagram
Below is a picture of a touch-screen installation:
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Output
Purpose
The purpose of output is to take information that is internal to the computer system, and transform it into information that is external to the computer system, and therefore available for the user to use.
Some of the devices that perform this function are: Monitor Dot-matrix printer Bubble-jet printer Laser printer Voice
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Output: Monitors
Monitors
Monitors are the most common means to display information to a user. When viewing information on a monitor, it is said to be in 'soft copy' format.
What it does
The monitor consists of a Cathode Ray Tube, or CRT, that projects a stream of electrons across the back of its screen. The electron beam sweeps back and forth from the top to the bottom of the screen. The back of the CRT has a phosphorous coating that glows when hit by the electrons.
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Output: Monitors, Continued
Attributes of a monitor
There are various attributes of monitors that need to be considered when comparing one monitor to another:
Attribute DescriptionScan rate How many times per second is the screen refreshed.
80-100 Hz is adequate (Hz = Hertz = cycles per second)Interlaced Odd numbered lines scanned, then even number lines
are scanned.Non-interlaced All lines are scanned one after another. This type of
Monitor will produce less flutter on rapidly changingGraphics.
Resolution The number of pixels on the screen. More is better.eg. (HxV) 800X600, 1024x768, 1280x1024
Dot pitch The distance between pixels. Less the better. eg. 0.26mmScreen size Measured diagonally. This is at best approximate.
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Output: Monitors, Continued
LCD Technology
LCD is an acronym for Liquid Crystal Display. The crystals are sandwiched between two layers of polarizing film, set at right angles. The natural twist of the crystals causes light passing through them to reorient its plane of vibration.
By passing an electric current though the crystals, the crystals will straighten out- losing their twist.
If the twist of the crystals causes the light to reorient itself by 90o, then it can get through the second polarizing film layer.
If the twist has been eliminated, the light is not reoriented (maintains its original plane of vibration), and fails to get through the second polarizing film.
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Output: Monitors, Continued
Light entering first polarizing film layer. The right-most light wave is blocked.
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Output: Monitors, Continued
Light passing through first polarizing film, top wave enters crystal that has an electric current applied, the middle wave missed a crystal, the bottom wave enters a crystal with its natural twist
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Output: Monitors, Continued
Only the wave that was reoriented by the crystal escapes, and will be visible.
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Output: Monitors, Continued
LCD Panels
There are three elements of a 'pixel' in an LCD screen:
Red
Green
Blue
By turning on combinations of the elements of a pixel, 256 colours are available
By altering the amount of light that gets through the backlit screen or reflective screen, 256 shades per element are possible, therefore 16 million colours are available.
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= White= Yellow= Red
= Blue= Green= Magenta
Output: Monitors, Continued
Diagram
Below is a picture of a monitor:
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Output: Dot-Matrix printers
Dot-Matrix printers
The dot-matrix printer is one of the early types of printers. They tend not to be used today as they are too noisy for an office environment. They do have uses when multiple copies need to be printed simultaneously. They typically do not print in colour. When sending output to a printer, it is referred to as a 'hard copy'.
What is does
The dot-matrix printer contains a 'print head' that passes between a ribbon and the paper. Contained in the print head is a matrix of pins that strike the ribbon against the paper in a pattern of a character. The pins in the print head can be arranged as 5x7, 9x9 or better.
Diagram
An example of how the character 'A' would be displayed on a 5x7 dot-matrix printer:
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Output: Ink jet printers
Ink jet printers
The ink jet printer is very popular due to its: lost cost high resolution (300dpi) reasonable print speed use of colour low noise
What is does
The ink jet printer sprays ink onto the paper to form the images of characters or graphics.
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Output: Ink jet printers, Continued
Diagram
Below is a picture of an ink jet printer:
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Output: Laser printers
Laser printers
The laser printer is a high end printer that provides: superior resolution (600dpi - 1200dpi) fast print speed Is capable of colour, if you are willing to pay the price
What it does
A laser is used to neutralize points on a positively charged drum inside the printer. As the drum passes by a toner cartridge, toner sticks to the neutral spots on the drum. The toner is then transferred to paper and heated to fuse it in place.
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Output: Laser printers, Continued
Diagram
Below is a picture of a laser printer:
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Output: Audio
Audio
The output of audio information can take two forms: Speech synthesis Music
Speech synthesis
There are two methods of speech synthesis: synthesis by analysis synthesis by rules
Synthesis by analysis uses pre-recorded words stored and retrieved when needed. This method is limited by the number of words that were pre-recorded.
Synthesis by rules uses a device that applies linguistic rules to create artificial speech. This method is not as natural sounding as using pre-recorded words, however it is not as restricted.
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Output: Audio, Continued
MusicMIDI (Musical Instrument Digital Interface) is a set of rules designed for recording and playing back music on digital synthesizers.
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Primary Storage
Purpose
The purpose of primary storage is to store data for a short period of time while it is being manipulated.
The term 'memory' is also used when referring to Primary Storage, however this term also includes forms of memory that are not Primary Storage.
Primary Storage, Continued
Types of memory
The types of memory are listed below: RAM (Primary Storage)
DRAMSRAMExternal cache
ROM (not Primary Storage)PROMEPROMEEPROM
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Primary Storage, Continued
Measuring memory
The smallest unit of memory is the byte. A byte can used to represent a single character or symbol. When evaluating memory size the following aggregates are also used:
KB - kilobyte = 1,024 bytes MB - megabyte = 1,048,576 bytes GB -gigabyte = 1,073,741,824 bytes
A typical modern home computer will have 512MB or more
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Primary Storage, Continued
RAM
RAM is an acronym for Random Access Memory. RAM is volatile, in that when power is removed from the circuit, the contents of RAM are lost.
SRAM
SRAM is Static RAM. When data is written to SRAM, it is retained by the memory without any further intervention by the computer system.
DRAM
DRAM is Dynamic RAM. When data is written to DRAM, it must be periodically refreshed or it will loose its contents.
DRAM may be slower than SRAM, however due to its size and cost, it is used in most PCs.
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Primary Storage, Continued
DRAM, Continued
This is a picture of DRAM:
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Primary Storage, Continued
External cache
Cache is a a small amount of memory, typically 512KB, that is very fast.
By keeping instructions or data that is frequently used or most recently used in cache memory, there is a chance that the processor will not need to access the slower RAM memory to process the next instruction.
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ROM
ROM
ROM is an acronym for Read Only Memory. ROM is non-volatile, in that when power is removed from the circuit, the contents of ROM are retained.
The data on ROM is written once, or the ROM is manufactured with the data already present.
PROM
PROM is Programmable ROM. This is a memory chip that is manufactured with no data, however it can be written to once.
EPROM
EPROM is Erasable PROM. The contents of the ROM can be erased by exposing the circuit to UV radiation for 20 minutes. The EPROM is now ready to have new data written to it.
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ROM, Continued
EEPROM
EEPROM is Electrically Erasable PROM. The contents of the ROM can be erased by sending an erase signal to the EEPROM circuit. The EEPROM is now ready to have new data written to it.
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Processor
Purpose
The processor, or Central Processing Unit (CPU) is where the computer system performs the manipulation of data. Every computer must have at least one CPU to function.
A processor is composed of:control unitArithmetic / logic unit (ALU)
Control unit
The control unit oversees the operation of the CPU by performing:Fetch - get an instruction from memoryDecode - decide what the instruction means and direct the necessary data be moved from memory to the ALU
The combination of Fetch and Decode is called, Instruction Time or I-Time
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Processor, Continued
Arithmetic / Logic Unit
The ALU performs two classes of operations: Arithmetic operations Logical operations
The ALU is responsible for: Execute Store
The combination of Execute and Store is call Execution-Time, or E-Time
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Processor, Continued
Arithmetic operations
The arithmetic operations performed by the ALU are:AdditionSubtractionMultiplicationDivision
Older ALUs could only perform addition and subtraction. The multiplication and division operations were performed through a set of instructions.
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Processor, Continued
Logic operations
The logic operations, or tests, performed by the ALU are:Equal-toGreater thanLess than
These can be combined to create an additional three tests:Greater than or equalLess than or equalGreater than or Less than (not equal)
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Processor, Continued
Machine cycle
A machine cycle is the combination of I-Time and E-Time.
The I-Time and E-Time differs from instruction to instruction, therefore the machine cycle will also be different.
Diagram of a machine cycle
This a diagram of the steps in a machine cycle:
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Processor, Continued
Processor speed
The speed of a processor is based on different factors:Clock speedNumber of instructionsInternal cache
Clock speed
The operations that are taking place in a CPU need to be organized to prevent chaos. For example, an addition operation cannot be executed until the data has finished being read from RAM.
To control the timing within the CPU, a clock is used to synchronize the operations. The clock simply supplies a stream of pulses at a very fast fixed rate.
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Processor: Clock speed, Continued
Clock speed, continued
The speed of the processor might be measure based on: the speed of the clock:
Megahertz - millions of cycles per second, abbreviated MHz Gigahertz - billions of cycles per second, abbreviated GHz
the number of machine cycles per second MIPS - million instructions per second BIPS - billion instructions per second
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Processor, Continued
Number of instructions
Within a conventional processor there are many instructions that are rarely used. By eliminating the rarely instructions, processor speed can be increased.
Processors are now also classed based on their instruction set:CISC - Complex Instruction Set ComputerRISC - Reduced Instruction Set Computer
RISC processors can outperform CISC processors by a factor of 4 to 10.
Internal cache
Internal cache is a small block of very fast memory manufactured into the processor. It behaves the same way as external cache memory
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Processor, Continued
Operating modes of the Intel processor
An Intel processor has several operating modes:Protected modeReal modeVirtual mode
Protected mode
This is the native operating mode of the processor, and provides facilities for multitasking.
Real mode
The processor emulates an 8086 or 8088 processor, but at a higher speed.
Virtual mode
Emulates 8086 / 8088 processor in a protected, multitasking environment.
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Processor, Continued
The Intel evolution
The following history and commentary is taken from Intel's web site:
http://www.intel.com/intel/museum/25anniv/hof/hof_main.htm11
1978 - 8086 / 8088 Microprocessor
A pivotal sale to IBM's new personal computer division made the 8088 the brains of IBM's new hit product--the IBM PC. The 8088's success propelled Intel into the ranks of the Fortune 500, and Fortune magazine named the company one of the "Business Triumphs of the Seventies."
1982 - 80286 Microprocessor
The 286, also known as the 80286, was the first Intel processor that could run all the software written for its predecessor. This software compatibility remains a hallmark of Intel's family of microprocessors. Within 6 years of it release, there were an estimated 15 million 286-based personal computers installed around the world.
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Processor, Continued
The Intel evolution, continued
1985 - Intel386
The Intel386(TM) microprocessor featured 275,000 transistors--more than 100 times as many as the original 4004. It was a 32-bit chip and was "multi-tasking," meaning it could run multiple programs at the same time.
1989 - Intel486
The 486(TM) processor generation really meant you go from a command-level computer into point-and-click computing. "I could have a color computer for the first time and do desktop publishing at a significant speed," recalls technology historian David K. Allison of the Smithsonian's National Museum of American History. The Intel 486(TM) processor was the first to offer a built-in math coprocessor, which speeds up computing because it offloads complex math functions from the central processor.
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Processor, Continued
The Intel evolution, continued
1993 - PentiumThe Pentium® processor allowed computers to more easily incorporate "real world" data such as speech, sound, handwriting and photographic images. The Pentium brand, mentioned in the comics and on television talk shows, became a household word soon after introduction.
These are pictures of a Pentium microprocessor:
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Processor, Continued
The Intel evolution, continued
1997 - Pentium IIThe 7.5 million-transistor Pentium® II processor incorporates Intel MMXTM technology, which is designed specifically to process video, audio and graphics data efficiently. It was introduced in innovative Single Edge Contact (S.E.C) Cartridge that also incorporated a high-speed cache memory chip. With this chip, PC users can capture, edit and share digital photos with friends and family via the Internet; edit and add text, music or between-scene transitions to home movies; and, with a video phone, send video over standard phone lines and the Internet.
1999 - Pentium III
The Pentium® III processor features 70 new instructions--Internet Streaming SIMD extensions-- that dramatically enhance the performance of advanced imaging, 3-D, streaming audio, video and speech recognition applications. It was designed to significantly enhance Internet experiences, allowing users to do such things as browse through realistic online museums and stores and download high-quality video. The processor incorporates 9.5 million transistors, and was introduced using 0.25-micron technology.
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Processor, Continued
The Intel evolution, continued
2001 - Pentium 4
The Intel® Pentium® 4 processor, Intel's most advanced, most powerful processor, is based on the new Intel® NetBurst[tm] micro-architecture. The Pentium 4 processor is designed to deliver performance across applications and usages where end users can truly appreciate and experience the performance. These applications include Internet audio and streaming video, image processing, video content creation, speech, 3D, CAD, games, multi-media, and multi-tasking user environments. The Intel Pentium 4 processor delivers this world-class performance for consumer enthusiast and business professional desktop users as well as for entry level workstation users
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Secondary Storage
Purpose
The purpose of secondary storage is to: retain data and programs while the computer system is turned off hold data and programs that cannot fit into primary storage
Types of secondary storage
Secondary storage is composed of two main groups of media, within each group are many types of secondary storage. The most common are:
Magnetic media floppy diskette hard disk
Optical media CD-ROM
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Secondary Storage, Continued
Measuring storage capacity
Secondary storage devices use the same units of measurement as primary storage.
How magnetic media works
Although there are other magnetic media-based secondary storage devices, the most common are disks. This is a description of how a disk works.
The data is stored on the disk as magnetized spots, and is read or written using a 'read/write head'.
To read the data, the spots are converted into electrical impulses to represent the data.To write data, electrical pulses are converted into magnetized spots on the disk to represent the data.
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Secondary Storage, Continued
Disk layout
Disks are flat, round platters housed in a case that protects their surface from contamination.
Tracks
The logical structure of disk consists of a series of concentric rings, called tracks.
Sectors
These tracks are subdivided into sectors. The Sectors contain the data.
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Secondary Storage, Continued
Sectors, continued
This is a diagrammatic representation of tracks and sectors:
Note that the outer sectors are bigger than the inner sectors. The track layout is optimized by assigning more sectors to outer tracks than inner tracks. This is called Zone Recording.
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Secondary Storage, Continued
Clusters
Depending on the operating system of the computer that is managing the disk, sectors may be placed into 'Clusters' of sectors (2 to 8 sectors per cluster). The operating system treats the cluster as a unit of storage.
Cylinders
When a hard disk has multiple platters stacked one over another, the tracks that are directly above or below each other are considered part of the same cylinder.
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Secondary Storage, Continued
Contamination of disk surfaces
The read/write head that is responsible for placing the magnetized spots on the disk, is very close to the surface of the disk. Any slight contamination will cause disk failures, sometimes referred to as head crashes.
This is a diagram showing relative sizes of contaminants on a disk surface:
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Secondary Storage, Continued
Floppy diskette
A floppy diskette derives its name from the nature of the platter that data is stored on; it is flexible Mylar
Typical capacity
The typical floppy diskette can hold 1.44MB
Diagram
This is a diagram of the parts of a floppy diskette:
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Secondary Storage, Continued
Hard disk
A hard disk derives its name from the nature of the platter that data is stored on; it is non-flexible metal platter.
Typical capacity
Capacity ranges based on how much you are willing to spend. 40GB to 250 GB hard disks are not uncommon.
Diagram
This is a diagram of a hard disk that has had its cover removed.
Caution: do not do this with a functional hard disk.73
Secondary Storage, Continued
How optical media works
Unlike magnetic media, the write technology is different than the read technology for optical media.
When writing optical media, laser heat produces tiny spots on the metallic surface of the disk.
When reading optical media, a laser reflected off the surface picks up the spots.
Disk layout
The layout of optical disks is the same as for magnetic disks.
CD-ROM
CD-ROM derives its name from 'Compact Disk- Read Only Memory'. The significance of 'ROM' in its name means that once written (usually during manufacture), the contents of the disk cannot be altered.
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Secondary Storage, Continued
Typical capacity
The contemporary CD-ROM can store up to 700MB.
Access speed terms
There are common terms used when defining the speed of operation of a disk:
Seek Time: The time it takes the Read/Write head to be positioned over a track
Rotational Delay: The time it takes for a sector to rotate under the read/write head
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Computer Systems
Input / output
Although there are elements of computer systems that can be easily categorized as either input or output, there are other devices that can be used for either:
Serial port Parallel port USB port SCSI port
Serial port
A serial port is used to send/receive data one bit at a time. Typical speed: 14.4KB/second Maximum number of devices concurrently attached: 1
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Input / Output, Continued
Parallel port
A parallel port was originally for output only. Typical speed: 50KB/second - 150KB/second Maximum number of devices concurrently attached: 1
New versions allow for input and output of data.
USB port
USB is an acronym for Universal Serial Bus. This is a relatively new technology. The intent is to be able to attach devices without having special interface cards for each device.
Typical speed: 1.5MB/second Maximum number of devices concurrently attached: 127
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Input / Output, Continued
SCSI port
SCSI is an acronym for Small Computer System Interface. This was the original high speed interface for computers.
Typical speed: 320MB/second (new technology) Maximum number of devices concurrently attached: 16 (new technology)
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Your PC - Turned Off
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
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Power Supply
Press the Power Button
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
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Power Supply
Signal the CPU to Start
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
CPU Gets Initial Instructions
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
Self Test
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
Check for Boot Sector
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
Check for Boot Sector - Found it
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
Boot Sector Leads to Loading of O/S
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
O/S Loaded - PC Operational
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
Additional O/S & Programs Loaded as Req'd
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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Power Supply
Cast of Characters
Power Supply CPU
BIOS
Hard Disk
Floppy Disk
RAM
CPU
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