Chapter III

Understanding computer hardware

1- Introduction about computer evolution a. Human being started the chase for computation help since the dawn of

civilization. We witness the chase continue presently at a faster pace and sure its trend is to persist in the future at much faster pace because of the progressive emerging needs for digital information processing in the human society and the global environment.

b. The earliest known computing tool is the Abacus (figur3-1 and 3-2), also called “counting frame” that consists of beads sliding on metal wires fit into a rectangular wood or bamboo frame.Figure 3-1: Abacus sample (courtesy MS clip art gallery)

Figure 3-2: Abacus sample (courtesy MS clip art gallery)

i. The abacus was used since 3000 BC (long before human knew the numeral systems) by the Sumerian, the Egyptians, the Phoenicians, the Persians, the Greeks and the Romans and most ancient civilizations and it is still used by merchants and clerks in some countries in Asia, Africa, the Middle East.

ii. In 1985 Robert Good Jr. explained in his article published in the “Journal of computers” an approach in Mathematics and science teaching using a binary

Abacus. Normal Abaci were used in schools around the world to teach numeral systems and mathematical operations.

iii. In the early 1980s Tim Cranmer developed an abacus (known now as Cranmer abacus) for the blind and vision impaired people after having developed the modern braille code.

c. In 1645, Blaise Pascal, famous French mathematician and philosopher, invented a machine he called Pascaline which is a mechanical calculator, but that machine was subject to a lot of problems.

d. Digital electronic computers:i. The first digital electronic computer was introduced in 1937 by J. Atanasoff and

C. Berry Known as ABC (Atanasoff-Berry-Computer).ii. In 1943, Dr. J Mauchly and J Eckert Jr. and their team completed their 30 metric

tons ENIAC (Electronic Numerical Integrator and Computer) with big dimensions 30x50 feet. That computer with its 18000 vacuum tubes needed more than 150 kilowatts of power.

2- Digital electronic device/computer: a. Modern industry uses a lot of digital electronic devices to perform automatic functions

in many products such as:i. Automobile industry uses a computer like device to control many of the car

performances.ii. Appliances: cooler, Freezer, washer/dryer, dishwasher, etc…

iii. Construction business use electronic devices in many building activities.iv. Hospital machineryv. Smart weapon and military industry

vi. GPS and autopilot devices vii. Most modern devices and equipment used in all human and life activity enjoy

the enhanced high performance digital electronic devices.b. A modern computer is a digital electronic device used by people to help them make

correct decisions and efficiently tackle the heavy load of daily data and information generated by:

i. Their social life and living environmentii. Their business environment

iii. Their education and literacyiv. Their entertainment and knowledge needsv. The natural global variables.

3- Computer components: a. Computer industry evolve around three computer components

i. Computer Hardwareii. Computer software

iii. Computer malware

b. Computer hardware comprises structural computer components and peripherals that also comprise all type of devices that complement the computer system and enhance its operational performance.

c. The ultimate goal set for a computer in the early steps was to have a device that can compute numbers and help in solving mathematical problems.

d. After the adaptation of the binary numeration system and the implementation of the binary digital data representation, the computer goals were set much higher as it became possible to simulate human functions enhanced with super speed, super precision and super power.

e. To be able to simulate human activity a computer must be able to:i. Accept all types of data input

ii. Process data into informationiii. Produce all needed types of outputiv. Provide high flexibility and perfect accuracy. v. Store information and be ready to retrieve it and use it when needed.

vi. Communicate easily with users and other computers.f. To fit these obligations computer hardware components are composed of the following

hardware devices: (Figure 3-3)i. Input devices:

1. Mouse and pointing devices2. Touch screen and stylus input3. Text input: keyboard, scanners, text recognition4. Multimedia input: Microphone, digital camera and video camera.5. Sensors with diverse input roles.

ii. Processing devices1. Processor also called microprocessor.2. Advanced technology to enhance its processing speed

iii. Storage devices: 1. Magnetic storage2. Optical storage 3. Solid state storage

iv. Output devices1. Monitor 2. Printers 3. Laser4. Audio5. video6. Various automated tools in various business activities

v. Communication devices1. Network interface card2. Network Modem3. Internet modem

4. Various slot to connect various devicesvi. Housing and local communication and synchronization devices

1. The motherboard2. The bus3. The local wiring4. The ports5. The slots

Input

1- Input is designed to enter instructions and/or data necessary for the computer system to perform. It is used as interface with the computer.

2- Input affects all operations a computer needs to perform safely and accurately so it can provide the necessary information requested by businesses and individuals.

CMOS

Date/time

ROM

BIOSOther computer

Other computer

Figure 3-3: Computer components

Input

keyboard

Output

Monitor

Storage

Hard disk

Processor

CU ALU

Memory

RAM

3- To highlight the importance and sensitivity of input, computer people use the slogan: Garbage in Garbage out (GIGO) that necessitates rigorous verification of input safety and accuracy.

4- It is very important that business employees, as users of the business computer information system, be knowledgeable of input environment so they can determine what input technology and accessories they need:

a. To feed their computer systems with data.b. To accommodate their executives, shareholders or partners, customers and suppliersc. To provide necessary tools for all outside agents and businesses providing work or help

to their company.Input technology

Diverse hardware technologies contribute in covering the huge array of input needs. These technologies can be classified as:

1- Keyboard: The oldest known data entry typewriter style device: a. The classical keyboard consists of a set of 104 buttons or keys fit in a rectangular frame.

i. A key may represent The ASCII binary codes of two or more characters and symbols in many languages.

ii. A function or a functional operatoriii. A number or mathematical operator.

b. The most popular English keyboard is the QWERTY key board that is called by this name because the arrangement of the 1st six letters from left to right form the word QWERTY.

c. The second is DVORAKd. The newest technology is the Colemak keyboard that places the most frequently used

letters on a home row corresponding to the strongest fingers in keyboarding. Compared to the previous technologies Colemak enjoys the following strengths:

i. Faster typing ratioii. Multilingual: It accommodates more than 40 different languages

iii. Easy transition from QWERTY and DVORAKiv. Ergonomic: designed to have fewer finger jumping from one row to anotherv. Available for Android, iPhone, iPad, Google play, etc…

Figure 3-4: Colemak keyboard layout (courtesy Colemak.com)

e. AZERTY is a 104 keys keyboard used in France and other non-English speaking European countries where the A and Z swipe places with Q and W and the place of all other characters remain unchanged.

Figure 3-5: AZERTY keyboard layout (courtesy Wikipedia)

f. Chorded keyboard layout sample: Figure 3-6 (courtesy Kudzu world)

Consists of few keys and the data entry is like you play on piano chords (enter characters by pressing several keys together)

i. Each key represents a bitii. 8 keys are enough to enter 256 different combinations

iii. Chording few keys that fit in a small device would be enough to operate devices Like in smart phones, iPhone, iPad and Android

iv. Requires more practice and advanced skills.g. Optical keyboard technology:

i. Uses photo sensors and light emitting parts.ii. Sensors and light parts are mounted on printed circuit boards (PCBs)

iii. The pressed key blocks the light and activates the code of the character.2- Pointing technology : consists of 2 categories:

a. Motion detection: i. A clickable mouse slid over a smooth surface moves a pointer or cursor and

position it over a clickable target. ii. Rotating a trackball into a socket activates sensors fixed in the socket and

movestouch the cursor on the screen. Commonly used in CAD stations.iii. Joystick: used in games apply pressure while moving a stick.

Figure 3-7 Motion detection mouse (courtesy Microsoft clip art gallery)b. Touch detection :

i. Touchpad: uses electrodes layers to detect finger contact and motion so you can scroll by moving your finger while touching the pad and click by tapping on any point of the pad.

ii. Graphics tablet: also called digitizing tablet is similar to the touchpad but it is activated using an electronic or magnetic head stylus to activate the cursor

1. Used in tablet laptops.2. Also used to digitize signatures and hand written things in banks, stores

and other employment and government places.iii. Touch screen technology: based on highly sensitive electronic device embedded

into the screen of a monitor.1. The finger or stylus touch results in a change of the electric current and

send to the processor the code of the affected area.2. This technology is highly used in most modern devices like smartphones,

iPad and Android, etc…3. iPad and Android allow users to get a keyboard on the screen pad and

type exactly like using a laptop or any PC or MAC.c. Gaming technology : pressured computer industry to advance forward several devices

needed to control moving objects and play the game. Like the light pen, the light gun, the steering wheel and paddle for automobile simulators and the yoke for aircraft simulator also to highlight:

i. Game controller (remote control) and gamepadii. Wii remote controller is motion detection remote created by Nintendo for its

video games. Wii use Bluetooth to connect with game devices.3- Multimedia input technology : digitize pictures audio and video and provide it to the processor.

a. Picture (image): i. Digital camera captures live pictures, digitize them and store them on a flash

card memory to be entered to the computer later.ii. Scanner converts printed pictures and documents into bitmap files we can

consider many types of scanners that use different technology of image sensors to reproduce the image of the document.

1. Flatbed scanner: figure 3-8 takes printed documents and images that are placed on its bed and digitizes all their pixels.

Figure 3-8 (flatbed scanner(courtesy Microsoft)

2. WAND scanner: called after the ancient Pharaohs magic stick. Wand scanner scans by moving over the surface of the document.Figure 3-9: wand scanner

3. 3D scanners: used in engineering projects for industrial design.4. Drum scanners use photomultipliers tube as image sensor5. DNA scanners use charge coupled device (CCD) or photomultipliers to

detect microscopic DNA arrays.Figure 3-10: DNA micro-array scanner (curtsey U-strasbg- Fr)

b. Video: i. Digital camcorder captures and digitizes film and clip footage so they can be

processed and used by computer systems.ii. Webcam linked to the computer shoots and converts live clip footage instantly

and feed them into the system so they can be used in video telephony and teleconferencing and live news reporting

iii. Traffic camera is the base of many traffic applications (TIS: Traffic Intelligent System)

iv. The digital camera embedded in the smart phone is very convenient to shoot and email digital pictures and video clips while they are happening contributing to the greatness of this convergence device.

c. Audio : i. Microphone captures voice, sound and music and transfers them to an audio

device where they are digitized and used in the context of their happening.ii. MIDI (Musical Instrument Digital Interface) captures notes and encodes them as

digital messages into the computer processor and synchronizes the rhythm of multiple devices.

iii. MIDI piano-like keyboard doesn’t produce sounds. This keyboard send information to the computer who reproduces an array of voices or samples

iv. The MIDI protocol controls all components and parameters of the sounds of an instrument sample.

v. Perhaps the most important role of MIDI protocol is to ensure that many music devices communicate with each other and with the computer system.

d. Bare voice input recognition i. Computer can be taught to recognize spoken words.

ii. Words must correspond to vocabulary of its dictionary iii. Software application helps complete the performance.

4- Medical input technology : Of course there are too many other areas where input has specific importance. Here we will consider the health concerns.

a. MRI (Magnetic resonance imaging) use huge magnet surrounding a bed where the body is subject to resonance produced by short electromagnetic field. The resonance causes protons in the body water to align and then to rest. The measurement of these protons gives clear panorama of the inspected region and precisely shows abnormal aspects.

b. Computed tomography (CT) inputs many sectional X-rays for any penetrating wave processed by the computer to create high precision tomograms for the inspected body.

Figure 3-11: MRI scanner (courtesy mritechniciansite)

i. CT scanning is a very popular technology because of the high quality of its 3D pictures

ii. High number of tomograms produces ultra-high volume files that may be in the order of several gigabytes of data for a CT scan session.

iii. Best known technology for the diagnosis of MS (Multiple Sclerosis) illness. In the brain cells.

c. Industrial CT scanning use sectional X-rays as input used by the computer to create three-dimensional designs for products and components.

d. Ultrasonography: use frequencies that are not audible as input (2 to 18 MHz) the computer processes the waves and their influence on the body and produces scans that are easily interpreted by specialists and handily viewed by people. An example is the pregnancy sonogram.

e. Tiny digital camera introduced into human or animal veins and organs input pictures processed by computers to locate obstructions or tumors or lesions etc…

5- Network and Internet input a. Using indirect input forms designed to collect needed data for processingb. Using several direct input technologies made available by several internet services:

Example the virtual keyboards and the scripts.6- Internal input:

a. Information from files and folders on the hard disk.b. Information from files saved on several storage media.

7- Paper input technology: use perforation or marks like the barcode tag attached to all merchandise items available in stores.

8- Input technologies that feed computer system with data to produce information highlights the importance of business employees to be literate, knowledgeable and vigilant so they can contribute in designing the needed tools for their company.

Processing

Computer processing comprises steps performed by the processor to get information out of data input and program instructions and deliver it by means of output.

Figure 3-12: CT scan (courtesy UCLA-endocrinesurgery)

Processing components are all located in the computer motherboard which represents the main circuit board of the computer and provides housing for:

- All computer components.- The complementary electronic elements- The wiring that provides the internal link between them and the external link with the outside- The slots and expansion slots to fit different components- The ports that serve as interfaces with other computers and devices.

Computer processor

Central processing unit (CPU)

The computer processor or central processing unit is a thumb-nail size chip or integrated circuit that comprises 100 million to few billions of transistors and wiring that link them with the outside. It is considered as the brain of the computer.

To fulfill its mission the processor has the necessary components as follows: (figure 3-3)

1- The control unit CU that performs the readiness, supervision and control roles2- The arithmetic and logic unit ALU completes the necessary computing under the supervision of

the control unit.

Figure 3-14: computer processor chip courtesy Microsoft art Gallery

Figure 3-13 Motherboard courtesy Microsoft art Gallery

3- The computer clock: a. Processing speed is the most important characteristic of the processor. It is determined

by the processor clock and defined as the number of machine cycle instructions a processor can perform in one second.

b. In electronics, the number of cycles per second is defined as the frequency of the signal. That’s why the processor speed (as the number of cycles per second) is like the signal frequency measured in Hertz, kilohertz, megahertz, gigahertz and so forth.

c. The clock of the computer can be compared to the heart in the human body. i. The heart synchronizes the blood circulation cycle in the body.

ii. During each pulse of the heart a blood circulation cycle is completed.iii. Similarly, during each tick of the computer clock, at least one machine cycle

should be completed.iv. For example: One GHz processor can process up to one billion machine cycles

per second.v. We will go over many technologies that enable the processor to complete

several machine cycles during each clock tick!d. Machine cycle comprises 4 steps that are, in the order: Fetch, decode, execute and

store which in turn can be divided into two operational steps: i. The instruction operational step: Fetch and decode.

ii. The execution operational step: Execute and store.4- The word size (also: word width or word length) refers to the processing and addressing unit (it

is the number of bytes (or bits) that are processed by the instruction set as one unit). 5- Modern computers have word size of 32 bits (4 bytes) or 64 bits (8 bytes). While some modern

electronic devices have word size of 8, 9, 16, 24, etc…6- The word size affects the software used in the computer.

Processor speed technology

Because of the importance of processing speed computer industry is always trying to enhance speed of computer processing using many technologies that will be explained below:

Figure 3-15

Computer clock as the human heart.(courtesy Microsoft gallery

1- Pipelining technology: a. Normal processing without pipelining requires the processor to finish processing a cycle

completely before starting another cycle.Figure 3-16: regular processing of cycles

b. With pipelining the processor will be capable to process several machine cycles simultaneously.Figure 3-17: Pipelining processing of cycles

2- Co-processing technology: a. This technology assigns some sophisticated time consuming processing to specific

processors that help the main processor to tackle these specific tasks.

Figure 3-17: Floating point addition (consists of representing the added numbers with same exponent before proceeding with the addition).

b. Floating point mathematics processor achieves lengthy floating point calculations that are very frequent in scientific and complex algorithms.

c. GPU (graphics processing unit) is a co-processor that, working together with the main processor, accelerates the processing of multimedia and scientific applications. Example: NVIDIA graphics processor.

Instruction1 Instruction2 Instruction3

Fetch – Decode – execute – store – fetch – decode – execute – store – fetch …

Instruction1: Fetch – decode – execute – store

Instruction2: Fetch – decode – execute – store

Instruction3: fetch – decode – execute – store

54321.1234 + 555.444 = (5.43211234 × 10^4) + (0.05554440 × 10^4) = (5.43211234 + 0.0555444) × 10^4 = 5.487665674 × 10^4

= 54876.65674

3- Parallel processing technology :

a. Parallel processing consists of using a set of processor chips connected together in parallel and designed to team up in tackling processing tasks.

b. Software is needed to divide the processing assignments equally between the processors at the input and reconstruct the results at the output.

c. Supercomputers in general use this technology to reach ultra-high processing speed they are built to achieve.

4- Multi-core technology :a. While parallel processing technology use only one processor on each chip, multi-core

technology consists of putting two or more processors on one chip where they form one integrated circuit and they time share its electronic components.

b. Intel launched the first core-2 duo in 2006 and the quad-core i7 in 2008 with 4 processors on the same chip i7.

c. In 2010 SUN/ORACLE launched the SPARC T3 processor that has 16 processors on one chip that is a thumbnail size.

d. In 2012 AMD launched an 8-core with eight processors on the same chip.5- Supercomputers use a combined technology of thousands of multicore processors grouped in

parallel to form an ultra-powerful ultra-fast processor6- Initial speed factors- Processor clock :

a. Whether its technology is single core or multicore or parallel or combined, the speed or power of any processor is determined by the frequency of its clock which is measured in hertz (cycle per second).

b. 1 KHz= 1000 Hz, 1 MHz = 1000 KHz, 1 GHz= 1000 MHz, etc…c. Processor clock of most laptop on the market is between 2 and 3 GHz which means that

the clock ticks 2 to 3 billion ticks per second and therefore they process as much instructions.

Output

Computer output is information or action people and businesses want to get out of a computer as a result of processing input data and information.

Inpu

t soft

war

e

Processor 1

Processor 2

Processor 3

Software for results

Figure 3-18

3 processors linked in parallel

An output device is a computer component or device linked to a computer that is capable to:

1- Convey processed information to the user.2- Complete an action required by the user.

Employees of each department of a company should be able to define their output needs and coordinate with IT people to have these needs satisfied to the best possible.

Output needs may be classified as follow:

Printed output

1- Business requests for printed (hard copy) documents need different categories of printers to fulfill them and they may be divided into 3 categories:

a. Normal print-out documents: reports, letters, notes, etc… An example is when the customer service department asks for letters to be sent to clients or suppliers or agencies.

b. Special documents: paychecks, cards, etc…c. Pictures, brochure, fliers, banners and other colored forms and booklets.

2- A printer is a peripheral device that produces permanent readable hard copy designed to satisfy the needs outlined above.

3- Modern printing technology produces four types of printers:a. The dot-matrix printer: this technology uses solenoids (tiny magnets), a ribbon and a

guide plate.i. Also called impact printer because it prints by impact of the print head or

pin driven forward by a tiny magnet.ii. Prints one line at a time.

iii. Log life machine. They were very slowly.b. The inkjet printer: The most commonly used printer technology that is based on

propelling ink particles onto the paper. Two ink technologies are used:i. Continuous: uses high pressure pump and a microscopic nozzle that creates

a continuous stream of ink particles. ii. Drop on demand: Canon, Hewlett- Packard and Lexmark use thermal inkjet

process also called bubble jet (Canon trade name)iii. Another DOD technology used in Epson and Brother industries uses

software to create and direct ink bubbles in cartridge chambers.c. The laser jet printer: This technology uses laser beam, dry ink (toner) and a rotating

drum coated with selenium. It works as follow:i. The laser beam projects the image of the page on the drum

ii. Selenium photoconductors allow the charge to leak and particles of the toner to be spread depending on the light density.

iii. The heated drum prints the image (documents and photos) by direct contact that fuses the toner to the paper.

iv. Much faster and better quality than inkjet and dot-matrix printers d. The LED printer (invented by Casio): similar to the laser printer but instead of the

laser beam the LED technology uses light-emitting diodes in the print-heads. Compared to the laser printer the LED printer is:

i. More reliable and more efficient because they have less moving parts and less mechanical wear,

ii. Faster iii. Less expensive

4- Audio output: Beyond using speakers, headphones and ear buds to hear regular audio, what’s interesting about computer audio may be included in the following properties:

a. You have an endless source of music stored on your computer or available and easy to download in many online sites as Rhapsody for example.

b. You can play and hear the music in all the rooms of your house or your office and you can even access them from all the rooms.

c. You can create playlists that suit occasions and events and easily chose and change what you want to hear.

d. You can improve the quality of your audio by connecting your computer to a good audio system.

5- Video output : video components work together to show the processed frame rate of images on the monitor of computers or televisions. 2 scanning technologies and four display technologies are used:

a. Scanning technologiesi. Interlacing technology: is the older technology and consists of sending the

signal in 2 steps or intervals: One half of the image vertical or horizontal lines are sent first then the remaining half is sent later. This technology is used in most SD televisions and monitors, however it is not used in LCD (liquid crystal display) technology, gas plasma technology, or DLP ( ) technology.

ii. Progressive technology: The entire frame signals are sent simultaneously. This scanning technology is most used by high definition television and game monitors because of the easier way to compress and decompress video.

b. Display technologies i. CRT (Cathode Ray Tube) technology: based on the old vacuum tube

technology and 3 back guns that send red, green and blue electrons to activate the color on a phosphoric screen. Because of the weight and volume required to accommodate the monitor and the excessive power

consumption and generated heat, this technology was superseded by other

modern technologies.ii. LCD (liquid crystal display): This technology uses a natural liquid that have

the properties of any available liquid but its particles or molecules can be oriented and polarized like those of crystal. Liquid crystal can be found in

proteins and living cells.1. Pros:

a. Low power needs.b. Can be tailored to any size: small or largec. Excellent quality resolutiond. Very compact and light weight.

2. Cons:a. Highly influenced by temperature and lightb. Viewing angle is very limitedc. Dead pixels resulting of extensive use lower the image

quality.d. Very heavy and big volume: Prohibitive in lrge and wide

displays.iii. Gas plasma display : This technology uses a layer of ionized gas particles

similar to that of florescent lamps (vacuum bulbs) as a flat panel comprised between two layers of glass.

1. Pros: a. Excellent color due to very high contrast ratio: (10,000 : 1)b. Very fast activation responsec. Good viewing angled. Highly scalable (up to 150”: world largest screen)e.

2. Cons: a. Large size screen (42 inches and over) required for good

quality because of the large pixel pitch needed.

Figure 3-19: CRT (cathode ray tube) Monitor courtesy Microsoft

Figure 3:20 LCD (Liquid Crystal Display) courtesy Microsoft Gallery

b. Glass screen used in this technology may results often in glare and reflections.

c. Heavier than LCD because of the glass weight.d. Extended use produce deteriorated pixels that lower the

quality of gas plasma display earlier than that of LCD and LED and even CRT.

e. Consume more power than LCDiv. LED (Light Emitting Diodes) display : This technology is based on a cluster of

red green and blue diodes working together to produce the right color of each pixel. When the emissive layer used in the diode is a film of organic compound LED becomes OLED (Organic Light-Emitting Diode)..

1. Pros :a. Lighter weight than all other displaysb. Very short image response timec. Excellent color because no back light is used.d. Wide viewing anglee. Excellent contrast (more than 1000,000 to 1)f. Because of its light weight, high quality and adaptability to

any display size this display technology is used in small displays and advertisement and traffic displays

2. Cons: a. Blue deteriorate faster than other color causing bad image

quality with extensive useb. The organic material can be damaged from water and

vapor.c. Long time exposure to sun light damages the quality of the

display.d. Cost of production is higher than other displays

c. Display resolution :i. All types of display are designed so that the display is divided into cells

called pixels.ii. There are hundreds of columns and hundreds of rows that intersect in cells

forming a grid superposed on the display.iii. Each cell or pixel has its own coordinates and its own RGB (red, green and

blue) color components.iv. Resolution = columns x rows = Number of pixelsv. The higher the resolution the better the quality of the image and the lower

the resolution the lower the quality is.vi. The resolution doesn’t change with the size of the screen because it is

always a fixed product of the columns and the cells.

vii. Higher resolution requires higher image file volume and faster Internet access to upload and download it.

6- Spoken words output a. Computer can also speak words in all languages if we teach it to speak.b. Spoken words are chosen from a word dictionary and articulated as per a grammar

algorithm.c. A software help complete this job.

Storage

Computer storage components provide a way for the computer to store and retrieve data and information needed for its computation operations and allow business people who use the computer to have needed information available when they need it for their applications.

Storage fall under two categories: Temporary and permanent.

1- Temporary or volatile storage: Needed to store data and application programs during the processing. It is blank when the power is off. The following components are volatile or temporary storage components:

a. Registers: Briefly used by the processor to store the numbers to compute and the result of the computation.

b. RAM (Random Access Memory): It is a memory chip (typically referred to as DRAM, Dynamic RAM) that can store hundreds of billions of bytes (100 Gigabytes) and more in most modern computers. It is used as the waiting lobby for all elements used by the processor to process an application. (Figure 3-3)

c. DRAM solid state storage technology uses semi-conductors; it is a volatile or temporary memory because its semi-conductors need power to keep the stored items which are lost when the power is OFF.

d. Because RAM is volatile, files must be saved before you quit the computer or turn it OFF for any reason and updates should be saved frequently so that they will not be lost accidently.

e. RAM is divided by the operating system into several compartments each assigned to a specific type of data or information during the processing, as follow:

i. The operating system compartmentii. The input compartment

iii. The output compartmentiv. The processing results compartment v. Interface compartment

vi. This memory allocation should be strictly enforced and no break-in through the borders must be allowed under any circumstances. Otherwise the system will break down immediately.

f. RAM is a must visit temporary stay area for everything that is:i. Input to the computer

ii. Output from the computeriii. Input to the processoriv. Output from the processorv. Input from all other storage media

vi. Output to all other storage media.g. Cache: is a solid state volatile fast memory chip. This chip is checked first by the

processor when it looks for instructions or data needed that is why:i. It is small (kilobytes)

ii. May be dispersed to 2 or 3 levelsiii. Used to store most recently and most frequently used instructions and data to

allow for the fastest possible processor access.2- Internal permanent storage : When the computer power is off the computer is not dead; it is

sleeping because it will restart when the power is turned ON again! And what about the date and time that stay running and up when the computer is off?

a. ROM (Read Only Memory): is a permanent solid state storage chip that holds instructions and data recorded in the factory: (Figure 3-3)

i. Hold the BIOS (Basic Input Output System) ii. When you turn the power ON the BIOS is activated and takes control of the boot

process by extracting a copy of the operating system kernel from the hard disk and place it into RAM

iii. When it is fully there the operating system take control and finish the waking-up process called the booting process.

iv. Mobile computer like the smart phones and PDAs that have no hard disk (they instead have a flash drive) don’t need any booting. They are up right when power is ON.

b. CMOS (Complementary Metal-Oxide Semiconductor ): Semi-permanent chip get its power from a tiny rechargeable battery fixed in the mother board. It holds the following information: (Figure 3-3)

i. Configuration of the computer system to help the BIOS and the operating system in the booting process.

ii. The date and time always updated shown on the right bottom corner of the monitor and supplied to all computer components and programs that need them.

c. Virtual memory (VRAM) : i. Virtual memory is not a chip nor is volatile because it is a part of the HDD

configured as an extension of the actual RAM.ii. Unlike Cache used to store most recently and frequently accessed items, VRAM

is much bigger storage used to store the least frequently accessed items.iii. Processor starts looking for needed items as follow: Cache then RAM then

VRAM then other assigned media.

3- Permanent mass storage technology : Includes the primary storage medium, which is the internal hard disk drive and all other secondary and external storage media where three different technologies are used:

a. Magnetic technology : i. This technology represents the most common and strongest removable

mass storage technologyii. Magnetized surface is populated by magnetic grains (grain size = 10

nanometer = 0.00,000,001 mm).iii. That surface pass close to read-write magnetic heads that arrange them

into ASCII code in the recording phase and read the arrangement and convert it into ASCII characters during the reading phase.

iv. The gap between the head and the surface of the medium is somewhere between 10 and 50 nanometers.

v. A particle of dust or smoke is at least 10 times bigger than the gap that is why you must:

1. Keep the computer clean and away from dust, smoke and humidity

2. Never abruptly move the computer or shake it while the hard disk is spinning.

vi. Examples of magnetic technology are:1. The hard disk drive (HDD) which was introduced by IBM in 1956

is until today the main mass storage unit of any computer. It is formed of:

a. Stack of magnetized platters (2.5” diameter in laptop computers, 3.5” in desktop computers) that spin around an axis.

b. Beam of read write heads position themselves between the moving platters.

c. SATA (Serial Advanced Technology Attachment) form the mass storage interface for data exchange with RAM.

d. Major manufacturers worldwide are: Western digital, Toshiba and Seagate.

e. HDD estimated worldwide sales may surpass 40 billion dollars in 2012.

Figure 3-21 (hard disk- magnetic storage technology courtesy Microsoft Gallery)

2. Magnetic bands used to store information on the back of most used cards like:

a. Credit cardsb. Gift cards abundantly used by stores as very popular

gifts that help in the promotion and marketing.c. Driver licenses and other ID cards.d. Hotels door opener and similar applications.

3. Magnetic tape : A sequential high endurance mass storage presently used for backing up extensive mass data because of their very low cost compared with other media.

b. Optical technology:

i. This technology uses low-power laser beams to create pits (1-3 microns long X 0.5 micron wide x 0.1 micron deep) on the mirror like surface of the disk (12 cm of diameter).

ii. The disk surface comprises a layer of polycarbonate plastic, where the pits are perforated, covered by a thin aluminum layer that reflects light where no pits are present and a layer of lacquer that protects the surface.

iii. In the reading phase the laser beam scans the surface the beam will have a sharp reflection that represents (1) (no pits = lands) and dim reflection over the pit (0).

iv. Disk capacity is function of the gap between pits of the medium surface:1. CDR and CDRW store around .7 megabyte2. DVDR and DVDRW store 7 gigabytes3. BDVD stores 25 gigabytes.

v. Optical technology pros: 1. Very high condensation in small area (superior capacity

compared with Magnetic technology).2. Excellent quality sound and graphics.3. Inexpensive 4. Recorded data is not affected by power outage and magnetic

field disturbance

Figre3-22: Optical storage technology courtesy Microsoft Gallery.

5. Disk doesn’t need to be protected into closed boxes and their scanning devices are durable because they have few moving parts subject to wear.

vi. Optical technology cons: 1. Very slow compared to other media2. Cannot be used inside the system unit3. Rewritable media must be burned and prepared to be able to

erase previous recording before recording again on the same area.

c. Solid state non-volatile storage technology:

i. This technology utilizes non-volatile semiconductors that can be rewritten electrically and does not require power to retain data.

ii. Two types are available depending on the logic gate used to get the data: NAND and NOR.

iii. The NAND (Not AND) electronic logic gate technology developed by Toshiba allows access to a page or bloc of data; it is designed to ultimately replace the magnetic HDD. It outputs (1) if both inputs are similar (both ones or both zeroes)

iv. The NOR (Not OR) electronic logic gate technology was developed by Intel allows access to a single byte in the chip. Produce (1) only if the 2 inputs are zeroes

v. Solid state pros: 1. Used by cache, ROM, Flash memory, Flash drive, smart phones

and so forth to replace HDD.2. No moving parts3. Faster and more consistent input/output4. Requires less power than other storage technologies.5. Much faster than HDD in supplying needed data to the

processor (much shorter latency)vi. Solid state cons:

1. Can wear out faster than other media.2. Read and write operations apply to one complete page.

Figure 3-23: USB drive built with solid state technology courtesy Microsoft Gallery

3. Erase operations apply to a bloc of the page (less operational flexibility compared to other storage media).

4. Prohibitive cost (2 terabyte of solid state may cost about $ 500,000 while a 2 terabytes HDD costs less than $200.

d. Future storage technologies: Holographic data storage system (SSDS) i. This technology is still under development. Although over half decade of

research and millions of dollars were spent, it was lately introduced in a LAS VEGAS convention in May 2012 (NAB).

ii. This is a WORM (Write Once Read Many) archival storage technology that consists of using two laser beams that create 3D holograms to store pages of data and retrieve them by memorizing the storage angle.

iii. Holograms are stored on top of each other so it can store 1 gigabyte on 2 cubic mm.

iv. Holograms don’t wear fast (life span is over 50 years) v. Holography disks are well protected from weather, heat, humidity and

handling.vi. SSDS media are fast and flexible (less than 10 seconds to access any

hologram data.e. Future storage technology: Molecular storage memory

i. Inspired by DNA principles, scientists aims to develop synthetic strands in molecules similar to those of the DNA.

ii. The density may be million times higher than other available storage technology.

iii. This technology is underway and will possibly be the future breakthrough in the storage industry.

iv. Reading University researchers announced their findings on this subject in early in 2010 and technology development is underway.