Chapter 1 Hardware and software
Amazon Instant Video
(about $99/year, or per-item purchases)
A CPU (central processing unit.) وحدة معالجة مركزية
(conceptually) runs a program's instructions one at a time. The speed at which a CPU runs instructions is governed by a ticking clock signal. The clock synchronizes all the CPU's components, like a drumbeat synchronizes a marching band. If a CPU's clock ticks 1 billion times per second, then the CPU may run 1 billion instructions per second
Hulu Plus
(mostly TV shows, about $8/month),
The 2013 Encyclopedia Britannica (many books)
(now available free online) had 40,000 articles, while Wikipedia has over 4,000,000. The approach has also led to articles that essentially summarize news events as they happen, serving as a complement to news stories that tend to only cover the most recent unfoldings of an event. Ex: The article on the 2011 Japanese Tsunami evolved as events unfolded, and is now a thorough summary based on over 350 news stories that are referenced at the article's end.
Device size
Device size is measured diagonally. Desktop monitors are typically between 17" to 30". Laptops and tablets have smaller screen sizes and are typically between 11" to 17".
Duplex both side printing
Duplex is a feature that enables a printer to print on both sides of the paper. Automatic duplex means the printer will automatically turn the paper over. Manual duplex requires a user to flip the paper over and re-feed the paper into the printer.
How much memory does the computer have?
GB means gigabytes. So the computer has 4 billion bytes of memory.
Moore's Law
Gordon Moore, a co-founder of Intel, made that prediction in 1965. The doubling occurs because engineers keep shrinking the size of the circuit's components: transistors and wires. EX: f cars had doubled in their people capacity every 2 years and could originally hold 1 person in 1960, a car would hold 33,554,432 people in 2010, which is 50 years or 25 doublings late has indeed happened with ICs, which is why computers continue to get faster and smaller every year. A 1960 IC could hold just a few transistors, but a modern IC can hold billions.
integrated circuit (IC for short) دارة متكاملة
IC around 1960, Computers are built from transistor circuits that appear on a fingernail-sized device/ IC is also called a chip, due to being sliced from a larger chunk of silicon, like a potato chip is sliced from a potato. IC's have doubled in circuit capacity about every 1.5 or 2 years, a trend known as Moore's Law.
computers
In the 1940's-1970's, most computers were big expensive machines. As technology enabled smaller/cheaper computers, various different types of computers have evolved. Many computer types exist today, including servers, PCs, laptops, tablets, and smartphones. Computer types continue to evolve.
machine language
Like a chef executes a recipe's instructions, a CPU executes a program's instructions. However, because a CPU only understands 0's and 1's, instructions must be just 0's and 1's, such instructions known
How much L3 cache does the computer have
MB means megabytes. Thus, 3 million bytes. Note: L3 means level 3 cache; there's actually more cache inside the processor (levels 1 and 2).
Audio streaming
Music and radio broadcasts are also frequently streamed. In 2016, streaming music hit 251.9 billion streams and accounted for 38% of all audio consumption, becoming the largest share of audio consumption. Also, 80% of the U.S. population streamed music in 2016, an increase of 76% from 2015 (
Video Sharing
One of the most powerful evolving features of the Internet is the ability to easily share videos. Previously, most videos recorded by an individual would be viewed by just a handful of friends and family. Today, an individual might create a video that becomes viewed by millions of people. Videos of newsworthy events (accidents, police brutality, protests, etc.) have had huge impacts on people's attitudes, creation of laws, and more. And videos of funny cats have entertained millions.
Cable connectors (interface) projector
Physical connectors located on the projector and laptop determine the type of cable that can be used to connect the devices. An HDMI (high-definition multimedia interface) cable transmits video and sound using a digital signal. A VGA (video graphics array) cable is an older technology that uses an analog signal to transmit video. A projector may support multiple types of cable connectors such as VGA, HDMI, AV, SD, USB, and Micro USB.
live stream
Popular live streaming platforms and applications include Facebook, Instagram, Twitch, Ustream, Livestream, and Periscope. Facebook, which has over 1.7 billion users, saw a 400% growth in live streaming between May and October 2016 (Source: Variety) and has become one of the largest live streaming platforms in the world. Some platforms allow users to share live videos with friends, specific friends, or the public. Facebook Live videos also allow for users to receive instant feedback from viewers in the form of text and reaction emojis. Since beginning the live streaming feature in 2015, Facebook has encouraged VIP users (media groups and celebrities) to use the live streaming feature by offering incentives, including money (Source: Re/code). By mid to late 2016, many news organizations, such as The New York Time and CSPAN, used Facebook Live to report late-breaking stories and provide coverage of international political events. Live streaming is also popular amongst the general public, enabling the public to be on the forefront of news stories and tell news from their perspective. Using their computers and mobile devices, users can share their moments of joy and turmoil. In 2016, Facebook Live was famously used to show a mom playing with a Chewbacca mask, the aftermath of a police shooting in the U.S., and pleas for help from residents in Aleppo, Syria.
Resolution for printer (DPI) دقة الطابعة dpi or dots per inch.
Printer resolution is measured in dpi or dots per inch. A 300 dpi printer can print 300 distinct dots within a one inch wide single line.
Lamp life مصباح
Projectors use a lamp as the light source. The lamp life is measured in hours and estimates the number of hours until the lamp becomes too dim to be useful.
Resolution
Resolution is the number of distinct pixels used to display an image. Ex: 1600 x 900 indicates that the display contains 1600 pixels on each of the 900 lines, so the display contains a total of 1,440,000 pixels. Devices with higher resolutions yield a sharper image and can display more information in the same area.
SMTP (Simple Mail Transfer Protocol)
Systems usually use a separate server for sending email is an Internet protocol for sending email. An SMTP server's name commonly starts with smtp, as in smtp.gmail.com.
Brightness
The brightness of a projector is measured in lumens. A projector used in a small classroom typically ranges from 2000 to 3000 lumens,شمعة while a high-performance projector intended for a larger space ranges from 3000 to 4500 lumens.
Netflix
The largest movie and TV show streaming company in the world is Netflix, whose traffic accounts for over 30% of all Internet traffic (Source: Time). Netflix started in 1997 as a DVD rent-by-mail company (a DVD (digital video disk) is a physical disk that can store a movie and is played using a special DVD player). With the rise of faster Internet access in homes, Netflix introduced streaming in 2007, which dominates the company's revenues of $5 billion in 2014, earned largely through a monthly subscription fee (about $9/month in 2014). Other movie/TV-show streaming services include
Resolution
The number of distinct pixels used to display an image on a monitor or screen. Ex: 1600 x 900 indicates that the display contains 1600 pixels on each of the 900 lines, so the display contains a total of 1,440,000 pixels. Devices with higher resolutions yield a sharper image and can display more information in the same area.
Projection distance (throw distance) projector
The projection distance specifies the distance between the projector and the screen. The projector distance is sometimes referred to as the throw distance because the distance specifies how far an image is "thrown". Standard projectors typically require a projection distance of 10 to 15 feet to fill an 8 foot screen. Projectors may also have minimum projection distance requirements to ensure an image is focused. A short throw projector is designed to project a large image in a small space, typically with a projection distance of just 2 to 4 feet.
Aspect ratio ابعاد متزنة
The ratio of the width to the height of an image. Ex: 4:3 means that for every 4 units of width the image is 3 units tall. The two most commonly used aspect ratios are 4:3 (fullscreen) and 16:9 (widescreen).
Speed printing (PPM) pages per minute.
The speed of a printer is measured in ppm or pages per minute. Printer speed refers to the number of pages of black text that is produced in one minute. A printer speed of 7 ppm means the printer can print 7 pages of black text per minute. Colored text or images require additional time to print, with such time depending on the image being printed.
touchscreen
The touchscreen is typically a transparent item placed on top of the display. Like a touchpad, a touchscreen use small electrical signals that are affected by human skin because skin conducts electricity (due to skin's internal moisture). a stylus can also be detected by a touchscreen, and can thus be used for writing or drawing.A finger with gloves may not be detected. A wet finger may cause multiple points to be generated.
computer speaker
a common audio output device that converts an electrical signal to music, sound, or speech. Most computers and mobile devices contain small internal speakers. External speakers can be connected if a user requires higher quality sound. Audio may disturb others in a crowded office or computer lab. A user can wear headphones or earbuds, so that only the user can hear the audio. Headphones and earbuds are connected to a computer or mobile device through the device's audio port.
hard disk drive (HDD)محرك القرص الصلب
a drive consisted of a spinning disk that stored bits using magnetism The spinning is part of the sound that a desktop or laptop computer may make; the other sound is the cooling fan.
Nupedia المقالات التي تم مراجعتها
a free online encyclopedia, is considered the predecessor to Wikipedia. Volunteers wrote articles, which were then peer-reviewed by experts to ensure only high-quality articles are published. Due to the extensive reviewing process, Nupedia published only 21 articles in the first year (SourceWikipedia). Wikipedia was introduced to enable the development of collaborative articles via a wiki, which would then be peer-reviewed by experts and published by Nupedia. Wikipedia's collaborative authoring platform quickly outpaced Nupedia, releasing 200 articles in the first month and 18,000 articles in the first year. Wikipedia was formally launched in January 2001. In 2015, Wikipedia was the 6th most popular website in the world.
a message sent via computer from a user to other users, containing mostly text but sometimes containing additional items like images or attached documents. Email predates the web and even predates the Internet, with early forms in the 1960's and 1970's. In 2015, the most popular email systems included Gmail, Yahoo, Hotmail, Outlook, and AOL. Among those, Gmail is the relative newcomer, starting in 2004, but in 2015 having the largest number of users. Gmail became popular in large part due to boasting large amounts of storage (so users would not need to delete emails to avoid using up available storage), due to excellent email search, and a good spam filter. Those email systems are mostly free to users, typically supported by advertising that appears alongside emails.
The Wikimedia Foundation free educational content.
a non-profit organization known for hosting Wikipedia. Wikimedia's mission is to support wiki-based projects to provide free educational content. Wikimedia hosts a number of additional sites including Wikibooks (textbooks), Wikimedia Commons (images, videos, sound), Wikivoyage (travel guide), Wikiversity (tutorials and courses), among others. Unlike many free websites, Wikimedia does not rely on ads for revenue and instead relies on annual fundraising campaigns. Fundraising banners are posted each year asking users for donations. In 2013/2014, the fundraising efforts raised $51 million (USD).
speech recognition
app converts audio into text by recognizing spoken words. Modern speech recognizers go beyond just converting sounds to words, but rather strive to understand the context of the words so as to yield "How's the weather today" rather than "How's the whether today", A GPS device may do speech recognition locally. Siri--> a server--> run more powerful speech recognition
quad-core رباعية النوى
chip has four CPUs on the chip. 8-core and 16-core chips appeared around 2015, initially used mostly in servers, then making their way into desktop and laptop computers.
dual-core ثنائي النواة
chip has two CPUs on the chip, each CPU known as a core, having appeared first around 2005
solid-state drive (SSD)أقراص الحالة الصلبة.
commonly implements a drive, using a computer chip (with no moving parts) instead of a spinning disk to store data. SSD is short for solid-state drive. SSD's are faster but more expensive than disks.
laser printer
contains a rotating ink drum that is electrostatically charged by a laser. The charged areas form a pattern that picks up powdered ink, or toner, and places the ink on paper. The paper next passes through a fuser unit that uses heat and pressure to permanently bond the ink to the paper. As the ink drum rotates, the entire surface is exposed to a discharge lamp, which wipes the previous pattern so that a new pattern can be added Color laser printers may make multiple passes to apply different colors or contain multiple ink drums for each colorlaser printer
The instruction ancestors = 2
creates a variable (a variable is a named memory location) called ancestors, initially storing 2. The text on a line after a # is a comment, which is just a note, ignored by the program.
optical mouse الفأرة البصرية
detects movement using an optical sensor, which is a very basic camera; informally stated, the mouse takes quick photos (very simple ones) of the surface below, and by comparing features in successive photos, calculates the direction and distance the mouse was moved. (a granite countertop with intricate patterns, or a glass table) may result in a mouse pointer that jumps around; a mouse pad (or paper, book cover, etc.) can be placed under the mouse in that case.
LCD (liquid crystal display)
early 2000s monitor consists of liquid crystals sandwiched between polarizing filters. The crystals are normally twisted in a helix pattern. Applying voltage causes the crystals to untwist, which rotates the polarizing filters and controls the amount of light that is passed from a backlight to the front of the monitor.Light does not pass through if the polarizing filters are rotated at a 90 degree angle from one another, which results in a black color. Color is achieved by passing the light through red, green, and blue filters that combine to form a single pixel. Hundreds of thousands of pixels are independently controlled to create the resulting image. LCD monitors are smaller and consume less power than CRT monitors. The same LCD technology used in computer monitors is also used in televisions, smartphones, watches, car displays, and more.
myspace
early large social networking sites was started in 2003, with an emphasis on music. In 2006, myspace.com was the most visited website in the U.S. (Source: Mashable). Both sites have only modest popularity today.
Many computer systems
have a drive, memory, and cache. Thus, a part of needed instructions/data is first copied to memory, and then an even smaller part is copied to cache. So, larger memory and/or cache can yield faster-running programs due to less-frequent copying. A PC/laptop owner can usually increase computer speed by adding memory (either adding more memory chips, or replacing existing memory chips with larger ones), but usually cannot add cache because cache is built into the CPU chip.
smart TVs
have evolved that can connect to a home's WiFi network and thus directly stream movies.
A computer's memory (RAM)
holds data temporarily; when electricity is turned off, all data is lost Copying between drive and memory is slow, so a larger memory may mean less copying and thus faster-running programs More memory (RAM) means the computer will run programs faster.
keyboard
input device, Keyboards were among the earliest computer input devices, 40 words per minute is average, uses electrical circuitry, The most common keyboard arrangement is known as a QWERTY its not the best and An arrangement for faster typing The keyboard arrangement was created in the days of typewriters, when fast typing could make keys get stuck.(the Dvorak keyboard) exists
Speech input
involves a user speaking into a microphone, 2010's with the advent of smartphones whose usage isn't amenable to typing (no keyboards, usage often while walking/driving, etc.)
server farm
is a collection of thousands of servers, typically located in large buildings specially equipped to provide electrical power, cooling, physical security, and accessibility for repairs. Some such buildings are as large as a football field, and thus server farms are often built in remote areas where land is cheap. A server farm may use large amounts of electricity, not only to power the servers, but also to cool the servers. Ex: 2,000 servers, each requiring 500 watts, requires 2,000 * 500 = 1 megawatt of power. Thus, server farms are often built near cheap electric sources, such as near a river having a hydroelectric power plant.
IMAP(Internet Message Access Protocol)
is a common protocol for retrieving email messages via the Internet, An IMAP server's name commonly starts with imap, as in imap.gmail.com.
embedded computerالكمبيوتر جزءا لا يتجزأ من
is a computer embedded inside some electronic device, like inside a car. In the 1970s, devices like washing machines and coffee makers had computers embedded, enabling new functionality like a coffee makers that starts brewing automatically in the morning. In the 1980s and 1990s, hundreds of electronic devices became heavily computerized, like televisions, copy machines, cars, jet aircraft, cameras, and more. For example, today about 25% of the cost of a car is for its computers, and those computers involve large programs with many millions of instructions. Today, billions of embedded computers are manufactured every year, whose costs range from pennies (computers in toys, greeting cards, cheap calculators, etc.) to millions of dollars (computers in jets, satellites, robots, factories, etc.).
server
is a computer that delivers (serves) items like web pages, documents, or videos to other computers over a network, typically having no keyboard or screen. Servers are usually kept in special closets, labs, or even warehouses; most people have never seen a server. Servers are usually fast, but large, costly, and power-hungry.
Wikipedia
is a free, online encyclopedia composed of crowd-sourced articles, begun in 2001. The name Wikipedia is based on a combination of the words "wiki" and "encyclopedia".
Pythonالثعبان
is a high-level programming language, increasing in popularity due in part to being easy to learn, to being freely available, and to having powerful high-level data-processing operations.
USB flash drive
is a non-volatile storage device that a user can connect to a computer via a USB port. USB flash drives are popular for transferring items among computers, like videos, photos, or documents. Flash is a particular kind of non-volatile storage technology with the feature that large blocks of data can be erased simultaneously (in a "flash"). Many solid-state drives also use flash.
smartphone
is a pocket-sized mobile phone that also has computer functionality, able to run various applications like web browsing. Smartphones tend to be low-cost, small, consume little power, but slower-running than other computer types.
data projector عرض البيانات
is a portable projector that displays an enlarged image from a laptop onto a screen. Portable or ceiling mounted projectors are available. Early data projectors weighed more than 40 pounds, and used CRT technology to display monochrome images. Data projectors today weigh just a few pounds and use DLP or LCD technology.
high-level language
is a programming language having higher-level instructions than assembly language, enabling greater programmer productivity. An example high-level instruction supports a formula, like C = (5/9) * (F - 32), which converts Fahrenheit to Celsius. The first mainstream high-level language was Fortran, from IBM in 1957, short for Formula Translation. A program called a compiler (مترجم ) converts a high-level language to assembly/machine language. Tens of high-level languages have been developed. Popular languages today include C, C++, Java, Python, and Javascript, each with different strengths/weakness and for different purposes.
mouse
is a small device that a user can move on a desktop to cause a mouse pointer to move on a screen, and that has one or more buttons that can be clicked to select objects. some have a wheel for scrolling, looks like a real mouse, connected via usp
is a social network site whose users send and read short 140-character messages called "tweets." The 140-character limit came originally from that limit imposed on cell phone text messages, where early tweets were sent/read. Twitter was created in 2006, in part by New York University student Jack Dorsey. Part of Twitter's popularity stems from short connections with people throughout the day, including not just with friends/family but with celebrities like Ashton Kutcher (an early and avid tweeter), who tweet on what they just did, how they feel, etc. User can choose to follow other users, or to follow specific discussion topics. A hashtag (ex: #GlobalWarming) labels a tweet as belonging to a particular discussion topic, such that users can receive tweets on that topic. Such persistent connectivity with a network of people was not available previously. Today, tweets can include photos and other media, beyond just text. Companies, politicians, celebrities, and others use tweets to make public announcements or to respond to news events. According to Twitter.com, about 500 million tweets were sent per day in 2015. Twitter's user base is large but thus far revenues are not as big as other Internet companies. Most revenues come from advertisements shown to users.
is a social networking site intended primarily for professionals to share background and qualifications with other professionals and with companies, akin to an online resume. A user creates an account and then connects with other users. A common LinkedIn usage is for a user to search their network of connections for contacts at a particular company of interest (perhaps for a business deal), or for people with particular skills (perhaps as a potential hire). LinkedIn's revenues are not primarily from advertising. Rather, 1) in 2013, more than 50% of LinkedIn's revenues came from companies paying to have access to lists of users, typically for recruiting purposes. 2) 25% came from advertising to users. Another 3) 20% came from user's upgrading from a free account to a premium account that yields special privileges (like sending a message to a user to whom one is not yet connected) and information access.
graphics processor معالج الرسومات
is a special CPU chip whose hardware is specially designed for fast graphics and video processing. Many computers, laptop, tablets, and smartphones today come with built-in graphics processors.
tablet
is a specialized portable computer typically about the size of a book with the size being mostly the screen, which is used for both output and input. A book reader is a tablet specialized for reading books, typically having an ultra-low-power paper-like display.
transistor
is a switch that can be switched on to let electricity flow from a first to second wire, or switched off, controlled by electricity on a third wire. A transistor is like a light switch, except turning the switch on or off is done electronically rather than by a human hand. A fingernail-sized IC has millions of transistors, each transistor so small as to be invisible to the naked eye.
Assembly language لغة التجميع
is a textual human-understandable representation of a machine language's 0's and 1's, as in: Add M[5] M[6] M[7]. A program called an assembler automatically converts an assembly language program into machine language.
wiki لتحسين
is a website that enables collaborative development of content. Anyone can create, edit, or improve a Wikipedia article. In 2012, Wikipedia had about 2 million volunteers worldwide, actively contributing to over 35 million articles, appearing in more than 280 languages (Source: Wikipedia Statistics). Wikipedia is usually among the top-ten most widely-visited websites in the world. A Wikipedia article is often among the first results of a web search.
Crowdsourcing
is an approach to developing content that involves having the users (the "crowd") be the contributors, rather than using highly-paid professionals. Wikepedia's crowdsourcing approach not only enables Wikipedia to be free, but also has led to far more articles than found in professionally-produced encyclopedia
log scale a (logarithmic y-axis),
is commonly used, where each y-axis tick-mark is 10x greater than the previous.
is the most widely-used social networking site, focused on connecting friends who share items like photos, videos, thoughts, invitations to events, and more. A Facebook user creates an account, and then asks existing users to become friends (and accepts other users' friend requests), after which the user can post items for friends and can see friends' posts. Facebook was developed in 2004 by Harvard student Mark Zuckerberg, initially for connecting Harvard students. Additional universities were added during the subsequent two years, first Stanford, Yale, and Columbia, then most U.S. and Candian universities, and then more international universities. In 2006, Facebook became available to anyone over age 13 with an email address. In terms of users, Facebook is one of the fastest growing large companies in history, with over 1 billion monthly users in 2014. Facebook's 2014 revenue of $12.5 billion are primarily via advertising to users.
inkjet printer طابعة نافثة للحبر
sprays small drops of ink to create text and images. A motor moves the printhead back and forth across the paper, and pauses for a fraction of a second to spray ink at the appropriate location.
computer monitor شاشة الكمبيوتر
stand alone output device that displays text, images, and video on a screen. Laptops, smartphones, and other mobile devices have an integrated screen to display information Displayed text and images consist of rows and columns of colored dots, each dot known as a picture element or pixel. Pixels produce a wide variety of colors by varying the ratio of red, green, and blue.
computer's drive
stores data even after electricity is turned off. Thus, items like programs, documents, photos, and videos are stored on the drive./ Accessing a drive is slower than accessing memory More drive (storage) means the computer can store more videos, photos, documents, etc., when electricity is off.
In 2010, most movie and TV show
streaming was done using a computer like a desktop or laptop PC. However, as streaming grew in popularity, small inexpensive boxes to stream movies from home WiFi to a TV became popular, such as Apple TV, Google Chromecast, Roku, and Amazon Fire. Furthermore
mainframe المركزية
this types had faded away, which was a large centralized computer common in the 1950's-1980's that perhaps hundreds of people shared, often accessed through tens of connected keyboard/screen combinations called "terminals."
cache (pronounced: cash) مخبأ
to provide ultra-fast access to the currently-needed instructions and data.For faster-running programs, many CPUs internally have an additional small fast memory and only occasionally has to copy needed items between memory and cache. Thus, a larger cache results in faster-running programs due to less time spent copying, but cache is relatively small because a CPU chip has limited space.
Touchpads
use small electrical signals that are affected by human skin because skin conducts electricity (due to skin's internal moisture), so touching with a fingernail, pen, or gloves may not work; touching with a wet or sweaty finger may yield wild mouse pointer movements because water conducts electricity.
Friendster
was one of the first large social networking sites, started in 2002, mostly for gamers. Inspired by Frienster's success,
Accessing a drive is slower than accessing memory.
when a CPU runs a program, the CPU first copies the program and other needed data into memory, and runs the program from memory. Memory is expensive and thus smaller than drive, so might only fit a part of the program and data. Copying between drive and memory is slow, so a larger memory may mean less copying and thus faster-running programs.
loop instruction
which repeats the loop's subsequent instructions a specified number of times. Those subsequent instructions must be indented with a tab. range(1,9) will cause the loop's instructions to run 8 times, assigning variable i with 1, then 2, ..., then 7, and finally 8 (upon reaching 9, the loop terminates).
Audio streaming sites can be broken up into the following categories:
1) Radio streaming: Users listen to live radio broadcasts streamed online. Ex: Apple Music, iHeartRadio, NPR, ESPN radio 2) Playlist streaming: The site puts together songs created based off of an artist, song, or genre. Ex: Pandora Internet Radio, Last.fm, Spotify, Apple Music, iHeartRadio, Amazon Music, Tidal 3) On demand streaming: Users specifically choose which songs or albums to listen to. Ex: Spotify, Apple Music, Amazon Music, Tidal, Rhapsody Song Audio streaming services can often be used for free, but will include advertisements during the stream. Users can remove ads by subscribing to the service, which involves paying a monthly or annual fee. Some music streaming sites, like Pandora and iHeartRadio, attempt to make personalized playlists by giving users the ability to rate songs via a thumbs up or a thumbs down. If a song receives a thumbs up, similar artists and songs are added to the user's playlist. If a song receives a thumbs down, the rest of the song is skipped and the song is removed from the playlist.
Basic parts of an email message.
1) To The main recipient or recipients. 2)The cc (carbon copy) email field indicates additional recipients: People to whom the email isn't directly intended, but who may want/need to see the email anyways.cc 3) The bcc (blind carbon copy) email field indicates additional recipients whose email addresses will not be revealed to any other recipients (neither the To, cc, or bcc recipients). 4) The subject email field summarizes an email's topic. Tip: Subjects should be precise. Ex: "Question regarding Nov. 14 visitors" is preferred over the imprecise "Question" or "Visitors". Tip: Distinct topics should be in distinct emails, to avoid topics being overlooked or hard to find later. 5) The body of an email contains the main content. Tip: A short body is more likely to be read. Tip: Putting key points first helps ensure key points are read. 6) An email auto-signature is text automatically added to the end of an email, typically including a person's name, position, company, and/or contact information
Shrinking circuit size means
1)engineers can build more complex CPUs that do more computations per clock tick. 2)Computer speed also improves 3)can add more cache on chip 4)put multiple CPUs on one chip 5)memory chips can store more bits, improving speed due to less time spent copying data to/from a drive. Moore's Law clearly cannot continue forever. One reason is that circuits eventually cannot be shrunk further, as atoms require some minimum wire width, for example. Even before that limit is reached, another reason is electrical power consumption: Too many switching transistors on a chip generates excessive heat that can damage an IC, and consumes battery too quickly. Thus, engineers have not continued to increase clock frequencies, which instead have stayed around 1-3 GHz for much of the 2000's.
How much drive does the computer have?
500 billion bytes. So the computer has over 100 times more drive than memory.
clock frequency
A clock's ticks per second / A faster clock means faster running programs, but more electrical cost, more heat circuit's switches/wires limit the clock's switching speed.
non-volatile غير متطاير
A storage device that stores data after electricity is turned off Hard disk drives and solid-state drives are non-volatile memory is volatile.
YouTube
is the most widely-used video-sharing website, which allows users to upload videos, supports easy search of videos, and suggests other videos related to a watched video. YouTube was started in 2005 by three former PayPal employees, grew rapidly, and was purchased by Google in late 2006 (for $1.65 billion in stock). In 2013, YouTube accounted for about 18% of all Internet traffic, second only to Netflix's 30% Video sharing sites earn substantial revenue through advertising. Some ads are text ads placed near videos. Others are short videos that play before the actual video plays. YouTube's ad revenues were about $1 billion in 2014 (Source: Wall Street Journal). By associating a Google AdSense account with a YouTube account and activating a video for "monetization," a video poster can earn about $1 to $3 per 1,000 views; a video that gets 1 million views thus might earn the poster 1,000,000 views * (2 dollars / 1,000 views) = 2,000 dollars.
Hardware
is the term for the physical parts of a computer CPU: Hardware that runs program instructions and controls other hardware. CPU is short for central processing unit. Memory: Hardware that stores data. Memory is also called RAM, short for Random Access Memory. Keyboard: Hardware for input that allows a user to type characters. Screen: Hardware for output that displays characters and images to a user.
software
is the term for the programs (the 0's and 1's) that instruct the computer what to do
A PC (personal computer, aka desktop PC)
is typically used by a few people in a home or office, includes a keyboard and screen, and runs various applications like office productivity, web access, games, etc. A laptop is a portable PC, smaller/lighter than a desktop PC, using less electrical power, and operable from battery power.
One gigahertz or 1 GHz
means 1 billion ticks per second
Streaming
means to play media directly from the Internet in a web browser or other app without ever storing the video on a device. In 2014, streamed video accounted for more than half of all Internet traffic, mostly from Netflix and YouTube.
plasma
monitor consists of hundreds of thousands of tiny gas-filled cells The cells are the subpixels and pixels used to create images. Cells glow and emit red, green, or blue when voltage is applied. Plasma technology eliminates the need for an electron gun, and instead utilizes a grid of electrodes to control each cell Thus, plasma monitors are thinner than their CRT counterparts. Plasma monitors are typically larger and have more contrast compared to an LCD monitor. The drawbacks of a plasma monitor is the higher cost, higher power consumption, and lower durability.
CRT (cathode ray tube) أنبوب أشعة الكاثود
monitor houses an electron gun at the rear of the monitor, which emits a high-speed beam of electrons toward a vacuum tube located at the front of the monitor. Areas of the vacuum tube hit by the electrons glow, and emit red, green, and blue light based on the type of phosphor coating. The beam sweeps back and forth 50 to 60 times a second to continuously display an image on the screen. CRT's were large and heavy.
Apple's iTunes
per-item purchases). Streaming video has become a serious competitor to traditional, cable, and satellite TV.
Vimeo
popular video-sharing website which tends to host more professional-looking videos. Vimeo was started in 2004 by entrepreneurs Jake Lodwick and Zach Klein. Other sites where users share video include Facebook, Vevo, Instagram, and Twitter.
color printer
prints text and images in a wide range of colors, and typically contains cartridges for cyan, magenta, yellow, and black. Higher end systems may contain additional color cartridges Some manufacturers sell printer hardware at a loss because profits are obtained through replacement ink cartridge sales.
monochrome printer طابعة أحادية اللون
prints text and images in varying tones of black
printer
produces output on a physical medium, such as paper, photo paper, glass, canvas, and more. The most popular types of printers are inkjet printers and laser printers.
retina display عرض شبكية العين
s a brand name for an LCD display with higher pixel densities.
LCD (liquid crystal display) projector
shines light through a prism to separate red, green, and blue light. Small LCD panels control where the red, green, and blue light can pass through. The separate colors are then combined into a single image and displayed on a screen. lamp > prism > LCD panels > lens > screen
DLP (digital light processing) projector
shines light through a spinning color wheel that passes red, green, and blue light to a chip with thousands of small mirrors. The mirrors tilt and reflect the light to display colored pixels on a screen. lamp > spinning color wheel> mirrors chip > lens > screen users typically store data on a laptop and then connect a laptop to a projector through a VGA or HDMI connector to project text or video. Newer data projectors enable users to store data on a thumb drive or smartphone and connect devices to the projector with built-in ports or through adapters.
social networking
site connects people, via common interests, backgrounds, real-life connections, etc. Such sites typically support ways for a user to add new connections, to post information for a user's connections to see, to see information posted by a user's connections, and to contact connections individually. Some sites focus on connections between friends, others on connections between professionals. growth starting in the early 2000's, contacting other people via the Internet was primarily via direct email between individuals
