Comp Apps

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Top Level Domain Names

Top Level Domains - When the domain system was set up in 1985, it only recognized 7 top level domain names (com, edu, gov, int, mil, net, and org) int is for international orgs like nato and the UN mil is for military - The original top level domains except int, apply to organizations in the US - Additionally, a set of mnemonic two letter country fomains were chosen . these allow domain names to be grouped by their country of origin. - The top level domains were expanded in 2000 to include biz info name travel and others

Going deeper in a folder

- Is the html and the file are in the same folder, no need to do anything. Href=lala.html - If the file is in a different folder href=differentfolder/lala.html - If the file is in the folder in a different folder href=thefolder/differentfolder/lala.html - Rule is that to refer to pages deeper in the file hierarchy, give the navigation paths to them. Path begins where the file was made Referencing images is the same Differentfolder/apic.jpg

Decimal to Binary

Divide by 2, remainder from bottom to top is answer -- then convert to letters if necessary

Marking links with anchor tags

2 parts to a hyper link Anchor text (the text that the user sees and will be clickable ) Hyperlink reference (the url of the webpage the computer links to) <a href= "____" > text that will be highlighted </a>

ISP

- ISP sell connection to the internet - Phone companies, cable companies, there are thousands - Most home users connect to the internet by ISPs - How an ISP connection usually works ISP company gives you a modem for your house Modems convert the bits a computer outputs into a form that is compatible with the carrier. These signals are sent to the carriers business where they are converted (via another modem) into a form suitable for the server that connects to the Internet via the Internet Gatewau. the digital subscriber line (DSL or ADSL, for asymmetric DSL) and cable (the same people who bring you TV) are two very common service providers. - When you use your smartphone, it has a modem for connection to the so called wireless network such as the 4g network provided by phone carriers, its radio signals behave just like the orange line to connect you to the internet

Authoritative Name Server

- If your DNS server never heard of a certain web address, some computer knows its IP address. That computer is the authoritative name server for the domain that that website is in, which is the si domain. - Every domain on the internet has one: a single computer knows the IP address of all of the computers in tis domain - This computer is the authority - All your DNS needs to do is ask the si-ANS for the IP address of ___, get the answer back and add the pair ____ and the ip address numbers to its list. - This is a solution that will always work Move along the domain name in the URL (right to left) asking the authoritative name server at each level what the IP address is for the ANS in the next level down. When you get to the last ANS, presto, it knows the answer.

Consistent Interface

Vendors that make a number of applications tend to keep the same common set up, such as icons and menus. - Microsoft word, power point and excel all have similarities - App store applications have similar characteristics too. • FundameConsistent Interface • ntal Similarities - Old desktops - File and Edit Menu - Newer applications- File and Edit may be a use a ribbon (Microsoft) , a collection of icons, or double tapping (smartphones) - No matter how they are shown, many applications support these operations: File: new, open, Close, save, save as, page, set up, print etc Edit: cut, copy, paste, undo, redo, select all, find, replace etc - These familiar operations are frequently available for fundamental reason. - Why? Software companies reuse the same code but also If operations you use in one application are needed in a different application, making the look and work the same helps you learn and use the second application. Main reason for consistency- certain operations are fundamental to processing information no matter what the application. They weren't thought to be cool add ons, the applications require them. vendors must include them and once they are there, making them behave consistently is easier for them and more convenient for you Clicking and Blazing - Consistency provides a strong sense of familiarity when we see a new app. Once we install it, we immediately do 1. Click around- exploring to see what features are available. You know intuitively that you will recognize many features from other applications justified by the consistent interface 2. Blazing away- going boldly where you've never gone before . trying the application assertively, you cant break anything its software.

Boolean values

'true' or 'false' values; every computer decision results in a Boolean value

text editor

(computer science) an application that can be used to create and view and edit text files

Digital Signals

(discrete) Computers have a circuit that only enables them to only be able to count 0-1 (on/off) -- this circuit is a transistor

required tags

- <!doctype html> - <html> - Divided into 2 parts. Head and body - Head place to describe characteristics of the whole page. Doesn't typically contain content. But title. - <meta/> tag Singleton <meta charset="UTF-8"> <meta name="description" content="Free Web tutorials"> <meta name="keywords" content="HTML,CSS,XML,JavaScript"> <meta name="author" content="Hege Refsnes"> - Body tag - content of the web page - Doesn't have to be a paragraph, can be a picture. - Charset = character set - UTF-8 Unicode Transformation Format 8 bit version

Headings

- <h1> level one, the highest. </h1> - Large letters on a new line - H1 - largest - H6- smallest - They get less strong and less bold

wireless networks

- A variation on the LAN connection and is often referred to by its protocol name 802.11 - It is the technology used inside coffee shops and homes - Router- it is physically connected to an ISP's modem connected to the Internet and is capable of broadcasting and receiving radio frequency signals. - The router and any computers within signal range (with their wireless communication turned on) participate in a network based on the Ethernet principles described earlier. - The router relays internet requests for the participating computers.

Operationally Attuned

- Another term related to extracting concepts and processes refers to being aware of how a gadget works - Means to apply what we know about how a device or a system works to simplify its use. - Knowing all caps, screws and nuts loosen by turning left and tighten by turning right. - Knowing this rule helps is when a lid or nut is stuck - Being operationally attuned makes us more effective. - Thinking about how computation works makes it simpler to use - Asking questions on how things work and Using what we learn by thinking of the answer, we will be more successful at applying IT

Tags for bold/ italics/ paragraph

- Bold - Italic - Paragraph - You can use more than one at a time, by properly "nesting" the tags. (word inside all the tags) <><><> word </></></>

DNS

- Figuring out the IP address for your domain name is the dask for Domain Name Systems servers (DNS) - All internet connected computers when they are first set up and connect to the internet are given the IP address of one or more DNS servers - These machiens look up domain names you ise and find the corresponding IP addresses. - They just have a list of [domain name: IP address pairs] - Given a domain name, the DNS server returns the address to your computer, which continues with connecting you to the site. - There is no master list of all domains on the internet - If your DNS server never heard of a certain web address, some computer knows its IP address. That computer is the authoritative name server for the domain that that website is in, which is the si domain. - Every domain on the internet has one: a single computer knows the IP address of all of the computers in tis domain - This computer is the authority - All your DNS needs to do is ask the si-ANS for the IP address of ___, get the answer back and add the pair ____ and the ip address numbers to its list. - This is a solution that will always work Move along the domain name in the URL (right to left) asking the authoritative name server at each level what the IP address is for the ANS in the next level down. When you get to the last ANS, presto, it knows the answer.

Mark Up Validation Service

- Have your webpage automatically validated to make sure it works - The service tells you where your mistakes are and whats not proper. - it is a website

Herman Hollerith

- Herman Hollerith was generally credited with the first "production" application of digital information Knew processing data by hand was slow Invented a machine to tabulate data based on holes punched in cards How to Digitize a Punch Card A punch card is moved toward the left by a metal roller. Above the roller is a bundle of metal wires called a brush. When the hole moves over the roller, the brush pokes through the hole and touches the roller, making an electrical connection. -once the machine senses the presence of the hole, it passes the signal n to another part of the machine for further processing. Processing the Information Once detected (like the number 2 or 1), the machine will count the cards using its odometer, which counts cards like a car counts miles. By first separating the input into the two stacks, and then running each stack through the machine again to count them, the number of the two different qualities in the input can be determined mechanically No Computer needed The device is not a computer It is a card reader and a stacker Detects the presence and absence of a hole in a card Stored Program Computers • Holleriths idea was a hit and governments and businesses adopted his punch cards and tabulating machinery idea. • Punch cards were primary digital but they weren't perfect

html

- Normally when we give a url, we expect the last item in the sequence to be a file name , such as homepage.html but it is not always necessary - Other technologies besides html are used to create webpages - Also, when url ends in slash (means last item in the path is a folder rather than a file name) the browser automatically looks in that folder for a file called index.html or index.htm - Me.com/yell/index.htm is the same is me.com/yell - It will only exist only if the person who set up the web pages and built the file hierarchy decided to organize it that way and provide the index pages. - Some people do and some people don't, but the browser will look when necessary. - Most people build hierarchys to organize their thinking and work. Because directories cost nothing, there is no reason not to use them, and it is highly recommended.

Graphical User Interface/ Metaphor

Graphical User Interface

- PARC designers introduced a graphical user interface (GUI) to replace the prevailing command line interface (CLI). - They adopted the desktop metaphor what the users see on the screen is a virtual desktop. Whole new idea of displaying docments in overlapping windows as though they were papers on a desktop, users control the position of the window over the document with scroll bars as if changing focus on the page. There were buttons, an email icon, and window clipping. - Key part was the mouse- which let users reposition their focus on the screen by pointing. - Macintosh introduced the first successful personal computer with a graphical user interface. Extended ideas from alto, adding new icons and mechanisms. Showcased the mouse for painting and drawing applications.

Synchronous Communication

- Requires that both the sender and the receiver are active at the same time. (Talking on the phone)

- There are atleast 2 advantages to storing and sending the source rather than the image itself.

- Servers do not store web pages in the form seen on our screens - Pages are stored as a description of how they should appear on the screen - When the browser receives the description (source) file, it then creates the Web page image that is displays. - There are atleast 2 advantages to storing and sending the source rather than the image itself. A description file usually requires less information The browser can adapt the source image to your computer more easily than aliteral pixel by pixel description. The description is easier to shrink, or expand in response to changes in the size of the browser winsow, than is the image itself.

White Space

- Spaces that have been inserted for readability - Created with spaces, tabs and new lines (return or enter) - HTML ignores white space - The browser turns any sequence of white space characters into a single space before it begins processing. - All white space is converted to a single space. - <pre> preformatted tags - displays as it appears -

Singleton tags

- Tags that are not paired with an ending tag. Closing bracket is replaced by <hr/> - Horizontal line <hr/> - Break - Don't surround anything so they don't need to be paired with a closing tag

Arms Race

- The ARM is a processor specialized to be part of other systems, though its found everywhere these days. - Advanced RISC Machine - RISC—Reduced Instruction Set Computer - The value in using a computer as an embedded part of some other consumer product is that it's much easier to write code for a computer to manage the operations of, say, a microwave over or other task, than it is to design specific electronics for the functions. - Designers choose software> hardware again.

Enterprise Network Connections

- The other way to connect to the internet is as a user of a larger networked organization such as a school, business or governmental unit. - The organization's system administrators connect the computers to form a local area network (LAN) or interconnected LANs using Ethernet. - These local networks- collectively known as an intranet support communication within the organization, but they also connect to the internet by gateway. - With either method- ISP or LAN - you usually end and receive information across the Internet transparently- without knowing or caring which method is used.

Asynchronous Communication

- The sending and receiving occurs at different times - (postcards, text messages) - Listening machines and voicemails make synchronous into asynchronous.

Escape

- Using brackets as text is prohibited - Escape symbol = the ampersand &abbreviation; - < displays as < - > displays as > - Accent marks need escape symbol too - é e tick mark &Egrave E tickmark - &ntilde n swivel tick mark - Each symbol can be written as a number too - &#number

additional formatting tags

- We don't need to memorize all the tags. - - <emphasized> - - goes to next line - underlined - subscripted (bottom) - superscripted (top) - <q> quote - <s> line through it - <ins> text inserted into the doc. (underlined and inserted) - <block quote>does not go inside p tag

Domain names

- We use domain names to refer to computers, rather than their IP addresses - The Domain Name System (DNS) is hierarchical structure we use to name computers. - Spiff.cs.washington.edu - ,edu is a top level domain name used by educational organizations - All of the computers at the university are apart of the Washington domain, within the edu domain - This pattern continues - This makes it easier to remember computer names Peers - Domains at the same level in the hierarchy are peers of each other. - Other computers that are used in the cs department are peers of spiff, because it is a member of the exact same domains. - Princeton.edu is a peer of Washington.edu - Edu is a peer of other top level domains such as com or org .

world wide web

- Web servers- some of the computers connected to the internet are this. They accept http requests from browsers running on other client computers and return files that the browsers can display. - Together, these Web Serves and their files define the World Wide Web - WWW

Protocol

- When requesting a page- your browser is a client asking for a file from a Web server computer using the familiar (URL - Universal Resource Locator) - The URL has 3 main parts 1. Protocol The http: // part Hypertext transfer protocol - tells the computer how to handle the file There are other ways to send files such as ftp, File transfer Protocol 2. Server Computer's Domain Name The blog.ucls.uchicago.edu - which gives the name or the server in the domain hierarchy 3. Page's pathname : the csts/files/2007/07/0_new_1_csci.gif part Gives the pathname saying where to find the page or other file. - All urls have that structure - In some cases, software fills in the missin parts, however, it is never a mistake to use the full form - Web browsers and web servers both speak to HTTP. - When you specify a URL in your browsers location window, you say where the information is to be found (the server's name) what information you want (the pathname ) and what protocol the two computers will use to exchange the information (http)

Processors

- more technical name for a computer. Includes the COU, a small amount of memory usually called a cache, and is connected to some input and or output devices. The main variation comes with the devices the computer is connected to, and of course, the software. -printer, microwave ovens, brakes, music players

• Types of communications by number of receivers:

1. Broadcast Communication - Involves a single sender and many receivers *radio and television 2. Multicast- this term is used when there are many receivers, but the intended recipients are not the whole population (magazines) 3. Point to Point communication - Opposite of broadcasting and multicasting - One specific sender and one specific receiver

2 basic methods to connect to the internet

1. Connection via an Internet Service Provider 2. Connection provided by a campus or enterprise network Some of us use both daily

2 solutions for a continous illusion from a computer

1. Cookies - small files stored on the client computer by the server and returned to the server with each page request. The file contains enough data from the server, such as a unique identifier, that it can connect you to earlier interactions. 2. URL Parameters - information added by a client to a URL when it connects to the server. You notice this for example when buying airline tickets Flybynite.com/buytix.php?trip+vdfkjndfkvjnszkfn It is the information following the question mark o Both techniques allow the client to send enough data to the server for it to figure out which of its recent interactions was yours and to give the illusion of having stayed connected. o Both techniques are common o Cookies are both convenient and dangerous

bit/byte and mb gb and kb conversion

1024 mb = 1 gb 1024 kb= 1 mb 8 bits= 1 byte 16 bits = 2 bytes = 1 Hexa decimal system 2 bits= binary system

pathname

3. Page's pathname : the csts/files/2007/07/0_new_1_csci.gif part Gives the pathname saying where to find the page or other file. - All urls have that structure - In some cases, software fills in the missin parts, however, it is never a mistake to use the full form - Web browsers and web servers both speak to HTTP. - When you specify a URL in your browsers location window, you say where the information is to be found (the server's name) what information you want (the pathname ) and what protocol the two computers will use to exchange the information (http)

server

A computer in a network that provides access to other computers in the network to programs, web pages, data, or other files and services, such as printer access or communications access. a computer or computer program that manages access to a centralized resource or service in a network.

browser

A program that allows the user to find and view pages on the world wide web.

Transistors

Computers have a circuit that only enables them to only be able to count 0-1 (on/off)Computers have a circuit that only enables them to only be able to count 0-1

Algorithm

AFUNCTIONING SET OF INSTRUCTIONS, THAT MUST END, WHILE GIVING OUT INPUTS AND OUTPUTS. Precise enumeration of instructions to execute, to solve a specific problem. The underlying goal is to find the best possible way to do something effectively and efficiently. Not all algorithms are inherently efficient nor effective. A slow but SMART computer might be able to do something faster than a faster, but NOT-SO-SMART, one. This smartness, is the algorithm, hence, the process to be used to solve a problem. • Specific/systematic set of instructions which you are going to follow to produce an output (a certain output) - Each line is a set of instructions to follow • Need to use machines in a smart way for an efficient performance - We wanna be smart on how we use our resources - That is why we need good algorithms be aware of our scarce resources, if we were wasteful it does not make any sense

absolute path names vs relative

Absolute- different site Relative- on the same server

CSS

Cascading Style Sheets

Hex to Binary

Chart

Perfect Reproduction

Data can be copied EXACTLY the same way over and over, with no floating point errors (0 or 1 are discrete, while 1.11111100045678... is not) - Computers only encode information as 0 or 1. - We call this digital information - Relying on only 0 and 1 means that digital information has many great advantages. - It can be perfectly reproduced or replicated. - Data can be copied EXACTLY the same way over and over, with no floating point errors (0 or 1 are discrete, while 1.11111100045678... is not An exact duplicate - By using a sequence of 0s and 1s, we can make another copy simply by duplicating the sequence - Bc it is digital, we can check to make sure the two sequences are identical, verifying no mistakes - Computer systems make such checks continually. DIGITAL ENCODING--> there are only a limited number of choices. (Copy, Paste, save and replace all)

Decimal to Hex

Divide by 16, remainder from bottom to top is answer

colors encoding

Each color is represented with 8 bits = 1 byte. A PIXEL is made of the combination of 3 colors, Red, Green and Blue - RGB Then, each PIXEL has 24 bits = 16,777,216 different possible combinations. (256 * 256 * 256 possibilities) RGB(0-255,0-255,0-255) = 2 24 = 16,777,216 colors White is the total saturation of all color's intensity: RGB(255,255,255) Black is the lack of any light intensity: RGB(0,0,0) when creating web pages, colors are in Hex Form

Software Stack

Each part ... ... serves a very specific purpose. ... can be swapped for newer/better ... is one piece in a bigger system ... receives input, processes it and produces output for the next component, whose input will be said output for then... you get the picture. - AppsOS AppsOS KernelHardware • Know we consume the layer undernieth • The app needs something more complicated to work, which is the layer right underneath it • Hardware- machine where all that logic is going to run • Point is - the person does not necessarily need to know or care what is occurring to make the app run (facebook, snapchat) • Software stack is an Input (vv) then Output (^^) • Each part relies on the one undernieth (layers) - Needs everything the bottom block offers • Signals goes then comes back The two key points about layered software development are: 1. Programmers can use the software in these boxes without ever understanding how those programmers work, beyond knowing the proper way to use them. They are building on the work of thousands of other programmers, who have contributed to these layers. 2. As technology advances, more boxes will be included (this figure is not exhaustive) and more layers will be added. For example, before the creation of the Android smartphone much of this software- the database code, for example, already existed. Software gets more and more complicated, and sophisticated based on combined efforts of programmers We build on what we already can do (abstraction)

Numerical Basis

Easily manipulated with base-2 math

Hex to Decimal

First -- convert to Binary Then -- do binary to decimal (number x 2^(decimal place)

Binary to Hexadecimal

GROUP INTO 4, number x 2^(decimal place) . if >9 use letter

meta data

It is of utmost importance, we can distinguished between the actual data, and information about this one. Information that can be entered about a web page and the elements on it to provide context and relevant information to search engines. Data that describes other data.

Main board

Houses and connects ALL components

Analog

How many values can be found between 1.1 and 1.2? Infinitely many. Continuous .

HTML

Hyper Text Mark up Language In addition to the words and pictures on a web page, hidden formatting tags in the file describe how the page should look. Html5 - tags must be lowercased Tags- used for formatting. Words or abbreviations enclosed in angle brackets < > <__/> [this is where it starts and this is where it ends] Start tag and end tags

Basic Components of a Computer

Main board, Memory and Processing

New instance

New creates a blank instance of the kind of file the application create New information, a blank template • Familiar new command is found under the File Menu. It creates a "blank" instance of the kind of information of files the application creates • "blank information" - All information is grouped into types- based on its properties. - Any specific piece of information (an image, document, or month) - is an instance of its type - "new" or "blank" is simply the structure without any properties or content filled in. - It is a new instance, ready to receive content.

Data

Quantities, characters, or symbols on which operations are performed by a computer, being stored and transmitted in the form of electrical signals and recorded on magnetic, optical, or mechanical recording media.

Memory

Remembers current and previous data - 2 types 1. Solid state drive - disk that saves information, many times faster, newer technology than hard disk. (slick) 2. Hard disk drive (thick, disk on top, rover spins) - Persistent data Ram - volatile, whatever goes into that, it goes away. Makes computer faster, more programs running at the same time So much faster, but smaller memory. While big memory is slower

Metaphors

Representing new ideas, concepts or functionalities by associating them with over-familiar concepts. - We get tremendous assistance from product developers who create technology that minimize learning time. - Matching our expectations is often (and correctly) carried to an extreme - Ex- increase/decrease situations - low is usually left slider or counter clockwise on a dial, and high Is the opposite - When designers make the technology work this way, it reinforces this convention and fulfills our expectations more completely. - Metaphor- an icon or image or a concept used as a representative of or symbolic of a computation. When designers make technology, they use metaphors to help users know how to operate their devices without reading a manual. (no one wants to read the manual) Metaphor idea is most widely used and most apparent in software - Ex- controlling volume. Metaphor for the operation of increasing or decreasing something else that may not be volume.

User Experience

The feeling a user has when interacting with a system. For instance, how easy was to manipulate the application in general. "Yes, it does look awesome, but it just ate all my files because I accidentally tapped on a huge green button on the middle of the screen..." Terrible UI leads to an even worse UX

Abstraction

The intuitive simplification of a concept. We extract the global and key ideas of an entity, in order to explain it. How to accelerate in a car: Push the pedal, turn the pivot, pull the throttle wire, allow air to go through the butterfly valve to reach the engine..... NO. All that knowledge has been abstracted to us... we just need to know which pedal does what. The same principle applies to Computer Science and the software building stack. the removed concept that is usually expressed in a more succinct and usually more general form - Being able to tell the difference between important and unimportant details is essential to understanding - The intuitive simplification of a concept. - no need to go in depth of what is happening. Just need to know the key idea. - The idea- abstraction has meaning beyond the story. The point of repeating the parable is to convey an idea that applies to many situation. (abstracting the main lesson of the tortoise and the hare) - In computing - separating the relevant from the irrelevant, and applying the abstraction to other cases, are both essential

User Interface

The way a user interacts with system and how this responds to such interaction. For example, colors, contrast, buttons interaction, touch feedback, hover-on feedback, etc...

Boolean logic

Using the base-2 numeric system, simplified logic can be easily applied to gate controlled circuits- Combining words and phrases using the words AND, OR, NOT and NEAR (otherwise known as Boolean operators) to limit, widen, or define your Internet search. TRUE OR FALSE .

Multimedia Encoding

We will measure colors based on their intensity. 0 being nothing and 1 being intensity maxed out.

Degradation Recovery

When a signal degrades, it can be fully recovered, as opposed to an analog, which can not.

Information

When data is processed, organized, structured or presented in a given context so as to make it useful, it is called information.

compose and check

check your typing and tagging very often. productive to work with two windows open, your text editor and your browser for checking.

Digitizing Information

data represented using numbers (ISBN #s etc). - Getting a machine to read digital information was the breakthrough

Fluency

hands on study. you have to do it to learn it. reading component and lab component. 2 programs needed to html, browser and text editor.

Ethernet

main technology for local area networks and is appropriate for connecting all computers in a lab or a building. - Radically different from the internet, buts its equally easy to understand. Ethernet, the set up • The physical setup for an Ethernet network is a wire, wire pair, or optical fiber the channel (it winds past a set of computers) • Engineers tap the channel to connect a computer, allowing it to send a signal (drive an electronic pulse or light flash onto the channel) • All computers connected to the channel can detect the signal, including the sender. • Thus, the channel supports broadcast communication. Ethernet, the protocol • When a computer is sending signals on the channel, all of the computers listen to it only one computer typically keeps the transmitted information • A pause indicates that the end of transmission when no computer is sending signals and the channel is quiet • A computer wanting to transmit starts sending signals and, at the same time, starts listening to the channel to detect what is being transmitted. • If it is exactly the information the computer sent, the computer knows it's the only one sending and it completes the transmission. • If the computer's signals are mixed in with signals from one or more other computers, it notices the garbled message and stops transmitting immediately. • The other computers stop too • Each machine pauses for a random length of time • The computer that waits the shortest length of time beings sending, and if there are no conflicting computers, it continues. • If not, the colliders repeat the process • Ethernet scheme is decentralized and there is no schedule or plan • Each computer listens to the channel and if its quiet, its free • The computer transmits unless some other computer starts at the same moment. When that happens, both computers back off for a brief random amount of time and then try again

Binary to Decimal

number x 2^(decimal place)

local. relative

on the same server.

absolute

other website

pixel

picture element. basic picture element on a display

computer

receives data, processes data, stores data, and produces a result.

pay load

what is being send. Can be one byte, or thousands.

Feedback

when the computer responds to what you are doing, signifying that it is working. is any indication that either the computer is still working or has completed the request. - Takes many forms, depending on what operation a user has commanded. - If the operation can be performed instantaneously- so fast that a user doesn't have to wait for it to complete- the user interface (UI) simply indicates that the operation is complete. - When the operation is an editing change, like the proof that it is done is that the revision is visible and the app is ready for another command - When the effect of the command is not discernible- say when one clicks a button- then there is some other indication provided (for example, highlighting, shading, graying, underlining, color changing etc) - The most obvious forms of feedback are the indications that the computer is continuing to perform a time consuming operation. The cursor is replaced with an icon like a rainbow spinner, an hour glass, a busy spinner. - When the completion can be predicted, the application shows a meter called a progress bar. - When the operation is processing a series of inputs, the "completion count: gives the tally of the completed instances, or equivalently , the number remaining. - Always expect feedback and notice it.

IP Packets

• A computer communicates with another computer by sending an IP packet to its IP Address • Packet is like a postcard - it has the IP address of the computer being contacts and the return IP address; it also has a sequence number, a few bits for technical purposes, and a pay load. • The pay load- what is being send. Can be one byte, or thousands.

Trace Route

• Because two packets can take different routers to one destination, net working engineers record and analyze the routes packets take.

Numerical Binary Systems

• Binary | 2 | [0,1] • Octal | 8 | [0, 1, 2, 3, 4, 5, 6, 7] • Decimal |10| [0 - 9] • Hexadecimal |16| [0-9, A-F] - Used to represent very big numbers - Do not need to know log math he said

Data Encoding

• CPUs and other integrated circuits, utilize transistors to process their data • Transistors have 2 states: charged, and uncharged. How could be possible encode this states • 1 transistor * (On or Off) 2 states • 2 transisitor (On or off) 4 states • 3 transistors (On or off) 8 • Always Base ^d(how many digits you have) • Base- the number of different digits you can represent with a single digit.

Moore's law effect

• Computers have become smaller and cheaper, primarily because of amazing advancements in electronics Moors Law effect • And because they are so useful.

American Standard Code for Information Interchange - ASCII

• Each character, is represented with a value. A decimal, hexadecimal, • octal and HTML value. • This is useful mainly for two reasons: 1)Programmers around the world agreed that 97, is always, and unambiguously, an 'a' 2)it is MUCH more practical to remember, or reference, 97 than 1100001, right? 3)Each character can be represented with a single BYTE (8-bits) 4)Under the same principle, such code can be easily extended. In fact, it has been many times already.

IP Address

• IP address - (Internet Protocol Address) • Each computer that is connected to the internet is given a unique address • It is a sequence of 4 numbers, separated by dots • Ex - 134.432.2.234 • 345.32.1.5 • The range of each of the four numbers (0-255) allows for billions of Internet Addresses • Even though this is a large range, Ip addresses are actually in short supply.

IP Packet

LAN

• LAN • LAN (Local Area Network) when computers are close enough to be linked by a single cable or pair of wires, this is what the interconnection is called.

client/server structure

• Most interactions over the internet use a protocol known as client/server interaction - the simple idea is illustrated by following what happens when you browse the web • A brief encounter - When you click a web link, your computer begins the process of accessing the page for you - In that moment, the computer enters the client server interaction - You - client - Computer on which the web page is stored - server computer (that's why it is called web server) - Client refers to any situation where one computer, the client, gets services from another computer, the server. - As a result of your client request, the server sends the page back over the Internet, fulfilling the request. That completes the operation started when you clicked on the link and it ends that client/server relationship. - The client server structure is fundamental to interactions on the internet - Key aspect - only a single service request and response are involved -- very brief relationship lasting from the moment the request is sent to the moment the service is received—very short. - It only entails the client's single request for a service and the server's reply in response.

The client/ server structure

Copy /Paste

• Perfect reproduction is a property you use everyday • Copy/Paste/Edit - When editing, we have the option to create identical content directly by retyping or redrawing, or to use Copy/Paste to reproduce it from another location. - It is generally faster than entering content and the copying is perfect - All instances have the same form than entering content (perhaps to be modified by Find and Replace All- It will always hit , including spacing entered text may not match exactly. - Advanced application like spread sheets , drafting and design tools, they can be very fussy about the content and the form of the input. C/P makes no tiny mistakes. - It minimizes format mistakes • Find and Replace All - Available in many apps - We give the source content to FIND in the document and the target content to REPLACE it with - It is an "applied in all cases" version of Copy/Paste and our main interest here. • Save Typing With a Placeholder - Use F/RA effectively when you need to enter complex info again and again - Adopt a placeholder- any short letter sequence that is easy to type works as long as you remember it - At the end of your paper, do a Find on the placeholder and a Replace All with whatever you need. - Do this before proofreading - Easier and less time consuming • Placeholder Technique - Hide correct items (replace all correct text sequences with a placeholder (#) - Edit as needed (Make corrections to remaining text sequences with F/RA) - Restore correct items (Replace the placeholder (#) with the original text.

Central Processing Unit

• The electric computer saved the "Rewiring" problem. - Performs instructions stored in the computer's memory. - Hard (wires) to soft (memory bits) thus the name software. - Interprets instructions - Major advancement - Defining property of a "digital computer" --> executes commands from a computer's hardware and software; the principal computer chip that contains several processing components, which determines the computer's operating speed; the "brain" of a compute - Brain of the computer - Just like a function - Crunches data

IP packets path

• The internet is many switches and routers connected by copper wires, fiber optic cable, microwave links, radios and other technologies. • When an IP packet arrives at a switch, the witch reads the destination IP address, decides which of the routers that it's connected to will take the packet closer to its destination and forwards the packet on. • Hop - the transition from one router to the next. Many Paths • All routers and switches are connect to several others. • They can send packets to any of their neighbor routers • If a neighbors router is not working (taken offline, failed, is busy) the router simply uses some other neighbor. • As a result, IP packets headed to the same place can take different routers to their destination. Trace Route • Because two packets can take different routers to one destination, net working engineers record and analyze the routes packets take. • They use a tool called trace route • Sometimes packets have to make their way through local networks to reach the Internet Gatewat. (These IP addresses are reserved to start with 10) • Some hops can be classified as a local (physically nearby ) hop or a very long distance hop.

the internet's communication properties

• The internet supports point to point asynchronous communication. • The internet provides a general communication "fabric" by linking all computers connected to it. • Computers and the network become a single medium that can be applied in many ways to produce alternatives to established forms of communication. • The internet is like a postal system, but at electronical speed. • Skype (so fast it mimics synchronous conversation) • Two or more people can have a conversation by the rapid exchange of asynchronous messages • Multicasting is possible on the internet- groups can video chat, to communicate - via blogs, discussion boards • Broadcasting is offered on the internet- web page or you tube videos that can be accessed by anyone.

Mnemonic

• Unusual term that we use in IT and in other fiels • An aid for remembering something. • Ex - ROY G. BIV colors of the rainbow • Acronyms start out as mnemonics and end up becoming the names for things. • Thinking of mnemonic that helps us remember the details when we need them makes using technology more simpler.

WAN

• Wide Area Networks (WAN) the internet is a collection fo them. They are networks designed to send information between two locations widely separated and not directly connected.

Layered Software development

• Without the advances of software, social media, and many other things could not have happened. Layered Software Development • Software development has matured and become more disciplined and sophisticated • Software development applies a layered approach in which programs at one level apply code for the more primitive operations from lower levels, and provide more advanced facilities for higher levels. • Hardware at the bottom, apps on top.

Integrated Circuits

• is capable of receiving a signal, processing it and producing output. -Integration solved the problem of efficiently assembling computers out of transistors, resistors, capacitors and wires • "silicon technology" is was gave Silicon valley its name monolithic blocks (chips) made of silicon and closely related elements in which both active parts like transistors and connective parts like wires are fabricated together in a multistep process. - Part are connected together before they are even fully formed, this is dramatically different than manufacturing the components first and later connecting them. Photolithogry --> - Chip makers "print" the wires(and all other parts) onto the chip. - Top layer of aluminum wires - Undernieth, the layer below is a transparent layer of insulator (glass) separating the top layer of wired from another layer of wires below - The glass layer has been printed to have holes in it called contact cuts (squares at the end of the wire) so the top layer of wires can connect at the right places to lower layers.

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