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45 Cards in this Set
- Front
- Back
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define: Digital information |
data represented using numbers (such as an ISBN number) |
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What did Herman Hollerith invent/produce? |
1st production application of digital info
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what was it that Herman Hollerith invented? |
a machine to tabulate data based on holes punched in cards. First used for the 1890 US census (punch cards were used primarly for the next 75 years) |
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hardware is |
built out of wires, rollers and motors
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software |
uses memory chips |
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what is the central processing unit (CPU) |
performs instructions stored in the computers memory (software---memory bits) --defining property of a "digital computer" --solves the rewiring problem
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advantages of software vs hardware |
Programs can be... 1. can be changed rapidly 2. be much more complex being limited only by the size of the memory 3. computations are autonomous, they can run on their own |
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ENIAC was what? |
first electronic computer that used vacuum tubes |
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transistors are |
low power (less heat), extremely reliable, small in size and weight
thus, computers got much smaller and made them more affordable and have much more complex CPUs |
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intergrated circuits are |
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 |
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photolithography |
chip makers "print" the wires onto the chip |
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Moore's Law |
Gordon Moore stated that a computer of a given capacity needed fewer and fewer chips as the years went by, and therefore become cheaper and cheaper |
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ARPANet is what? |
forerunner of the internet ('69) |
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Tim Berners-Lee idea was.... |
To create an online center--later dubbed a "home page"--where everyone could access the documents,images |
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What is the software stack |
where programmers can use the software in these boxes w/out understanding how those programs work. We build on what we can already do. android phone hard ware is on the bottom and the apps on the top |
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processors (also known as computer_ |
includes... 1. CPU 2. small amount of memory (called a cache) 3. connected to some input/output devices |
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What is ARM? |
Advanced RISC machine -processor specialized to be part of other systems ---such as a microwave, designed specifically for certain functions
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programs are |
a collection of computer instructions that implement a function or action
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software is |
one or more programs...instructs the computer hardware by providing the steps needed to perform a task, like displaying a web page |
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programming is |
instructing an agent to perform some function or action by giving a step by step process ---writing a recipe is programming
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an agent is |
anything that can follow the instructions (such as the computer, or a person) |
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algorithm is a |
precise and systematic method for producing a specified result ---the recipe is the program the final dish is the algorithm |
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5 properties needed for a process to be an algorithm |
IODEF 1. Input specified 2. Output specified 3. Definite (whole process is spelled out) 4. Effective (its within the abilities of the agent) 5. Finite (agent will eventually finished the computation) |
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1. synchronous communication 2. asynchronous communication
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1. sender and the receiver are both active at the same time (telephone convo, Skype) 2. sending and receiving occur at diff time (mail, text messages)
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1. Broadcast 2. Multicast communication 3. Point-to-point |
1. single sender and many receivers (radio and TV, YouTube) 2. many receivers but the intended recipients are not the whole population (magazines, blogs, discussion boards) 3. one specific send and one specific receiver (text messages, telephone) |
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what is the internet? What kind of communication is it a example of? |
a network of networks that is point-to-point asynchronous communication |
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client/server relationship |
any situation where one computer (client) gets services from another computer (server) -operation starts when you click on the link then once you recieve that page the client/server relationship ends -computer stays connected to the internet NOT the web server |
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what are 1. cookies 2. URL parameters |
1. small files stored on the client comp. by the server (i.e. Amazon) and returned to the server w/ each page request 2. URL parameters are info added by a client to a URL when it connects to the server (info following the ? mark on the URL) |
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1. IP (Internet Protocol) address 2. IPv4
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1. is a sequence of 4 numbers seperated by dots (numbers range from 0-255) 2. consist of 4 one-byte numbers 3 |
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1. IP packet 2. payload |
1. when one computer comm w/ another comp sends an IP packet (like a postcard) which consists of a start of 12 bytes (the bits needed for technical purposes then 4 bytes for the sender and receivers IP address, 2. payload is what is being sent
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hop |
the destination from one router to the next (when an IP packet is being sent) |
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How does Transmission Control Protocol/Internet Protocol (TCP/IP) work? |
Like sending a book through the mail one postcard at a time (breaking up the book into smaller units then numbering the postcards for them to be organized once received) |
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The INTERNET is a collection of wide area networks (WANS) |
networks designed to send info b/t two locations widely separated and not directly connected (such as not a single flight from Tahiti to NYC) |
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local area network (LAN) |
computers are close enough to be linked by a single cable or pair of wires ---such as an Ethernet cable is the most common form of LAN |
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ethernet (the set up) |
the physical setup for an ethernet network is a wire, wire pair or optical fiber called the CHANNEL (supports broadcast connections) --the ehternet packet is limited to 1500 bytes and the IP packet is reduced to 1480 Bytes |
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how does receiving internet access work thruough an... Internet Service Provider (ISP) |
ISP company gives you a modem (convert the bits a comp outputs into a form) that is compatible w/ the carrier. There signals are sent to the carrier's business where they are converted (via another modem) into a form suitable for the server that connects to the Internet |
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how does wireless networking work? |
is a variation of the LAN connection has a ROUTER which is physically connected to an ISP's modem connected to the Internet and works on networks based on the Ethernet principles |
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1. domain names 2. domain name system (DNS) |
1. use to refer to computers rather than their IP addresses 2. DNS is the hierarchical structure we use to name comps --.edu is a top-level domain name --.com, .org are peers to each other
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authoritative name server (ANS) |
although your DNS hasn't never been to X website it can ask another comp for that info (which is the ANS) |
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root name servers 7 orig top level domain names |
the comps that know the IP addresses for the top-level domain are the 13 root name servers --.com, .edu, .int., .org, .gov, .mil., .net |
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caching |
act of saving info for possible reuse helps DNS servers so it doesn't have to go searching for the site again |
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redundancy |
use of multiple copies of info (such as the TLD list) |
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1. web servers 2. World Wide Web |
1. accept HTTP requests from browsers running on other (client) computers and return the files that the browsers can display 2. together these web servers and files make up the WWW |
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the internet vs the WWW |
INTERNET is made up of wires and routers connecting named computers (hardware) WWW is a subset of those computers (web servers), their files, and their services |
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URL (Universal Resource Locator) 3 parts which are...? |
1. PROTOCOL: the HTTP (hypertext transfer protocol) tells the computer how to handle the file (also is file transfer protocol FTP) 2. SERVER COMP's DOMAIN NAME 3. PAGE'S PATHNAME: saying where to find the page or other file |
