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45 Cards in this Set

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  • Back
4. Why do we care about how well a computer handles simultaneous execution?
1. Often run several programs at once doing different tasks. And how the computer does so is important
5. What is virtual memory? How does it work? Why do we care if an operating system has it?
1. Additional temporary memory. Allows more applications to run.
Disk space that is used to mimic RAM
Allows an operating system to load more programs than it can fit into RAM at once
1. From the user’s point of view, what’s the difference between running a compiled program and running an interpreted program? Why would the programmer care about this difference?
1. Compiled - A specialized program that converts from source to executable for a certain operating system.
2. Interpreted - A program, generally freely available, that reads and executes programs written in some particular language (e.g., PHP). – needs to be done everytime, reads the program into memory and executes
1. So basically compiled is an exe, interpreted needs an interpreter
3. Programmer needs to have the appropriate interpretor
2. What’s the relationship between Java and JavaScript?
1. Java is compiled to HTML and then interpreted by a web browser
2. Javascript is simply interpreted by the web browser
3. Java vs. javascriptà write program for phone, write it in java, phone can translate and run it. (smat phone)
4. Java has nothing to do with javascript (netscape makes it)
5. JavaScript- Referred to as client-side scripting
6. As opposed to “server-side” scripting run on the web server (e.g., PHP)
7. Javascript—mouse overs; edit tags and window pops up-javascript
8. More complicated need to use java.
9. Java is compiled to a bytecode (an intermediate stage) which is then run by a Java virtual machine (a software program)
10. Bytecode is downloaded with HTML file and interpreted by the browser
3. What’s the primary use of JavaScript? How are JavaScript programs generally made available to users?
1. Client-side scripting – written for webpages, interpreted by web browsers
2. There is downloadable scripts on the internet in which users can copy and add to their webpages
4. If a Web page seems to be more responsive than other Web pages, might it have something to do with the page being developed as an AJAX/Web 2.0 page? Or is that irrelevant to the responsiveness of the page?
1. Yes, AJAX used to make pages more responsive by changing small amounts of data, no reloading after changes
2. No need to reload entire Web page each time user makes a change
3. Not a technology in itself, but a term referring to use of a group of technologies together
1. What is the relationship between software and open source software (OSS)?
1. Source code available to everyone, unlike protect software code
2. What does the concept of “free” have to do with OSS?
1. Free – can manipulate all you want (like free speech)
3. You should understand the difference between software that is a free download (freeware), software that is closed (proprietary), shareware software, and OSS.
1. Open Source – can see source, chanagable, free and free, many contributors
2. Freeware – cannot see source, freely available, one person’s project
3. Shareware – cannot see source, trial-period/pay for it, one person’s project
4. Closed – cannot see source, need to pay, multiple people’s project
4. Can an operating system be open source? If so, name an example.
1. Yes, Linux – used in many data centers
5. Is it possible to make money with OSS?
1. Sell support & related services
2. Sell accessories
3. Sell books, T-shirts
4. Widget frosting
5. If you make and sell hardware, go open source with the software
6. Loss leader
7. Give away some software as a loss leader to draw attention to your other software
1. What is a database?
Repositories of structured business data.
2. What is dtabase purpose?
Contain large volumes of data that many people may access
3. What is a database management system? What are its components?
DBMS: Software that controls the creation, maintenance, and use of a database

Data dictionary: tells what fields, records and tables are in a database and their properties (e.g., data item name, whether it’s a date, number, etc)
Data definition language: for defining fields, records, tables and their relationships
Data manipulation language: for reading and changing what’s in a database (e.g., SQL)
Database utilities: for things like backing up the database, etc
Report generator: makes it easy to create reports from a database
4. What are the benefits of a relational DBMS?
Makes it easier to manage large amounts of data stored on magnetic disk
Supports one (or more) of the database types discussed earlier
Examples: Access (Microsoft), Oracle, DB2 (IBM), MySQL (Open source)
5. What is the benefit of a relational database over a flat file table? What types of problems are fixed by moving from a flat file structure to a relational structure? That is, understand the “anomalies” (related to data redundancy and dependencies).
Problems with flat file:
Insertions (adding new rows)what if don’t have all info

Updates (modifying existing rows)have to change every single one

Deletions (of a row)lose info

By using relational database:
Insertions, updates, and deletions no longer cause problems.
You can..
-Insert new stock even though no one owns it
-delete customer’s ownership of a stock and the customer and/or stock does not disappear
-change a customer’s address and you only have to change it in one place
-Facts are only stored once
6. Be able to identify all of the parts of a data table.
-row (record)
-primary key
7. Understand how relational tables “relate” to one another using keys.
8. What is the purpose of SQL?
The standard language for defining and manipulating data in a relational database. Structured Query Language (SQL) was created to shield the database programmer from understanding the specifics of how data is physically stored in each database management system and also to provide a universal foundation for updating, creating and extracting data from database systems that support an SQL interface.
9. Be able to read and interpret a basic SQL statement.
-select <columns>
- from <tables>
- where <logical condition>

*Simple SQL example:
-select price
- from stock
- where price > 80
10. Be able to describe the difference between natural and artificial keys. Also, be able to recognize the difference in an example.
A natural key (also called a logical or intelligent key) is a primary key that consists of a field, or a collection of fields, that is an inherent characteristic of the entity described by thte table and that is visible to users( example: ISBN, SSNhas to be unique. An artifical key=not a natural key b/c it’s not an inherent characteristic of a client. It’s a field that you add to a table to serve solely as the primary key and that is visible to users. I think the main way you can tell the difference is whether or not it is visible to other people. A SSN stays the same with you no matter what and can be seen by others (and have a meaning). For an artificial key, they just assign you one.. it can change and doesn’t mean anything or be seen by other people
11. In addition to retrieving data from a single table, what can you do with an Access query?
Make new reports, queries, tables containing different information form other databases. ??
12. Be able to read an Access query form and determine what information it would retrieve. Be clear about how and and or are implemented.
table 11
1. What is normalization? What’s the purpose?
-The process of ensuring that every field in a table depends on the key, the whole key, and nothing but the key
-Eliminates problems of insertion, update and deletion
-Results in a database where
-Facts are stored only once
-Easy to relate data in different tables
-Can ask ad hoc questions
2. Understand the meaning of “Every field depends on the key, the whole key, and nothing but the key.”
No Fields are dependent on fields other than the primary key
4. What’s the purpose of building an ER diagram?
It’s about organizing information
Things (i.e., entities)
These are important to us
We know facts about these things
Associations between things (i.e., relationships)
Facts we know about things (i.e., attributes)
• It turns out that the ER diagram …
~ Tells you what tables you need in your DB
~ Tells you what primary keys you need
~ Tells you what foreign keys are necessary
• It also helps document the DB
~ For you
~ For someone else
~ For possible changes that have to be made
5. What are the components of an ER diagram? Be able to describe each; be able to identify examples of each; be able to provide examples of each
- rectanglecollection of things that share common properties or characteristics
-attribute=named property or characteristic student number, name
-primary key
-composite key
-composite entry
-table 12
6. Be able to read the functional form of specifying table information—that is, customer(id, name, addr) or stock(symbol, currPrice, lastDiv).
write the table name followed by its fields in parentheses, underlingin the fields that represent the primary key and identifying the foreign keys for a table immediately after the table. Example: City (StateAbbrev, CityName, CityPopulation)
Foreign key: State Abrbrev to State table
7. What is a primary key? What is a composite key?
Primary key
1. Attribute that uniquely identifies each instance of an entity type
2. Denoted by underlining
Composite primary key
~ Identifier consisting of two (or more) attributes
8. Understand all of the guidelines for designing databases.
Steps to follow for designing databases:
-What are the entities?
-What are the relationships among the entities?
-1-1, 1-M, or M-N?
-Begin to draw the ER diagram in this step
-What should be the primary key for each entity?
-What are some important non-key attributes?
-Put them with the right entity (and the right primary key)
table 14
9. What is referential integrity? What’s the purpose? What does it have to do with foreign keys?
Foreign keys provide the mechanism for forming a relationship b/t two talbes, and referential integrity ensures that only valid relationships exist. Referential integrity is the constraint specifying that each nonnull foreign key value must match a primary key value in the lreated table. Which means that you cannot add a row with an unmatched foreign key value. Also means you can’t change or delete the related primary key value and leave the foreign key orphaned.
Use foreign keys to implement 1:M relationships; A foreign key is a primary key in one table and an attribute in another
10. What’s different about a composite entity? How does it differ from a normal M-M relationship?
A multiple-field primary key is a composite entity. (both keys are needed to uniquely identy each entity)
Composite primary key
~ Identifier consisting of two (or more) attributes

-Named property or characteristic of an entity of interest student number, name
A many-to-many relationship (M:N) exists b/t two tables when each row in the first table matches many rows in the second table and each row in the second table matches many rows in the first table. (you must use a third table to serve as ab ridge b/t the two many-to-many tables, the 3rd table has the primary keys of the many-to-many tables as its primary keys) (This is like when you use “state abbreviations” as the primary key. Thus, MI in one table will match many of the “MI” rows in the other tables and vice versa.
11. Understand the process of converting ER diagrams to tables. Be able to follow those steps.
12. Understand how to convert 1:M and M:M relationships to tables.
13. Be able to read a bubble diagram.
A way to graphically show what depends on what. (determinant=filed or a collection of fields, whose values determine the values of another field. ) This diagram is also called a data model diagram or a functional dependency diagram.
1. What are the seven components of a computer network? Be able to identify those components within a network.
1. Computer hardware: server, router, switch, hub (Router-get signal
Swith-has a lot of plugs) Switch-allows computers to talk to each other; router-gets the signal and computers can talk to outside world
2. Networking hardware: physical devices that control the flow of electromagnetic signals over network media
3. Media: “intervening substance through which something else is transmitted or carried on”
4. Communications software: programs that control the transfer of data over a network
5. Protocols: allowed and expected sequence of messages and their format
6. Providers: outside companies that own pieces of the network
7. Applications: why we care about networks
table 18
2. What’s the difference between a router and a switch? Which one creates a LAN? Which one connects networks?
1. Router: connects networks, moves packets (collection of bits)
2. Switch: connects computers and device to form a LAN
3. Hub: Allows devices to share the connection
3. Understand how latency and bandwidth can be used to describe the speed of communication media.
1. Latency – how fast a bit can go from point A to point B
2. Bandwidth – number of bits you can move fro A to B
4. What are a couple of examples of wired and wireless media? What’s the relative speed of these?
1. Wireless – WiFi, Bluetooth
2. Wired – Coaxial cable, optical fiber (fastest), twisted pairs (slowest)
5. What’s the difference between a LAN and a WAN?
1. Local area network – network of computers in single building
2. Wide area network – several buildings or cities (largest is the “internet”)
Circuit Switching : Used for
1. Phone calls
2. Leased lines for data communication
7. Characteristics
1. Continuous transmission
2. Dedicated circuit
3. The switch
8. Implications
1. Can be monitored
2. Can determine length of transmission
1. What is the difference between the Internet and the Web? Which one is “bigger”?
1. The Internet is a massive network of networks, a networking infrastructure.
The World Wide Web, or simply Web, is a way of accessing information over the medium of the Internet
2. What is HTTP used for?
Hypertext Transport Protocol - HTTP
1. for sharing documents over the Internet
3. What does an IP address look like? How does it relate to a URL?
1. 124.23324.23 – IP Address. A URL directs the browser to a certain IP Address
4. What’s a domain name?
1. Domain name is the text name corresponding to the numeric IP address of a computer on the Internet.