Karteikarten
Computing revison flash cards
Karten in diesem Stapel (62)
- 1Kernel ExplainationManages system resources and maintains the communication between the hardware and software.
- 2Five Types of Operating SystemsMulti-User, Real-Time, Multi-Tasking, Distributed, Embedded
- 3Virtual Memory ExplanationVirtual memory is used when the RAM of your computer is filled, Virtual memory is temporary usage of hard drive data for RAM and is incredibly slow
- 4All 3 Sorting AlgorithmsBubble Sort, Insertion Sort & Quick Sort
- 5Two Types of Data StructureStatic & Dynamic
- 6Differences between the two data structuresMemory is allocated to the data dynamically in a dynamic structure whereas data is fixed and unchangeable at compile time with a static structure
- 73 Operations in a stackPop, Push, Top
- 8The functions of the 3 individual stack operationsPush - Adds an item to the top of the stack
Pop - Removes an item from the top of the stack
Top - Identifies the item at the top of the stack - 9Important parts of a stackFirst in stack,
Last in stack,
Stack pointer - 10Logic Gate: Both inputs A & BAND Gate
- 11Logic Gate: Either inputs A or B (Both still means ON)OR Gate
- 12Logic Gate: No inputsNOT Gate
- 13Logic Gate: A or B but not both are trueXOR Gate
- 14Logic Gate: Both A&B are false or trueXNOR Gate
- 15De Morgan's Law¬ (AVB) = ¬A ^ ¬B
- 16Distributive LawA (BVC) =ABVAC
- 17Simplify: A V B V AC V ABA V AC V AB V B (all a’s on one side)
A (1 V C V B) V B (use distributive law to factor out A)
A (1) V B (or anything by 1 returns 1)
A V B (AND anything by 1 returns itself)
Answer: A V B - 18Simplify: ¬AB V (A V B)¬AB V A V B (remove brackets)
B V ¬AB V A (commutative law to rearrange)
B (1 V ¬A) V A (factor out B)
B (1) V A (OR anything by 1 returns)
B V A (AND anything by 1 returns itself)
Answer: B V A - 19What is a Karnaugh Map?A condensed map like a truth table, used to work out inputs & outputs of Boolean algorithms
- 20Difference between lossless and lossy compression?Lossy compression is irreversible,
- 21What is a scheduler?A program that manages the amount of time different processes have in the CPU
- 22The Round Robin Scheduling AlgorithmAny open program is given an exact time to execute (quantum), the round robin consistently in a circle gives every other process the elapsed time to execute what it needs. Disadvantages in the way that it does not work in priorities.
- 23First Come First Served Scheduling AlgorithmA basic method where any new process is given execute time immediately until it is fully open
Can be much slower, but processes are always completed in their entirety. - 24Shortest Job First Scheduling AlgorithmA basic method where any process with a lower ‘wait time’ than the last is treated before others, this minimizes wait time.
- 25Shortest Time Remaining Scheduling AlgorithmSlight difference to the SJB method where instead this method executes any job closest to completion.
- 26Multi-level Feedback Queues Scheduling AlgorithmMultiple queues are made for the CPU to process and in each queue the instructions have different characteristics so the process are executed faster.
- 27What is polling?Polling is when the CPU keeps checking each peripheral/device to see if it needs attention.
- 28What is a interrupt service routine?At the end of each Fetch-decode-execute cycle, the processors check to see if there are any interrupts
If there are, and are a higher priority than the current task the following steps are carried out.
The contents of the program counter and other registers are copied to an area of memory called a stack
The relevant ISR can be loaded by changing the program counter to the value where the ISR starts in memory
When the ISR is complete, the previous values of the programs counter and other registers can be restored from the memory in the CPU - 29What is a device driver?OS are expected to communicate with a wide variety of drivers, each with different models and manufactures.
It would be impossible for makers of OS’s to program them to handle all existing and future devices, and this is why we have device drivers. - 30What is a virtual machine?A fully operational operating system which runs as a program instead of from the BIOS.
- 31The BIOSBasic Input/output System
When a computer first boots up it looks to the BIOS to get it up and running.
The BIOS checks if the computer is briefly functional, memory installed and accessible and the processor is working. This is called the Power-On self-test. - 32Open and closed source softwareClosed source is when the program (.exe) can be used but the actual source code is hidden from the user. Usually so that the code cannot be copied or stolen.
Open source software has its own source code visible and openly editable for changes and using. The code and company is usually copyrighted so it cannot be used again as the same code. - 33Octal ArithmeticOctal arithmetic is a lot like binary, except it works in powers of 8, meaning instead of a binary graph going 1,2,4,8,16... it would go 1,8,64,512...
- 34What is a database?A stored collection of information arranged in a logical, structured manner.
- 35What is a record?All of the data or information about one person or one thing.
- 36What is a flat file?All of your data is stored in one large table.
- 37Pros and Cons of a flat file?Pros:
• All records are stored in one place
• Easy to set up using a number of standard office applications
• Easy to understand
• Simple sorting of records can be carried out
• Record can be viewed or extracted on the basis of simple criteria
Cons:
• Potential duplication. As more and more records are added to the database it becomes difficult to avoid duplicate records. This is because there is no mechanism built in to the system to prevent duplication. Later you will see how ‘primary keys’ are used to prevent this.
• Non- unique records. Notice that Mr & Mrs Jones have identical ID’s This is because the person producing the database decided they may want to sort on identical telephone numbers and so has applied identical ID to the two records. This is fine for that purpose, but suppose you only wanted to extract Mrs Jones record. Now it is much more difficult
• Harder to update. Suppose that this flat file database also stored
• Inherently Inefficient. Consider a situation where the database now needs to hold an extra field to hold their email address. If there are tens of - 38Relational DatabaseHolds data over a number of tables instead of one. Records within the tables are linked (related) to records held in other tables.
- 393 Types of database keysPrimary Key, Secondary Key and Foreign Key
- 40Primary KeyIdentify the numbered record (A unique record)
Primary keys do not have to be numbers, they can be anything that makes each record unique - 41Secondary KeyIndexes the records according to title
Secondary keys can take up a lot of space in a database - 42Foreign KeyPoints to a record in another table whose primary key is the same value.
- 43What is an entity?An Entity is a person, place, thing or concept about which data can be collected. Examples include EMPLOYEE, HOUSE, and CAR.
- 44One to one relationshipsRelationships between two singular pieces of data
For example:
Husband & Wife - 45One to many relationshipsRelationships between a plural piece of data and a singular piece of data.
For example:
DiNitride and his content - 46Many to many relationshipsRelationships between two plural pieces of data
For example:
A School's Students and their pencils
(These are very very rare since they are so messy) - 47What is circuit switching in a network? An example?A physical pathway is established between sender and receiver for the duration of the data transfer.
The public telephone system is a good example of a switched network using circuit switched paths. - 48What is packet switching in a network? An example?The message transmitted is split into packets and these are routed through intermediary nodes (connectors).
A modern day PC & Router connection to the internet uses this type of switching - 49Pro and con of circuit switching?Pro:
All packets will arrive in the correct order.
Con:
Any break in the connection at all will fail the entire task. - 50Pro and con of packet switching?Pro:
Connection is resilient to failed links
Cons:
Packets don't arrive in order. This requires extra processing instead. - 51What is the internet?A collection of inter-connected networks
- 52What is the difference between the internet and the world wide web?The World Wide Web is the theoretical way of referencing the internet, as the internet is more the physical make-up of the connections.
- 53What does WAN & LAN stand for?Wide-Area-Connection & Local-Area-Connection
- 54What is a DNS and what does it do?A Domain-Name-System translates website addresses into IPv4 addresses so that the device being used to access the website can connect by address.
- 55What is an NIC and what does it do?A Network-Interface-card can be wired or wireless and acts as a connection to your router.
- 56What is a MAC address and what does it do?A Media-Access-Control address is a important unique address that is assigned to every different device with a connection of some sort to another device. It is used to tell apart two different devices while processing.
- 57Name all the parts of a TCP/IP stack (along with the layers)Application layer:
HTTP, FTP, HTTPS, Gopher
Transport layer:
TCP, UDP
Internet layer:
IP - 58What does HTML stand for and what is it?Hyper-Text-Markup-Language is a coding language specifically designed to be efficient in developing websites.
- 59What does SAP stand for and what is it?A Service-Access-Point is the point in which protocols will communicate with each other.
- 60During networking, what is 'Handshaking'?In order to set up a communication link both devices need to agree on a set of protocols to use. This must occur before a single byte of data is sent and is known as hand shaking
The handshaking signal is sent from one device to the other and is acknowledged by the second device. - 61JavaScript is a scripting language, what is a scripting language?An interpreted programming language that is designed to work within some run-time environments, rather than generating object code that can be run directly from the OS.
(Only understandable by certain devices) - 62Google sorts the website links on it's search engine by page rank, what is page rank?Basically, to ranks pages according to its external links.
If a page has a lot of links to it, then it is deemed more popular and therefor more significant.
They also look at the importance of the websites that links to the website, as that can also increase the ranking.
There are other issues like the dampening factor (probability of the user giving up clicking or continuing – generally around 0.85).