Flashcards
Revision cards for Computing iGCSE
Flashcards do conjunto (46)
- 1How many bits in a byte?8
- 2What does HTML stand for?Hypertext mark up language - a text based system for defining web pages
- 3What is Binary?A system of number using only two digits 0 and 1 (also called the base-2 system), unlike the decimal (or denary) system in everyday use that that uses ten (base-10)
- 4Why does data need protecting?Lots of personal/sensitive data.
Have confidence in companies holding data.
Protect against hackers. - 5What does ASCII stand for?American Standard Code for Information Interchange
- 6What is a Variable?Space for a single piece of data, each variable has a data type. You can change variables once they have been set.
- 7What is Boolean?A data type, can be either true or false and requires only one bit of storage.
- 8What is a String?A data type, stores any number of characters, such as a person's name, address and postcode.
- 9What is Malware?A piece of software that is hostile or intrusive. Examples are viruses, spyware, trojan horses and ad ware.
- 10What is Phishing?An attempt to gain personal information (name, address, credit card details...). Usually through email.
- 11What is RAM (Random Access Memory)?3 letters associated with volatile memory.
Generally any information stored with in this type of memory will be lost after the power is switched off. - 12What is Encryption?A method of scrambling data with a key code which makes data unintelligible.
- 13What is a Pixel?The smallest element of a bitmap image.
- 14What is an Algorithm?A sequence of unambiguous instructions to complete a task.
- 15What is Hardware?The physical components of a computer system.
- 16What is Software?The programs or instructions on a computer system.
- 17What is Data?numbers, characters or symbols that have no context or meaning.
- 18What is a LAN?Local Area Network. A network over a small geographical area.
- 19What is a Central Processing Unit (CPU)?Brain of the computer that performs instructions.
- 20What is an Input?Device used to input data into a computer system (e.g. keyboard, mouse, microphone, scanner, touch screen).
- 21What is an Output?Device that outputs information (such as sound, images, video, print outs) from a computer system to the user (e.g. monitor, printer, projector, speakers, printer).
- 22What is a PDF file?Portable document format - a file standard that displays a document accurately on any computer platform.
- 23What is a Program?A stored set of instructions for a computer to execute.
- 24Serial communicationBits are sent one signal at a time over a single wire .
- 25Parallel communicationSignals (bits) are sent simultaneously over a number of parallel wires.
- 26Simplex transmissionData travels in one direction only.
- 27Duplex transmissionData can travel in both directions simultaneously using two cables.
- 28Half-Duplex transmissionData can travel in both directions along a single cable, but not simultaneously.
- 29Bit rate and BaudThe speed of data is measured in bits per second (bps)
The Baud rate is the rate at which the signal changes
Baseband means one signal (bit) is sent at a time down a serial connection
In standard baseband, bit rate = baud rate. - 30BandwidthThe amount of data that can be carried at one time.
- 31Parity bitsA bit that is either 1 or 0 to make the digits odd or even depending on the request.
- 32Check digitA digit at the end of a string of numbers designed to check for mistakes in input or transmission.
- 33What does Modem stand for?Modulator/Demodulator.
- 34What is TCP (Transmission Control Protocol)?• Breaks up messages sent over the Internet into small chunks
called packets
• Reassembles the packets at the other end
• Detects errors
• Resends lost messages. - 35What is IP protocol?Routes the individual packets between sender and recipient.
- 36What is HTTP (hypertext transfer protocol)?It is used for
accessing and receiving web pages in the form of
HTML files on the Internet
• The protocol requests the web server to upload the
requested web page to the user’s browser for
viewing. - 37What is HTTPS (hypertext transfer secure protocol)?It encrypts the information so
that it cannot be hacked. - 38IP addressing• Every computer and other device connected to the
Internet has an IP address
• E.g. 81.101.137.12
• Packets are labelled with the
sender’s and the destination IP
addresses
• Packets are sent across the
Internet separately via different
routes and reassembled at the
end. - 39Network Interface Cards• Built into every networked device
• Wired or wireless. - 40MAC addressing• A Media Access Control (MAC) address is assigned to
each Network Interface Card (NIC) by the manufacturer
• Your computer may have more than one MAC address,
e.g. one for ethernet and one for wireless
• And a mobile phone may have two different MAC
addresses – one for wireless and one for bluetooth
• A MAC address looks like this:
3B:14:E6:39:0A:2C. - 41Parts of a web addresswww.abc.co.uk/images/logo.jpg
• Hosted on the WWW
• Name of the organisation
• A Company
• UK based
• Folder location and filename on the site - 42Domain Name System (DNS)• DNS technology allows you to type a name such as
google.co.uk into your web browser
• It translates the web address google.co.uk into an IP
address
• e.g. www.google.co.uk = 74.125.131.94. - 43DNS servers• There are 13 DNS “root” servers worldwide which
keep a complete database of all names and IP
addresses
• Other DNS servers lower down the hierarchy hold
parts of the database
• When a DNS server receives a request not in its
database, it will pass the request on to another
server until it reaches one with the matching name
and IP address
• Lower level DNS servers are owned by ISPs. - 44Cookies• A cookie is a small data file that a server will put on a
client computer
• Next time the client accesses the same server, the
cookie file will also be sent, identifying the client
• This would explain why:
• You get automatically logged in to a website
• You see online adverts relevant to you
and your recent searches
• Website preferences are saved - 45The client and the server• The client is a web browser such as Internet
Explorer, Chrome or Firefox
• The server is responsible for serving the web pages
depending on the client/end user requirement. - 46The role of a browserThe user types a web address (URL) into the
browser’s address bar
• The client (i.e. the web browser) forwards this
request to the server to access the web page
• The server acknowledges the request and sends the
HTML source code for the web page to the client
• The client receives the page source code and
renders it into a viewable web page.