Paper 1 Exam Questions

1 mark per bullet, max 2.  Extended ASCII uses more bits // ASCII uses fewer bits  Extended ASCII can represent more characters // ASCII can represent fewer characters  … by example (e.g. extended ASCII can represent European symbols / other languages)

 Height/amplitude of waveform is sampled/measured  Converted to / stored as binary/digital  Sample / measurements taken at a regular interval / set interval / by sensible example (eg 44,000 times per second)

 Image made of / split up into pixels  Each pixel given a binary code which represents the colour of that pixel  Each colour is given a different/unique binary code.  Metadata stored alongside the image

 Computers consist of transistors / switches / logic circuits / gates which only have two values / on or off / 1 or 0 / open or closed

Advantages  File size is reduced / gets smaller // image contains less data  ..so quicker to upload / download / load / transfer  …takes up less storage space // space on the web server  …less (mobile) data usage

Disadvantages  Quality of image is reduced (compared to original)  …because data is lost / removed // by example (eg fewer colours / lower resolution)  …reduction is permanent / not reversible

• sound file size = sample rate(Hz) x duration (it has to be in seconds) x bit depth • Analogue sounds must be stored in binary • image file size = colour depth x image height (px) x image width (px) • text file size = bits per character x number of characters

o Bit o Nibble (4 bits) o Byte (8 bits) o Kilobyte (1,000 bytes or 1 KB) o Megabyte (1,000 KB) o Gigabyte (1,000 MB) o Terabyte (1,000 GB) o Petabyte (1,000 TB)

 Check that the code is valid / real  Check it has been entered / sent / received correctly.  Makes it harder for people to make up discount codes

• Each character in character set has a unique binary number/value • Each character in the string is assigned its associated number/value • The binary value of each character is stored/combined (in order) • … by example e.g. The binary value for D, then for r, then for u • Uses ASCII/Extended ASCII/Unicode

• Easier/quicker to communicate / enter / write / read / remember • Less chance of input errors • They are shorter • Easy to convert between binary and Hexadecimal

5 a) • Number of pixels (in an image) OR • Height and width (of an image)

• 15* 6 = 90 (pixels in an image) • Multiply pixels x bits per pixel • …2 bits required per pixel because there are 3 colours • 180 bits overall answer

• Reduce number of pixels / resolution • Reduce number of colours • Use lossy compression • Use lossless compression

A switch performs a similar role to a hub and a bridge but is more powerful. It stores the MAC addresses of devices on a network and filters data packets to see which devices have asked for them. This makes a switch more efficient when demand is high. If, for example, a game involved lots of data being passed between machines, then a switch could reduce the amount of latency.

A network interface controller (NIC) provides a method of connecting to a network. A NIC offers an interface port for a wired connection. A wireless NIC provides a radio transceiver for connecting wirelessly.

When connected to a network each device is given a unique IP address. This address consists of four sets of up to three digits, each with a maximum value of 255, which are separated by dots. An example is: 192.168.0.254 When a node wants to send a message to another node, it uses the recipient node’s address as the destination. A switch on the network knows where the node with this address is and routes the message to it accordingly.

Transmission media carry data signals from one computer to another. Media are either wired or wireless. In modern networks, wired media use either twisted copper wiring, or fibre-optic cable. Each wired medium has differing characteristics

Wired connections are reliable and not usually subject to interference. However, they limit mobility - a wired device usually has to stay in place. Wireless connections use radio waves to carry signals. These signals are limited in range (usually up to 50 metres), but are subject to magnetic interference - they can also be blocked by walls. However, they are ideal for mobile devices as a device can connect to a network as long as it is in the range of a wireless access point.

Incremental:  Only the changes need to be backed up  The software/OS/settings are unlikely to have changed between backups  Small number of files likely to be used/edited between backups  Take less time to backup  Each backup will take less memory space to store Full:  Backup all the data/files and software  It might not take a significant time to back up entire system  He might only have a small number of files to be backed up each time  Faster to restore the backup  Needs to do a full before he can do an incremental

 Directs packets/data to destination // directs packets/data in a network  Receives packets/data from the network/Internet  Forwards packets/data to other computers on the network/Internet  Connects (different) networks together // e.g. joins home network to Internet  Has (public) IP address for LAN  Designates (private) IP addresses to network nodes

Inhabitants  Connection with the rest of the world  Access to more information  Up-to-date with news  E-commerce  Communication with people  Can be used in schools/for education  Cost (Devices and connection) Businesses  Sell products to wider audience//more customers  Purchase items from wider range/more places  Competitive prices  Tourism can be advertised  Online bookings for hotels Ethical issues  Access to inappropriate/illegal content  Lead to social pressure to be online and get technology  Cost  Introduces digital and social divide  Threats Privacy issues  Tracking of IPs/devices  Social media  Unwanted images and videos of people may be put online  Risk of threats e.g. phishing/pharming/virus

 The number of FDE cycles run per given time/second // the frequency that the clock ‘ticks’  3.8 billion cycles/instructions per second