cambridge computer science as semester 1 finals

cambridge computer science as, mrs. preston

What does ASCII stand for?

American Standard Code for Information Interchange

The number of character that can be represented in ASCII-7 are

128

The number of character that can be represented in ASCII-8 are

256

What is the aim of Unicode?

Representing all characters with 1 system

Why does the correction factor of 0110 work in Binary Coded Decimals?

The correction factor 6 is used because a nibble can represent up to 15, yet a BCD can only express up to 9. The 6 carries it to the next nibble.

What are integers?

non-decimal numbers

What are signed integers?

integers with signs (e.g. -1)

What are unsigned integers?

integers without signs (e.g. 1)

Given the following decimal prefix, state its abbreviation and value: kilo

k, 10³

Given the following decimal prefix, state its abbreviation and value: mega

M, 10^6

Given the following decimal prefix, state its abbreviation and value: giga

G, 10^9

Given the following decimal prefix, state its abbreviation and value: tera

T, 10^12

Given the following binary prefix, state its abbreviation and value: kibi

Ki, 2^10

Given the following binary prefix, state its abbreviation and value: mebi

Mi, 2^20

Given the following binary prefix, state its abbreviation and value: gibi

Gi, 2^30

Given the following binary prefix, state its abbreviation and value: tebi

Ti, 2^40

What is One’s Complement?

a binary obtained by subtracting each binary digit from 1

What is Two’s Complement?

a binary obtained by adding 1 to One’s Complement

What is overflow?

a condition when the result is larger than capacity

What is BCD?

Binary Coded Decimal

What is a vector graphic?

a graphic consisting of drawing objects defined in a drawing list

What are examples of attributes for objects’ properties?

center and radius (of a circle), thickness, line style, line color, color that fills shape

What is a drawing object?

a component defined by geometric formulae and associated properties

What is a drawing list?

contains 1 set of values for each drawing object

What is a property?

defines 1 aspect of appearance of drawing object

What is an important property?

dimensions of objects are not defined explicitly, but are defined relative to images canvas

What are bitmaps?

2D array of pixels

What is a pixel?

smallest identifiable component of bitmap, has position in matrix and color

What is color depth?

number bits per pixel

What is bit depth?

number of bits used to store red, green, and blue in RGB scheme

What is resolution?

product of number of pixels per row and column

What is image resolution?

defined in bitmap file

What is screen resolution?

ability of device showing image

What is a file header?

contains information on how graphic was constructed

Vector graphic versus Bitmap:

a. _____ is chosen if a diagram is needed to be constructed for part of an architectural, engineering, manufacturing design.

Vector graphic

Vector graphic versus Bitmap:

b. Printing the image on laser or inkjet printer a _____ should be used.

bitmap

Vector graphic versus Bitmap:

c. Digital camera produce _____ images.

bitmap

Vector graphic versus Bitmap:

d. _____ is first choice for insertion of an image into document, publication, or web page.

Bitmap

Vector graphic versus Bitmap:

e. Generally images are stored as _____.

bitmaps

Vector graphic versus Bitmap:

f. _____ is scalable.

Vector graphic

Vector graphic versus Bitmap:

g. A _____ files contains a drawing list with commands for each object included in the image.

vector graphic

Sound consists of a large number of _____, each with a defined _____.

waves, frequency

Storing sound requires converting the _____ sound signal to _____.

analog, digital

Two factors that determine the quality of the sound recording are _____ and _____.

sampling rate, sampling resolution

Define sampling resolution

number of bits used to store each value

Define sampling rate

number of samples taken per second

Define analog data

data obtained physically with values within continuous range

Define digital data

data stored as binary values from discrete range

Define sampling

taking measurements at regular intervals and storing them

List two types of compression

lossy and lossless

Since all data is binary, which type of compression can be used for all files?

lossless

Which compression has specialized applications developed for particular file types?

lossy

Text files require which type of compression?

lossless

Give one example where lossy compression will be useful.

Lossy compression is useful to use less storage for a file

Give one example where lossless compression will be useful.

Lossless compression is needed for text files because no information can be lost.

What is a WAN?

Wide Area Network, a system of networks across a large area.

List three benefits of having a WAN

1. A “job” could be run on a remote computer that had the required application software.

2. A data archive that was stored on a remote computer could be accessed.

3. A message could be transmitted electronically to a user on a remote computer.

List five characteristics of a WAN

1. It will be used by organization or company to connect sites or branches.

2. It will not be owned by the organization or company.

3. It will be leased from a PSTN.

4. A dedicated link will be provided by the PTSN.

5. Transmission within the WAN will be switch to switch.

Define end systems

either a user workstation or server

Define server

a system providing a service to end systems

What is a LAN?

Local Area Network, a system of networks in a small area

List five benefits of having a LAN

1. save expenses of installing application software by attaching to LAN

2. file server attach to LAN to store larger files and allow file sharing

3. 1 or more printers attached to print server connected to LAN

4. use electronic mail to communicate

5. “paper-less office”

List five characteristics of a LAN

1. used by organization or site within site or branch

2. owned by organization or computer

3. one of many LANs

4. transmission medium is twisted pair cable or WiFi

5. contain device allowing connection to other networks

Describe the two options for client-server model are

1. thin-client: client only provides input

2. thick-client: client involved in some processing

Describe three approaches when it is appropriate to use client-server architecture

1. server stores databases

2. server stores web applications for information

3. server stores web applications for e-commerce and financial transaction

Describe peer-to-peer network file sharing

peers act as clients to seek files

Describe peer-to-peer file network file sharing advantages over client-server downloading

1. avoids network congestion

2. parts of file downloaded separately

3. parts available from multiple hosts

Describe client-server file network file sharing advantages

1. organizations control download and usage of files

2. better protected from malware

Five requirements for a data communication systems

a. sender

b. receiver

c. transmission medium

d. message

e. protocol

Define simplex mode

one-way data flow

Define half duplex mode

data flow in either direction, but not simultaneous

Define full duplex

data flow in both ways

Define broadcast message

one-to-all communication

Define multicast message

one-to-many communication

Define unicast message

one-to-one communication

A bus topology has _____ link but it is shared by a number of _____.

1, end systems

Therefore, a bus topology is described as a _____-point connection.

multi

In a bus topology, _____ messages are _____ even if intended for one end-system.

all, broadcast

A bus topology is _____ because a fault in one end-system or in the link to it _____ effect the use of the network.

resilient, does not

A mesh topology each _____ has a point-to-point connection to each of the other end systems.

end system

In a mesh topology, transmission is _____.

duplex

In a mesh topology, messages can be sent in 3 ways: _____, _____, and _____.

unicast, multicast, broadcast

A mesh topology may be unrealistic due to?

amount of cabling needed

A mesh topology can be used when individual _____ switches are _____in a network.

LAN, connected

A mesh topology is essential for the _____ of _____ within the infrastructure of the internet.

connect, routers

What is a router?

device that acts as a node

In a star topology each end system has a _____-to-_____ connection to a _____ device.

point, point, central

In a star topology, transmission is _____.

duplex

In a star topology, messages can be sent in 3 ways: _____, _____, and _____.

unicast, multicast, broadcast

In a star topology, failure of an end system or its link leaves other end systems _____.

unaffected

In a star topology, the _____ device must not fail.

central

In a bus topology most end systems might be user _____ and other are _____.

workstations, servers

In a star topology, the end systems might be workstations or servers, but the central device is _____.

different

In a star topology, the central device is a specialized device with the purpose of _____ other devices in the network.

connecting

Currently, a star topology is the _____ way to configure a network.

usual

Main reason for star topology is the central device can be used to connect to other _____ such as the _____.

networks, Internet

Define hybrid networks.

a collection of connected LANs where some have different topologies and technologies

Define cable

transmission using copper wire or fiber optic

Define bandwidth

measure of amount of data transmitted per system

Which topology does the image represent?

star topology