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Details

OCR Computer Science
Revision for GCSE Mock exam
30
Computer Science
Not Applicable
11/20/2013

Additional Computer Science Flashcards

 


 

Cards

Term

add the following bytes

 

11011000

01100000

__________

 

__________

Definition

Your answer should be one of the following

 

00011000

 

 (1)00111000

 

(1)00001100

 

Term
State the problem that will occure if a computer is to store the result as a byte ?
Definition
There is a carry left over after the addition and this will not fit into one byte
Term

what are the following file types used for

  1. HTML
  2. JPG
  3. MP3
  4. PDF
Definition
  1. HTML: Language used to create webpage content
  2. jpg: images/photos
  3. mp3: sound/sudio/music files
  4. pdf: documents
Term
{image:|}
Definition
1
Term
[image]
Definition
0
Term
[image]
Definition
[image]
Term

Most Computer systems use at least one storage device,

 

Explain one reason why a secondary storage device is needed in most computer systems

Definition
  • To store the files/eg operating system

Even when the system is switched off/which must be non-volatile.

ROM will store stystem data even when the system is switched off this is known as secondary storage devices

 

Term
  1. Some secondary storage devices are magnetic and others are solid state. Describe the characteristics of magnetic and solid state secondary storage.
Definition

Magnetic.

  • Normally large and very cheap
  • Used as main storage in most computers
  • has moving parts so no good when moving about

Solid State

 . Expensive

. no moving parts so easy to move about

. replaces floppy disks etc

 

Term

A school haS all of its computers in a local area network (LAN)

 

State two benefits of a LAN

 

 

Definition
  • Can share files/many people can work on the  on same files at the same time
  • Can share hardware resources i.e. a printer
  • Can access their files from any computer/classroom
  • Can work together from different computers using instant messaging
  • Centralised deployment of software to all computers

 

Term
Explain two measures which the school will need to take to ensure the security of the network
Definition
  • Passwords to protect user accounts
  • Network restrictions
  • firewalls to prevent unatuorised access / hacking into the network
Term

When recording a sound file on a computer, the sound needs to be sampled...

 

Describe how sampling is used when storing sound

Definition
  • The height/amplitutde of the sound wave is measured at regular intervals
  • sound is converted to binary
Term
Explain the effect of the sampling interval on the size and quality of the sound file recording
Definition
  • If the interval is smaller / you do not get the full effect of the sound and the quality is not so good

 

  • If you make your sample bigger the file is larger but the sound is far bettr and closer to the original
Term
  • The accedent and emergency department of a hospital uses a computer systme to decide what order in which patients are treated

 

Describe advantages of using a computer system instead of a person to decide the order, also describe why this system needs to be reliable

Definition
  • Computers are more stematic than human and will give more consistent results
  • Software can be deployed in several departments
  • easier to analyse records

reliability

  • Critical application, lives may be at stake if the system crashes
  • loss of data or power is a bad thing
Term
Explain why data is stored in computers in binary format
Definition

Computers have lots of electrical circuits tht have two states

either off or on i.e. 1/0

Term

In the ASCII character set, the character codes for the first three capital letters are shown as

 

  • A - 01000001
  • B - 01000010
  • C - 01000011

State how the ASCII character set is used to represent text in computer

Definition

Each character is assigned a unique character code which is a binary number

Term

Convert the word CAB into binary using ASCII character set

Definition

 

010000110100000101000010

Term
Explain why the ASCII character set is not suitable for representing text in all languages of the world
Definition

ASCII uses 8 bits...

 

... and so can only represent 255/256 distinct characters...

 

..many more characters are needed for coping with all languages

 

 

 

ASCII does contain characters used in some languages

 

Term

Charley is writing a program for music students. To make sure that there are no logic erros in the program, Charey uses a test plan

 

  • Describe what is meant by a logic error
Definition

The error does not prevent program running…


 

But it does not produce the expected output/it does not do what the programmer expected

 

 

 

 

Term

The program uses the letters in the following list to represent musical notes

CDEFGAB

When the user inputs a letter from this list, the program outpus the next three notes in the list. If it gets to the end of the list, it starts again from the beginning, so the next note after B is C.

Complete a test plan by stating, for each input data, the expected outcome and reason for test.

 

C      expected outcome      reason for test

A      expected outcome      reason for test

H      expected outcome      reason for test

Definition

C     DEF      Checks the output is the next three letters in the list

A     BCD      Checks the output goes back to the beginning of the list

 

H     Error message     Not a valid/ exising note

Term

A User buys a new computer with an operating system and some utilities

 

State two functions of the operating system

Definition
  • Provides interfaces between user and comupter
  • Provides a platform for software to run
  • manages peripherals used by the system like printers, mouse, keyboard
  • manages memory
Term

In the table are some utilities

are the disk or security utilities

 

used for security      Disk

 

Antivirus 

Defragmenter

File Transfer

Firewall

Definition

 

 

Antivirus      used for security

Defragmenter disk

file transfer     disk

firewall    used for security

Term

Some of the softwre in His computer is open source

 

Describe what is meant by open source software

Definition
  • The source code can be distributed
  • the customer can modify the code
  • the customer can redistribute (swap) the code
Term
Describe what is meant by a database
Definition

A structured organised store of data

data can be queried

Term
  • When a person jones a website, they need to enter some personal data which is validated using rules. Fore example, the date of birth must be in the past

 

state one rule for each

Email address

Gender

Password

Definition

Email address

Must contain an @ sign

Must contain a full stop after the @ sign

 

Gender

Must be Male Female or Other

Password

Must have a given minimum length

Must contain a non-letter

Term

Each user can upload several pictures. Each picture has a date and comment.

The personal data of users is stored in a table called USER the data about the pictures is stored in a separte table called PICTURE

 

Explain why the data about the pictures should be in a seperate table. and how the tables can be linked

Definition
  • Avoids data repetition of the personal details of the user
  • A user can have more than one picture
  • The primary key of the USER is stored in the PICTURE table where it is called a foreign key
Term

Jim is writing a prgram to calculate the wages of workers in a factory

Jim uses an Integrated Development Environment (IDE) to create the program

Describe two tools in an IDE that can help him when creating the program

Definition
  • Colour coding keywords
  • Auto completes code as you type
  • debugging tools
  • highlights errors in the code

 

Term

Workers sometimes get a £50 bonus

here is the algorithm used to calulate whether a worker should get a bonus

 

Limit = 200

INPUT WagesEarned

IF WagesEarned < Limit THEN

     Pay = WagesEarned

Else

     Pay = WagesEarned + 50

END IF

 

State the value of pay after this code is run for each of the follwing

 

WagesEarned = 50    Pay = _____________

WagesEarned = 200  Pay = ____________

Definition

50

 

 

250

Term

The wages earned by a worker is either £2 for every teddy bear they have made or £5 for every hour they have worked which ever is larger.

 

Write an algorithm that:

  • allows the user to input the number of teddy bears made and the number of hours worked
  • calculates the wages for the number of teddy bears made
  • calculates the wages for the number of hours worked
  • outputs the larger of the two results
Definition

INPUT TeddyBears

 

INPUT Hours

 

PerTeddyBear = 2 * TeddyBears

 

PerHour = 5 * Hours

 

IF PerTeddyBear > PerHour THEN

 

    OUTPUT PerTeddyBear

 

ELSE

 

    OUTPUT PerHour

END IF

 

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