SQA Higher Computing Science Flashcards

Terms and Definitions from the SQA Higher Computing Science course

Cardinality

The relationship 2 entities have between each other.

Each relationship also has a descriptor.

Dry run testing

Manually stepping through an algorithm without a computer.

Trace tables are an example of this.

Standard algorithm types

Find Max.

Find Min.

Linear Search.

Counting Occurrences.

Formal parameter

Information that has been passed into a function.

Actual Parameter

Information that is going to be passed into a module.

Advantages/disadvantages of using global variables

Often problematic. Errors in code can leave the value itself susceptible to accidental change.

Ways to manage traffic control

Adaptive traffic signals.

Intelligent routing systems.

Driverless cars.

Ways to manage a car management system

Intelligent smart stop systems.

Engine Control unit.

Breakpoint

A marker placed at a line of code in a program to halt execution at that point.

Can be placed where a programmer suspects there is a bug.

Disadvantages of using Bitmap Graphics

Have a very large file size as every pixel requires storage.

When scaled larger the picture will pixelate.

Bandwidth fault

Attacker send a large number of IP packets with the IP faked to take up all the available bandwidth.

Resource Starvation

Attacks aimed at taking up all of one resource (Memory, Disk Space)

Domain Name Service

An attack aiemd at taking down the DNS of a company.

Steps of the fetch execute cycle

1. Memory address of next instruction is placed on address bus

2. Processor activates Read Line on control bus

3. Instruction is fetched from memory location using data bus

4. Instruction decoded and executed

Factors affecting performance

Number of processors(cores)

Width of Data Bus

Clock Speed

Cache Memory

Main environmental impacts from computers

Heating Systems

Traffic Control

Car management system

Manage heating systems

Knowing when the house is empty

Smart Climate Assistant

Remote control of the heating system

Zoning areas of the house

_ & ?

A single character in an SQL wildcard

LIKE

Term in WHERE statement to enable an SQL wildcard

One to one relationship

Where two tables are linked together where a record in one table is only related to a single record in another table

One to many relationship

Most common type of relationship

A row in table A can have many matching rows in table B. But a row in table B can have only a matching row in table A.

Many to many relationship

Occurs when multiple records in a table are associated with multiple records in another table.

Entity Occurence Diagram

Aggregate functions

AVG()

COUNT()

MIN()

MAX()

SUM()

AVG()

Returns the average value of a numeric field

COUNT()

Returns the number of rows that match the criterias in the WHERE clause.

MIN()

Returns the lowest value of a field.

MAX()

Returns the largest value of a field

SUM()

Returns the total value of a numeric field?

Breakpoint

A marker placed at a line of code in a program to halt execution at that point.

Can be placed where the programmer suspects a bug.

Watchpoint

A way of targeting a specific variable to keep track of during program execution.

Record/class code

class A()

…def_init_(B):

……self.X=””

…….self.Y=0

…….selfZ=0.0

Local variable

Variable is declared inside a function.

Global variable

Variable declared outside of a function.

Advantages/disadvantages of using local variables

Improve maintainability by allowing developers to reuse variable names without conflict.

Purpose of a program

What the program is required to do, usually used to gain an overview of the entire system.

Scope of a program

Involves which deliverables will be created by the end of development.

Assumptions of a program

Beliefs based on previous experience and the information available to you. (Educated guesses)

Boundaries of a program

The limits that help to define what is in the project and what is not. It can also clarify any assumptions made by software developers regarding the request.

Advantages of modularity

Less code has to be written

Allows many people to work on the same program

Code can be stored across multiple files

Functions are short, simple and easy to understand

The same code can be used in many applications

Entity relationship diagram

AS

Word written in the SELECT statement to enable an aggregate function

A = [B]

Written in the WHERE statement to enable an aggregate function

Composite key

A primary key made up of two or more attributes.

Used when no single field is suitable for a primary key.

Compound key

Each attribute that makes up the key is a primary key in another table.

Junction table

Changes a many to many relationship to two one to many relationships instead.

Convert 2’s compliment to Binary

Write out number in standard Binary

Invert the digits

Add 1

Convert Binary to Denary

Invert the number

Add 1

Calculate denary and add a negative symbol

-2n^-1 to (2^n-1)-1

Formula for calculating the range of numbers

Range of Numbers

Do 2^ the number of bits

Divide in half = negative

Take 1 away = positive

Advantages and disadvantages of more bits being allocated to the Exponent

Increased Range

Decreased Accuracy/Precision

Advantages and disadvantages of more bits being allocated to the exponent

Increased Accuracy/Precision

Decreased Range

Processor’s effect on performance

More cores = higher performance because the processor execute more instructions at the same.

Clock speed’s effect on performance

Higher the speed, the faster the performance.

Software development methodologies

Iterative

Adaptive

Iterative development

Client is involved at the beginning and the end

Suitable for larger projects

Predictive

Adaptive development

Client is present at all major stages

Suitable for smaller projects

Effects on performance from width of the data bus

Larger the width the greater the performance as it can transfer more bits at once

Cache Memory’s effect on performance

Uses SRAM whereas RAM uses DRAM. If a computer has to the cache memory, from here the computer can access this instruction faster.

% & * in an SQL wildcard?

0, 1 or many characters.

Calculate the signbit and Mantissa 15 bits of a negative with a positive exponent

Sign Bit. Negative = 1 or Positive = 0

15 bits .Move number to the right of decimal points and fill the rest of the boxes with 0s

Exponent. How many moves to right? Calculate in 8 bit binary.

Unicode

Uses either 16/32 or 64 bits of storage meaning it can show far more characters.

Advantages of Bitmap Graphics

Can be edited at pixel level adding extra details to the image will not increase the file size

Can create photo realistic images

Tracking cookies

Records your details and transmits them back to the author

Used to gather marketing information

Public key

Encrypts the data

Private key

Decrypts the data

Computer Misuse Act actions

Access comptuer material without permission

Access computer material with the intent of commiting futher offences

Modify computer materials without permission

Symptoms and effects of DOS and DDOS attacks

Slow performance

Inability to acces

Disruption to users and business

Costs of DOS and DDOS attacks

Customers not being able to buy goods

Not being able to carry out the organisations business

Having to fix any faults

Reasons for DOS and DDOS attacks

Political

Personal

Reputation

Business

Money

Fetch execute cycle

A series of steps that takes place for a processor to execute an instruction.

Digital signature

Added to information to ensure that the information came from the coreect place.

Digital Certiciate information

The certificate serial number

The expiry date

The name of the holder

A copy of the public key

The digital signature of the certiciate authority.

% or Modulo in Python

Remainder operator

Advantages of modularity