Year 10 Half Term 1: Von Neumann Architecture 1.1.1
Von Neumann architecture
Program instructions and the data the programs are using are both stored in the same memory
The CPU accesses both instructions and data from the �same RAM
A visual diagram of the CPU
Instructions and data are stored in the same RAM
A Bus (group of electrical wires) is used to fetch data for the CPU to execute
Glossary:
CPU
Central Processing Unit. -The “brain” of the computer
CU Control Unit. -Part of the CPU that manages the functions of all other parts of the CPU
RAM Random Access Memory -The main volatile memory into which programs are loaded from the hard drive
MAR Memory Address Register -Small fast memory used to store the RAM address of the next instruction
MDR Memory Data Register -Small, fast memory used to store the information collected from the RAM before processing
PC Program Counter -Keepstrack of the current instruction number of the program
Accumulator Small, fast memory, usedto keep track of the data currently being processed
ALU Arithmetic and Logic Unit -Does the basic mathematics and comparisons during processing
Bridge (North / South) Junctions on a motherboard where the bus connections are controlled and routed. Northbridge deals with core functions, whilst the Southbridge deals with the peripherals, input and output devices and Secondary Storage.
von Neumann Architecture The method used by all modern computers to allow the programming of a machine to be changed depending on the required function.
Fetch / Decode/Execute Cycle Basisof the von Neumann architecture –the repeated process where instructions are fetched from RAM, decoded into tasks and data, then carried out.
Year 10 Half Term 1: Von Neumann Architecture 1.1.1
Glossary:
CPU
Central Processing Unit. -The “brain” of the computer
CU Control Unit. -Part of the CPU that manages the functions of all other parts of the CPU
RAM Random Access Memory -The main volatile memory into which programs are loaded from the hard drive
MAR Memory Address Register -Small fast memory used to store the RAM address of the next instruction
MDR Memory Data Register -Small, fast memory used to store the information collected from the RAM before processing
PC Program Counter -Keepstrack of the current instruction number of the program
Accumulator Small, fast memory, usedto keep track of the data currently being processed
ALU Arithmetic and Logic Unit -Does the basic mathematics and comparisons during processing
Bridge (North / South) Junctions on a motherboard where the bus connections are controlled and routed. Northbridge deals with core functions, whilst the Southbridge deals with the peripherals, input and output devices and Secondary Storage.
von Neumann Architecture The method used by all modern computers to allow the programming of a machine to be changed depending on the required function.
Fetch / Decode/Execute Cycle Basisof the von Neumann architecture –the repeated process where instructions are fetched from RAM, decoded into tasks and data, then carried out.
The accumulator (ACC) is where arithmetic and logic results are temporarily stored, much like the M+ function on �a calculator
Central processing unit
Year 10 Half Term 1: Von Neumann Architecture 1.1.1
Glossary:
Machine Code A program, stored in binary, that the CPU undertakes the FDE cycle on. All programs must be in machine code to work
Instruction A single line of machine code, containing the command and data location on which it is to be executed. Stored in binary
Opcode The first part of the instruction, is the command
Operand The second part of the instruction is the data on which to carry out the command. This may be actual data stored in binary form, or a memory location reference of where to find the data
Year 10 Half Term 1: Von Neumann Architecture 1.1.2
What affects CPU performance?
Glossary:
Clock Speed The number of FDE cycles that a CPU can carry out per second. Measured in Ghz
(1 Ghz= 109cycles per second or 1,000,000,000hz)
Cores Some processors have multiple CPUs which can work in parallel, sequentially or can multitask. Dual and Quad cores are common in modern PCs
Cache Incredibly fast, but very expensive volatile memory using in the CPU
The faster the clock speed, the faster the instructions are processed
The data used most often by the CPU is held in �Level 1 cache so is available extremely quickly
In most systems, Level 1 cache is used
1 GHz processor is performing one billion cycles per second.
A quad-core processor working on many different tasks simultaneously, under ideal conditions can be up to four times faster than a single-core processor
Year 10 Half Term 1: Von Neumann Architecture 1.1.3
Glossary:
Embedded systems
A single microprocessor that includes RAM, ROM and a CPU
An embedded system is a computer system that is designed for a specific function using simple inputs, in contrast to a general-purpose computer that can carry out many tasks
Without embedded systems, a digital device would not be able to perform specific functions
For example, a dishwasher wouldn’t know when to heat the water, or a satnav wouldn’t know how to communicate with a satellite
Some examples of embedded systems in �cars
Year 10 Half Term 2: Primary memory 1.2.1
Glossary:
Volatile Memory which requires constant electrical charge. If the power is turned off, then the data is lost
Non-volatile Memory which can retain its data when the power is turned off
RAM (Random Access Memory)
ROM Read-Only Memory
Cache Very fast memory, on, or very close to the CPU
Virtual Memory A section of the HDD which can be used as RAM for very memory intensive processes
Flash Memory
A type of dynamic (changeable) ROM
Boot Process
The instructions needed to start the computer and to initialize the operating system.
POST Power On Startup Test
A series of checks done on the hardware of the computer to ensure the machine can run.
Two types of memory used in computers are:
RAM
ROM
Types of memory
memory, which stores data in a single transistor and capacitor. This means it needs a constantly recycled charge to hold its data. If the power is turned off, it cannot refresh the data and it is lost. This is known as DYNAMIC Memory
The data is hardcoded onto the chip by the manufacturer, and cannot be overwritten by the user. Because it holds its information even when the power is turned off, this makes ROM ideal for storing the instructions needed to get the computer started up –the BOOT PROCESS, and POST.
To increase the speed and efficiency of RAM, most machines allocate a small portion of the Hard Disk to VIRTUAL MEMORY. The contents of the RAM are moved between the slower Virtual Memory and RAM as and when they are needed.
Virtual Memory
Advantages
Uses cheap secondary storage on the hard drive
Prevents error messages saying ‘out of memory’ – the programs and files will still open
Disadvantages
Accessing virtual memory is very slow
To access data, the existing data in RAM needs to be copied to the virtual memory, then data in virtual memory needs to be copied to RAM
Year 10 Half Term 2: Searching and sorting algorithms 2.1.3
Glossary:
Algorithm
An abstracted program which completes a given task, whatever the data provided
Search Searching is looking through data, making comparisons with a search term, until the algorithm either finds the data, or identifies that it is not present.
Linear Search A type of search where the computer checks every variable, in order, until it finds the search term. Potentially very slow.
Binary Search A search type based on repeatedly halving the searchable data, until the search term is found
Binary search (list has to already be sorted in order )
Linear search (can be used even when list is not in order)
Glossary:
Sort- Putting given sets of data into specified order –usually ascending (alphabetical) or descending (reverse alphabetical
Bubble Sort-A method of sorting data which looks at pairs of variable, and swaps them around if out of order. This continues until there are no more swaps to be made
Merge Sort-Splits the data into increasingly small segments, until single data points are reached, then reassembles the data structure one item at a time.
Insertion Sort-Checks through the data until finding the first incorrectly places item. The algorithm then checks all the previous places to see where the data fits, before inserting it into this slot.
Year 10 Half Term 2: Searching and sorting algorithms 2.1.3
Bubble sort
Insertion sort
Merge sort
Year 10 Half Term 2: binary addition & shift 1.2.4
Glossary:
Overflow error- Where the denary value cannot be represented with the given number of bits.
Binary Shift -The method for multiplying and dividing numbers in binary. Is not necessarily mathematically correct
Most Significant Bit The left-most bit in a binary number –it has the highest value
Least Significant Bit The right-most bit in a binary number –it has the lowest possible value = 0 or 1
Check digit- An additional digit at the end of a string of numbers used to
check for mistakes in transmission. ISBNs are formed of 12 bits
for the item number, then the 13th is a check digit.
The largest number 8 bits can represent is 255. if adding two binary numbers that total more than 255 then a 9th bit will be required
Computers store things in a finite amount of space in memory. If the total goes over this amount of space then an overflow error will occur
Adding in binary
Over flow error-
Adding in denary
77896
+ 123
78019
11
Carried bit
A 9th bit is required to represent this addition. If it doesn't fit an overflow error occurs
11111100
00001111+
100001011
Binary shift
To multiply a binary number | Shift to the left |
15 If we shift 2 place to the left we get (i.e multiply by 4.) 60 | |
To divide a binary number | Shift to the right |
112 If we shift three places to the right we get (i.e divide by 8) 14 | |
0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 |
0 | 0 | 1 | 1 | 1 | 1 | 0 | 0 |
0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 |
111000101
Least Significant Bit
Most Significant Bit
Year 10 Half Term 3: Programming techniques 2.2.1
Glossary:
Variable- A piece of stored data, used in a computer program, which can be changed or altered by the program
Constant- A piece of stored data which cannot be changed by the program or user
Operator An operator is a mathematical symbol, used to work with data in a program
Input - Data, entered into a program, by the user
Output - The returned result of an algorithm
Algorithm -A set of instructions to carry out a process or problem-solving operation, especially by a computer
Iteration- Code is repeated (looped), either while something is true
or for a number of times
Count controlled loop- - A type of LOOP which repeats a series of steps with a finite number of variable changes
Condition controlled loop - A type of loop which repeats until a condition is met.
.
Sequence- A series of coded instructions for a computer to follow, step by step
Selection - Selects a pathways through the code based on whether a
condition is true
Variable.write -File.write(“VariableName”)
open - Open a text file
List - MyList = [“Apple”,”Fruit”,”Bannana”,”Parsnip”]
Nested selection statements – if statements within another if statement
SELECTION
ITERATION
SEQUENCE
Random integer
Random integer | Import random random.randint(0,9) |
choice | random.choice(‘a’,’b’,’c’) |
Random value between two integers | random.random() |
Nested IF statement
switch menuChoice:
case "1":
print("You selected 1")
case "2":
print("You selected 2")
case "3":
print("You selected 3")
default:
print("This is not a valid choice")
endswitch
Switch/case statement
This statement may be used when a selection is to be made from several alternatives, for example when choosing from a menu
Year 10 Half Term 3: Programming techniques 2.2.1
Glossary:
Variable- A piece of stored data, used in a computer program, which can be changed or altered by the program
Constant- A piece of stored data which cannot be changed by the program or user
Operator An operator is a mathematical symbol, used to work with data in a program
Input - Data, entered into a program, by the user
Output - The returned result of an algorithm
Algorithm -A set of instructions to carry out a process or problem-solving operation, especially by a computer
Iteration- Code is repeated (looped), either while something is true
or for a number of times
Count controlled loop- - A type of LOOP which repeats a series of steps with a finite number of variable changes
Condition controlled loop - A type of loop which repeats until a condition is met.
.
Sequence- A series of coded instructions for a computer to follow, step by step
Selection - Selects a pathways through the code based on whether a
condition is true
Variable.write -File.write(“VariableName”)
open - Open a text file
List - MyList = [“Apple”,”Fruit”,”Bannana”,”Parsnip”]
Mark1 | Mark2 | Condition | True or False? |
80 | 67 | (mark1 >= 80) AND (mark2 >= 80) | False |
82 | 80 | (mark1 >= 80) OR (mark2 >= 80) | True |
35 | | (mark1 > 30) OR (mark1 < 50) | True |
65 | | (mark1 < 30) OR (mark1 > 80) | False |
0 | 75 | NOT(mark1 > 50) AND (mark2 > 50) | True |
65 | 85 | NOT(mark1 < 60) AND NOT (mark2 < 80) | True |
Boolean operators
Boolean expressions can include the Boolean operators AND, OR and NOT
Examples of usage in Boolean expressions
Concatenation
Year 10 Half Term 3: Programming techniques 2.2.1
use a nested FOR loop to print out a grid | for i in range (10): for i in range (10): print ("x ",end="") print()
|
Use a nested while and if to print out only even numbers | i=0 while i<51: if (i%2==0): print(i) i=i+1 |
Create a list | shapes=["square","circle"] |
Access element by index pos | shapes[1] -> circle |
Append item to list | shapes.append(“triangle”) |
Remove item from list | shapes.remove(“circle”) |
Remove item from list by index | shapes.pop(1) |
Insert item into list | shapes.insert(2,”rectangle”) |
Number of elements in a list | len(shapes) |
Get index pos of item in list | shapes.index(“triangle”) |
Concatenating lists | shapesGroup1[“square”,”circle”] shapesGroup2=[“triangle”] shapes=shapesGroup1+shapesGroup2 |
Loop through list
| for i in range(len(shapes)): print(shapes[i]) |
Reverse elements in a list | shapes.reverse() |
Order elements in a list | shapes.sort() |
Create a 2D list
| d = [ [23, 14, 17], [12, 18, 37], [16, 67, 83]]
|
Another way to create a 2D list | a = [23, 14, 17] b = [12, 18, 37] c = [16, 67, 83] d = [a,b,c]
|
Access element by index position | d[1][2] -> 37 |
Get length of a string | len(“Hello”) | LEN(“Hello”) |
Character to character code | ord("a") -> 97 | ORD("a") |
Character code to character | chr(101) -> ‘e’ | CHR(101) |
String to integer | a=int(“12”) | a=INT(“12”) |
String to float | a=float(“12.3”) | a=FLOAT(“12.3”) |
integer to string | a=str(12) | a=STR(12) |
real to string | a=str(12.3) | a=STR(12.3) |
Concatenation -merge multiple strings together
| a=“hello ” b=“world” c=a+b print(c) -> hello world
|
Return the position of a character If there is more than 1 of the same character the position of the first character is returned.
| student = “Hermione" student.index(‘i')
|
Find the character at a specified position | student = “Hermione" print(student[2]) -> r |
Nested structures
Strings
2D lists
Lists
Year 10 Half Term 3: Programming techniques 2.2.1
Example | student=“Harry Potter” |
|
Output the first two characters | print(student[0:2]) | Ha |
Output the first three characters | print(student[:3]) | Har |
Output characters 2-4 | print(student[2:5]) | Rry |
Output the last 3 characters | print(student[-3:]) | Ter |
Output a middle set of characters | print(student[4:-3])
| y Pot |
Procedure: No input parameters or return | SUB greeting() OUTPUT “hello” ENDSUB
| def greeting(): print(“hello”)
call: greeting()
|
Procedure: One input parameter, no return | SUB greeting(name) OUTPUT “Hello”,name ENDSUB | def greeting(name): print(“Hello",name)
greeting(“grey”) |
Function: 1 input parameter, and 1 return value | SUB add(n) a ← 0 FOR a ← 0 TO n a ← a + n ENDFOR RETURN a ENDSUB | def add(n): a=0 for a in range(n+1): a=a+n return a
|
Function: Two input parameters, and 1 return value | SUB (num1,num2) sum=num1+num2 return sum
| def add(num1,num2): sum=num1+num2 return sum
greeting(1,2) |
Subroutines are a way of managing and organising programs in a structured way. This allows us to break up programs into smaller chunks.
Functions are subroutines that have both input and output
The scope of a variable determines which parts of a program can access and use that variable.
A local variable is a variable that can only be accessed within a certain block of code typically within a function. Local variables are not recognized outside a function unless they are returned. There is no way of modifying or changing the behaviour of a local variable outside its scope.
Global variables need to defined throughout the running of the whole program. This is an inefficient use of memory resources. Local variables are defined only when they are needed an so have less demand on memory. Local variables only exist within the subroutine.
Sub Strings manipulation
Subroutines functions/procedures
Variables scope
Year 10 Half Term 3: additional Programming techniques 2.2.3
Glossary:
Variable- A piece of stored data, used in a computer program, which can be changed or altered by the program
Constant- A piece of stored data which cannot be changed by the program or user
Operator An operator is a mathematical symbol, used to work with data in a program
Input - Data, entered into a program, by the user
Output - The returned result of an algorithm
Algorithm -A set of instructions to carry out a process or problem-solving operation, especially by a computer
Iteration- Code is repeated (looped), either while something is true
or for a number of times
Count controlled loop- - A type of LOOP which repeats a series of steps with a finite number of variable changes
Open file- an instruction to open an external file into a program
Read file- an instruction to read the opened file
Variable scope- the reach of the variable within a program
List slicing-
Open file Whatever we are doing to a file whether we are reading, writing or adding to or modifying a file we first need to open it using:
Open (filename,access_mode)
There are a range of access mode depending on what we want to do to the file, the main ones are given below:
writing files
Access Mode | Description |
r | Opens a file for reading only |
w | Opens a file for writing only. Create a new file if one does not exist. Overwrites file if it already exists. |
a | Append to the end of a file. Create a new file if one does not exist. |
read – Reads in the whole file into a single string
| f=open("filetxt","r") print(f.read()) f.close() |
readline – Reads in each line one at a time
| f=open("file.txt","r") print(f.readline()) print(f.readline()) print(f.readline()) f.close() |
readlines – Reads in the whole file into a list
| f=open("file.txt","r") print(f.readlines()) f.close() |
reading files
Write in single lines at a time | file=open("days.txt",'w') file.write("Monday\n") file.write("Tuesday\n") file.write("Wednesday\n") file.close()
|
Write in a list | say=["How\n”,”are\n”,”you\n”] file=open("say.txt",'w') file.writelines(say) file.close()
|
Year 10 Half Term 4: Computer networks, connections and protocols 1.3.1
Glossary:
Stand Alone- A single machine, not connected to another
Network- A collection of machines which can communicate with one another
Node -A device on a network (PC or other device)
LAN- Local Area Network (Single location)
WAN- Wide Area Network (Multiple connected locations)
WAP -Wireless Access Point
NIC - Network Interface Controller
Router -Controls the sending of data around a network
Hub - A central connection for a small network, which broadcasts all data to all clients
Switch -A smart hub for larger networks which only sends the data to the intended client
Internet -A worldwide collection of networks
WAP- WirelessAccess Point
A network is two or more computers connected together to share resources and data.
A network works by splitting bits of data up into small chunks called packets. These are sent between devices along wires or wireless connections until they arrive where they are meant to go and reassembled
.
Types of network
Local Area Network (LAN) covers a relatively small geographical area typically extends over the range of a single organisation such as a university campus, school site. LANs are usually managed by a single organisation.
Wide Area Network (WAN) made up of many local area networks and covers a much wider geographical area. The internet the ultimate WAN. It is a network of networks with billions of interconnected devices. No single person or organisation has control over a WAN
Advantages of networks | Disadvantages of networks |
Computers can share resources such as printers | Purchasing the network hardware is expensive |
Files can be accessed through any computer in the network | Managing a large network is complicated |
Data is easy to back up as it is stored centrally on the server | Viruses may be able to infiltrate the network and infect every computer |
LAN
WAN
Year 10 Half Term 4: Computer networks, connections and protocols 1.3.1
Glossary:
Stand Alone- A single machine, not connected to another
Network- A collection of machines which can communicate with one another
Node -A device on a network (PC or other device)
LAN- Local Area Network (Single location)
WAN- Wide Area Network (Multiple connected locations)
WAP -Wireless Access Point
NIC - Network Interface Controller
Router -Controls the sending of data around a network
Hub - A central connection for a small network, which broadcasts all data to all clients
Switch -A smart hub for larger networks which only sends the data to the intended client
Internet -A worldwide collection of networks
All clients need an NIC to connect to a ROUTER. This could be a wireless adapter or a network card.
The Router in this simple connection can host multiple clients, but more advanced hardware is needed for bigger networks
A Wireless Access Point connects wireless devices to a network. Many home wireless access points are part of a router
A Switch- A switch will behave like a hub when it is switched on, however it will learn which devices are connected to which ports, and then send packets directly to the correct computer, saving bandwidth.
Bandwidth- The more bandwidth the more traffic can pass through the network.
Connection speeds
This is similar to trying to get many cars through a single carriage road – so the ‘speed’ of the Internet connection will slow down in proportion to the amount of traffic that all the additional computers make.
Latency
latency is the length of time for a packet to travel through the network. A connection to a satellite will operate at the speed of light but has to travel 22,300 miles there and back. By contrast, two computers that are a few metres away will have incredibly low latency.
Number of user
Too many users at the same time can cause the network to slow down if the bandwidth is low
Transmission media
Wireless will be faster than wired connections
Fibre optic cables will transfer data faster then copper wire
Factors affecting network performance
Comparison of transmission media types
Year 10 Half Term 4: Computer networks, connections and protocols 1.3.2
Glossary:
Stand Alone- A single machine, not connected to another
Network- A collection of machines which can communicate with one another
Node -A device on a network (PC or other device)
LAN- Local Area Network (Single location)
WAN- Wide Area Network (Multiple connected locations)
WAP -Wireless Access Point
NIC - Network Interface Controller
Router -Controls the sending of data around a network
Hub - A central connection for a small network, which broadcasts all data to all clients
Switch -A smart hub for larger networks which only sends the data to the intended client
Internet -A worldwide collection of networks
WAP- WirelessAccess Point
| Advantages | Disadvantages |
wireless |
|
|
wired |
|
|
Wired V wireless network
| Advantages | Disadvantages |
2.4GHz | Greater range and coverage | More interference from other devices as this is a crowded frequency |
5GHz | Less crowded space with 23 non-overlapping channels with higher data transmission rates | Less able to penetrate through walls |
802.11 standards
802.11b/g/n uses the 2.4GHz frequency
802.11a/n/ac uses the 5GHz frequency
The most common wireless security standards are:
WEP (Wired Equivalent Privacy) and
WPA (Wi-Fi Protected Access)
The WEP method of encryption is older and can be cracked in seconds and should no longer be used to protect your home router
Year 10 Half Term 4: Computer networks, connections and protocols 1.3.2
Glossary:
Plaintext: the original message to be encrypted
Ciphertext: the encrypted message
Encryption: the process of converting plaintext into ciphertext
Key: a sequence of numbers used to encrypt or decrypt, often data using a mathematical formula
Encryption algorithm: the formula for encrypting the plaintext
Protocol The rules and standards that are agreed in order to make it possible for different devices to talk to one another
IP Address - Each node on a network is given a unique 32 bit address (4x8bits) for example 192.168.0.1 There are 4 billion possible combinations.
DHCP - Dynamic Host Configuration Protocol –this protocol allows the network server to control the allocation of IP addresses
MAC Address -Media Access Control
Unique addresses hard-coded into the network interface controller. Gives the manufacturer, NIC type and unique identifying number using 48 bits displayed as Hex
URL- Uniform Resource Locator. The address of a page on a website
Encryption is the encoding of data so that it can no longer be easily understood.
Encryption
The Caesar cipher is most basic type of encryption and the most insecure
Private key (Symmetric encryption)
A single key is used to encrypt and decrypt a message and must be given to the recipient of your message to decrypt �the data
Public key (Asymmetric encryption)
Two keys are used - one (public key) to encrypt and the other (private key) to decrypt data
This is more secure as it means that you never have to send or reveal your decryption key
IP addressing and MAC addressing
What is an IP address?
An IP address (Internet Protocol address) is the unique identification number given to every device that is connected to the internet.
An IP address changes if you take your device to another network location
An IP address may look like: 62.102.245.31
What is a MAC address?
A MAC address (Media Access Control address) is a unique number that identifies the actual device that is connected to the internet or network.
A MAC address does not change when you connect to the internet from different locations, it is part of the network interface card (NIC) inside your device
A MAC address may look like: 00 12 0E A6 B0 68
Year 10 Half Term 4:( (SQL) Additional programming techniques 2.2.3
Glossary:
Database- a data structure allowing you to store data
Table - an array that lets you hold the data in a database
made up of fields (columns) and records (rows)
Record- a store holding all the data about a particular item
SQL -Structured Query Language
which allows you to create, query and add data to databases
The SQL syntax for querying a database is:
SELECT … (list the fields to be displayed)
FROM … (specify the table name)
WHERE … (list the search criteria)
ORDER BY allows a query to sort data by ascending or descending order
Operator | What it does |
= | To see if one piece of data is equal to another piece of data |
<> | To see if one piece of data is not equal to another piece of data |
< | To see if one piece of data is less than another piece of data |
<= | To see if one piece of data is less than or equal to another piece of data |
> | To see if one piece of data is more than to another piece of data |
>= | To see if one piece of data is more than or equal to another piece of data |
IS NULL | To make sure no data is present in the column |
SQL common operators
SQL Logical Operators
Operator | Description |
AND | Comparing multiple pieces of data |
BETWEEN | Search for values that are within a minimum and maximum values |
IN | The IN operator is used to compare a value to a list of literal values that have been specified. |
LIKE | The LIKE operator is used to compare a value to similar values. |
NOT | Added to other operators to have the reverse effect. |
OR | Comparing alternative pieces of data. |
Year 10 Half Term 5: Identifying and preventing vulnerabilities 1.4.1
Glossary:
Hacking- Attempting to bypass a system’s security features to gain unauthorised access to a computer
Malware- software that has been purposely developed to damage, disrupt or take control of computer systems
Social engineering- People are the weakest point of any system. If a hacker can convince a user to give over their data, this is the easiest way into a secure system
Phishing-Phishing is a common way to try to steal information like passwords. Emails are sent, requesting the user logs into a website, but the site is a fake, and the users details are logged
Brute force attack- Using and algorithm to try every possible combination of characters to ‘guess’ the users password.
Denial of Service Attack - Hackers flood a network with huge amounts of fake data and requests in an attempt to overload the system so that it crashes
Data interception-Data interception, or Man in the Middle attacks are hacks that use ‘packet sniffer’ software to look at every piece of data being transmitted in the local area to find ones that meet the hacker’s criteria. Often done by creating ‘fake’ wireless networks to record users details
SQL injection- Using SQL statements to trick a database management system (DBMS) into providing large amounts of data to the hacker
Computer viruses replicate themselves and can transfer from one computer to another. They are activated by a user often as email attachments and attachment to other files and programs.
Trojan gains access to a computer by pretending to be legitimate software. The trojan allows unauthorised backdoor access to a computer without the user being aware.
Spyware records the activity on your computer such as your keystrokes, thereby logging your passwords for instance and then send the data back over the network to a hacker. Spyware can also be used to control your webcam and microphone.
Adware includes banners and popups that are automatically installed onto a computer. Whilst this does not cause any, adware is undesirable and can slow down the performance of a computer.
Worms spread like viruses but do not require human intervention. They attach themselves to network tools to spread automatically around a network very quickly.
|
Malware
Denial of service attack
Data interception
SQL injection
Year 10 Half Term 5: Identifying and preventing vulnerabilities 1.4.1
Glossary:
Hacking- Attempting to bypass a system’s security features to gain unauthorised access to a computer
Malware- software that has been purposely developed to damage, disrupt or take control of computer systems
Social engineering- People are the weakest point of any system. If a hacker can convince a user to give over their data, this is the easiest way into a secure system
Phishing-Phishing is a common way to try to steal information like passwords. Emails are sent, requesting the user logs into a website, but the site is a fake, and the users details are logged
Brute force attack- Using and algorithm to try every possible combination of characters to ‘guess’ the users password.
Denial of Service Attack - Hackers flood a network with huge amounts of fake data and requests in an attempt to overload the system so that it crashes
Data interception-Data interception, or Man in the Middle attacks are hacks that use ‘packet sniffer’ software to look at every piece of data being transmitted in the local area to find ones that meet the hacker’s criteria. Often done by creating ‘fake’ wireless networks to record users details
SQL injection- Using SQL statements to trick a database management system (DBMS) into providing large amounts of data to the hacker
Social engineering
Blagging (Pretexting) Fraudsters make up a scenario to con victims into revealing something they would not ordinarily do. They may have found out some personal information about you from social media sites, to pretend they already know you.
How to prevent
•Use biometric measures because these cannot be divulged.
•Ensure you have your privacy settings on any social media to maximum so that fraudsters cannot find information about you such as your date of birth, where you live etc.
Phishing Normally an email or text messaging scam where victims are conned into believing that they are being contacted by their bank for instance and can give sensitive personal details such as bank account passwords.
How to prevent
•Awareness and vigilance. Be particularly aware of unsolicited texts, emails and phone calls. Do not give personal confidential information away. Official organisations such as banks will never ask for this information.
•Apply email filtering to prevent dubious emails getting through.
Pharming Users are redirected to a fraudulent website that they believe to be genuine because it looks like the real site. For instance, you could be directed site that pretends to be an online store that asks you for your credit card information.
How to prevent
•Check the URL in the web address. For secure websites such as banking or e-commerce sites the HTTPS protocol should be used.
•Website filter
Shoulder surfing Fraudsters look over the shoulder of users to see what passwords or pin numbers that are being typed into the device. This can easily occur at computer terminals and at ATMs that are out in the street.
How to prevent
•Be aware of who is around you when typing in your pin into an ATM or into a chip and pin device. Make sure you cover your hands and they are shielded from prying eyes.
•Place computers in locations that makes shoulder surfing difficult
Year 10 Half Term 5: Identifying and preventing vulnerabilities 1.4.2
Glossary:
Anti- malware
preventing installation of harmful software, preventing important
files from being changed, scanning for virus activity on the system
and removing as appropriate. Antimalware protects against
worms, Trojan Horses, spyware, adware and keyloggers.
Antivirus Software designed to protect against viruses.
Malware Updates
New malware is released regularly and so anti‐malware definitions
must be up‐to‐date to protect form the latest viruses.
Firewall
Hardware or software designed to prevent unauthorised access to
or from a private network or intranet. All messages entering or
leaving the network will pass through the firewall to be examined.
Password Protection
In a networked environment such as a school or a company,
multiple users use many of the computers. Passwords should be
strong (Not easy to guess, lower and uppercase letters, numbers,
symbols).
Physical security- using guards, pins, id cards, cctv cameras, locking areas off, all methods to prevent physical entry to data by unauthorised persons.
Encryption
Changing data before transmission so someone can only decipher it with the appropriate key to unlock information. Interceptors would find the message unintelligible. read slide 19 for details
Penetration (Pen)
-Gathering information about the target of possible attacks
-Identifying possible entry points to the network
Testing -Attempting to break in
-Report findings and respond.
Internal Pen Testing
Puts the tester in the position of an employee with standard access
rights to the network to determine how much damage they could do.
External Pen Testing
May target servers within a business to see how easy they are to break
and how it can be achieved.
Firewalls
The firewall will detect packets from malicious computers
Password policy
Organisations and computer systems will often have password policies. These will �make sure that your chosen password has features like:
Physical security
Physical security is where hardware, software and networks are protected by physical methods
CCTV
Intruder alarms
Locks on doors or cabinets
Fences, walls, barbed wire
Security guards
ID cards and signs
Turnstiles and gates
User access levels
Access rights may be set on disks, folders and even individual files. Staff will have different levels of access to these files.
Year 10 Half Term 6: 1.3.1 Computer networks, connections and protocols
TOPOLOGY | DIAGRAM | DESCRIPTION | ADVANTAGE | DISADVANTAGE |
Star | | In a star network, computers and other devices (known as nodes) are all connected to a �central switch |
| . Requires additional hardware such as the central switch and network cables . If the central switch fails the whole network goes down |
Full Mesh | | Nodes act as routers for data in order to relay and propagate data in the network |
| . Can involve redundant connections . Expensive to install cabling if using wired connections . Network maintenance and administration is difficult |
Network topologies
A topology is connections between computers and how they are connected
Server
Printer
Switch/Hub
Computer
Computers
Computers
The Internet is highly complex as it combines many networks together, but many parts operate as a partial mesh
PARTIAL MESH
Year 10 Half Term 6: 1.3.1 Computer networks, connections and protocols
Glossary:
TCP/IP Transmission Control Protocol / Internet Protocol A set of protocols that governs the transfer of data over a network
HTTP- Hyper Text Transfer Protocol Standards for writing webpages to display content for display
HTTPS Hyper Text Transfer Protocol Secure Client-server protocol for requesting (client) and delivering (server) resources, such as HTML, securely
FTP- File Transfer Protocol Used to directly send files from one node to another over the internet. Commonly used for uploading files to webservers
POP- Post Office Protocol Used by email clients to download email from the remote email server and save it onto the users computer. More or less redundant now, and has been replaced by IMAP
IMAP- Internet Message Access Protocol. An alternative to POP, allowing more control such as the complete control of remote mailboxes
SMTP- Simple Mail Transfer Protocol An old standard for transmission of email. SMTP can only be used to push mail to client machines, whilst both POP and IMAP ae used by clients to retrieve mail.
Layering Rules organised into a distinct order in
Interoperability- The ability for different systems and software to communicate, exchange data and use the information exchanged
Encapsulation- Enclosing data inside another data structure to form a single component
De-encapsulation- Removing data from inside and
The word ‘Protocols’ refers to the set of rules and standards that define how digital devices communicate with each other
Standards-
Allow hardware and software to interact across different manufacturers.
Standards apply to cabling, Ethernet, and connectivity. A network standard specifies the way computers access a network. For instance the speed, the type of cabling, and wireless technology used.
The Institute of Electrical and Electronic Engineer (IEEE), is one international organization responsible for developing and providing networking technology specification for worldwide usage
Year 10 Half Term 6: 1.3.1 Computer networks, connections and protocols
Glossary:
TCP/IP Transmission Control Protocol / Internet Protocol A set of protocols that governs the transfer of data over a network
HTTP- Hyper Text Transfer Protocol Standards for writing webpages to display content for display
HTTPS Hyper Text Transfer Protocol Secure Client-server protocol for requesting (client) and delivering (server) resources, such as HTML, securely
FTP- File Transfer Protocol Used to directly send files from one node to another over the internet. Commonly used for uploading files to webservers
POP- Post Office Protocol Used by email clients to download email from the remote email server and save it onto the users computer. More or less redundant now, and has been replaced by IMAP
IMAP- Internet Message Access Protocol. An alternative to POP, allowing more control such as the complete control of remote mailboxes
SMTP- Simple Mail Transfer Protocol An old standard for transmission of email. SMTP can only be used to push mail to client machines, whilst both POP and IMAP ae used by clients to retrieve mail.
Layering Rules organised into a distinct order in
Interoperability- The ability for different systems and software to communicate, exchange data and use the information exchanged
Encapsulation- Enclosing data inside another data structure to form a single component
De-encapsulation- Removing data from inside and
Layering allows problems to be broken down into small chunks, and then smaller solutions created to solve specific parts of the problem. An advantage is, these small parts interact in an agreed manner, allowing the solution to be built by different teams or companies.
TCP/IP model has 4 layers, with each layer responsible for a small part of the communication between two devices.
4
3
2
1
Year 11 Half Term 1: 2.3 – Producing robust programs
Glossary:
Defensive design- Planning a program from the very beginning to prevent accidental or purposeful misuse
Input sanitization- Removing erroneous data from a system prior to processing
Data validation- Ensuring all data is in the correct format prior to processing
Contingency planning- Having built in checks and outcomes based on what happens when things go wrong
Anticipating misuse- Building programs which do not allow a user to deliberately break the system
Authentication- Having different levels of user, and preventing everyday users from being able to significantly change a system
Anticipating misuse
Apart from anticipating accidental user errors, steps have to be taken to prevent deliberate misuse, for example attempts to guess a password with a brute-force attack.
Authentication
Authentication routines are used to make sure a person is who they claim to be. It can be facial recognition, fingerprint recognition or password. When you first came to this school you were given a user name and password. the password is saved to a database and used to match your username when you next login. If your password is incorrect an error message is displayed
Data validation
Data validation routines can ensure that data entered is of the right type – for example, a number instead of a letter . However:
Check | Example |
Range check | A number or date is within a sensible/allowed range |
Type check | Data is of the right type, such as integer, letter or text |
Length check | Text entered is not too long or too short – for example, a password is between 8 and 15 characters |
Presence check | Checks that data has been entered, i.e. the field has not been left blank |
Format check | Checks that the format of, for example, a postcode or email address is correct |
Used to double-check that the data has been typed in correctly
When setting a new password you may be asked to type it in twice
If the two passwords don’t match, you will be asked to enter the password again. This is known as double-entry verification
Data Verification
Year 11 Half Term 1: 2.3 – Producing robust programs
Glossary
Maintainability- Building software which is modular to enable sections to be updated and replaced without having to write the whole program again from scratch
Code comments- Annotating code so that the person maintaining or working with your code in the future is able to understand your thought process
Indentation - Making code more readable by laying it out in a manner that keeps sections of code separate
There are a number of techniques that will make programs easier to maintain. Maintaining ensures bug are fixed, or new features are possible to add.
Use of sub programs
Naming conventions
Indentation
Commenting
Sub programs include functions and procedures. Well written sub programs will take inputs (through parameters) and if necessary return a value
function circle(radius)� area = 3.14 * radius^2�return area
comments are used so that anyone (including your future self) who may need to maintain or extend your code.
Use a hashtag to add a comment to show what a function or procedure is doing. Don’t use them for every line of code in your program
Indentation is used so that it easy to see which lines of code are part of different structures
Naming variable/constants/ subroutines in programs is very important. You should have names that make it very clear as to what the structure is storing
a = input()�b = input()�print (‘hello’, A + b, ‘ how old are you ?’)�
firstName = input()�surname = input()�print (‘hello’, firstName + surname, ‘ how old are you ?’)�
🗶
✔
Year 11 Half Term 1: 2.3 – Producing robust programs
Glossary:
Iterative testing- Step by step testing to ensure that small sections of the code work, before new parts are added and then retested. Important to allow tracebackto find what caused any errors
Terminal testing- Significant testing done once a program is complete under a range of conditions and on multiple hardware –often called Alpha Testing
Beta Testing - Making a small release of the software to a group of tech-literate enthusiasts to broaden the usage-testing and get lots of feedback prior to full release.
syntax error- An error in the typing of the code. Missing punctuation, spacing etc
Test data - Data chosen to test the program. Testers use a specific range of data
Normal data- The data that will be used to check the code works correctly
Valid Data- Obvious data which should definitely pass
Boundary data- checks lowest valid data and checks highest valid data
Invalid Data- data that is outside the boundaries of valid data
Erroneous Data- Data that is the wrong type and should fail
Expected Outcome -The data the code should output if it is running correctly
The purpose of testing is to ensure programs run as intended.
Types of testing:
Iterative
tests modules and parts of a program �as the program is developed
Final/terminal
Carried out when the program is completed. All parts of the program are tested to accept correct user entries and that all required functions are included
Identify syntax and logic errors
Program: enter a number between 1 and 100
Normal data: 5 (checks a single digit), 14 (checks two digits)
Boundary data: 1 (checks lowest valid data), 100 (checks highest valid data)
Invalid data: -50 (checks negative numbers), 173 (checks data of the correct type that is invalid), 0 (checks just below lower boundary), 101 (checks just above upper boundary)
Erroneous: "ade", "#$" (checks data of the wrong type is rejected)
Syntax errors
Translators expect programs to have a certain format called ‘syntax’. Eg. Missing a parenthesis, or a comma
Logic errors
These occur when the program does not return the expected results. A Typical error might be brackets in the wrong place.
examples of test data
Year 11 Half Term 2: NEA
Review the NEA structure that may be helpful to complete the controlled assessment tasks
ANALYSIS
DESIGN
DEVELOPMENT
TESTING
AND EVALUATION
Year 11 Half Term 3: 1.3.1 Networks and topologies
Glossary:
Client-
client is a piece of computer hardware or software that
accesses a service made available by a server.
Server
A server is an instance of a computer program that accepts and responds to requests made by another program, known
as a client.
Peer-to-peer – computers networked together to provide support without a central server
Client-server – a network which has a client machine/s and a server which provides the service required by the client
client-server network
peer-to-peer networks
Type of network | advantages | disadvantages |
Client- server network | File servers- just one file server needs to be backed up and files can be accessed from any computer Email servers - provide a central place for email that is then accessed from different devices Print server - can manage all files to be printed. This allows one printer to be shared by many computers | All users are reliant on the central server High cost of servers Need expert to configure the network |
Peer to peer network | Easier to set up – computers can simply be cabled together No need for dedicated server equipment Individual computers can share a printer, router, modem and other hardware Users can communicate directly with each other and share each others’ files | Viruses and malware are more easily transferred each computer has to have its own backup system hard to locate files if the computer’s owner does not have a logical filing and naming system If a computer is switched off, data cannot be retrieved from other machines |
A single high-spec machine is designated the server, which includes the main file storage. Each client then requestsdata from the server which responds and fulfills the request.
A distributedsystem where each node is equal. Every computer can serve and request data from all others. The system is easy to set up, but slow and difficult to administer.
Year 10 Half Term 3:
Glossary:
DNS- Domain Name Server
Hosting Storing a file on a web-server foraccess via the internet
Cloud- A service which is stored remotely
WWW- WorldWide Web -Pages of content
Email- Electronicmail, sent through the internet
URL - Unique Resource Location
Year 11 Half Term 3: 1.3.1 Networks and topologies
A service offered by companies that will host web pages and files for websites
The web hosts will often provide database servers
Companies that provide more general hosting, such as backup servers, are known as hosting service providers
Advantages of using a web host over sharing files from your own computer include:
Web hosts have far more bandwidth – so they can serve more users
Web hosts are able to monitor their equipment 24 hours a day
Web hosts will backup web sites remotely
Web hosting
The ‘Cloud’ is a term used to refer to services that are delivered over the Internet
examples include Google Drive, OneDrive and Dropbox.
Cloud remote Services include storage, software processing such as databases, word processing , spreadsheets, apps. The software can be accessed from any Internet-connected computer, including smartphones
The cloud-
Advantages | Disadvantages |
You can access your data and applications from anywhere at any time You don’t need a powerful computer with a huge hard drive – everything is stored and run on a remote computer Backing up data is no longer crucial – it is done by the �service provider | Personal data will be stored on another company’s servers If the Internet connection is lost, often the service �becomes unusable Slow Internet connections may result in a poor quality �of service Although most cloud services will backup data stored with them, it is not easy for people and organisations to see how resilient this is |
See slide 17 of the year 10 knowledge organiser to remind yourself of factors affecting pc performacne
Year 11 Half Term 3: 1.3.1 Networks and topologies
Glossary:
DNS- Domain Name Server
Hosting Storing a file on a web-server foraccess via the internet
Cloud- A service which is stored remotely
WWW- WorldWide Web -Pages of content
Email- Electronicmail, sent through the internet
URL - Unique Resource Location
The URL (uniform resource locator) for a website includes the host name. For example, the host name bbc.co.uk is included in the URL www.bbc.co.uk.
The host name consists of three hierarchical levels, which work in reverse order of the name:
�
Every website on the internet has a network address, consisting of four sets of three digits. For example, the BBC website's address is 151.101.128.81.
Addresses like this are hard for users to remember. Instead, websites are accessed using domain names, for example, ‘bbc.co.uk’. Domain names are much easier for users to remember.
When a user visits a website, they enter the domain name as a URL. For example, the BBC website’s address is www.bbc.co.uk. A domain name server takes the domain name and looks up its equivalent network address. The user’s request is then forwarded to the server that resides at that network address.
DNS
Glossary:
Utility Software
Data Compressions
Allows files to be made smaller by removal of empty space or through compression algorithms (lossy or lossless
Lossy Compression - Data is removed from the file to make it smaller. This data is lost and cannot be regained. Suitable where the loss of data is likely not to be noticed. Eg images
Lossless Compression- No data is lost, but rather rearranged to ensure a perfect version of the data can be returned. Used where exact reproduction is vital. Eg text documents
Lossy compression (JPG, GIF, MP3)
Lossless compression (PNG, TIFF)
Advantages of compression
|
File �format | Type of compression | File �usage |
JPEG | Lossy | Photos |
PNG | Lossless | Images/photos, may include transparency |
ZIP | Lossless | Document compression |
GIF | Lossless | Simple images, may include animation |
MP4 | Lossy | Video file format |
MP3 | Lossy | Music format |
FLAC / ALAC | Lossless | Lossless Music format (Free / Apple) |
Year 11 Half Term 4: 1.2.5 compression
Year 11 Half Term 4: 1.2.5 compression
Year 11 Half Term 4: 2.5 – Programming languages and Integrated Development Environments
Glossary:
Low level language- machine code language that is written in Binary code which the CPU can understand
High level languages - Programming languages that are most like human language
Assembly language- use pneumonic which have to be converted to binary by an assembler
Instruction set - The complete set of instructions that a processor can handle
Translator
A program that converts source code (High level) to machine code (Low
Level).
Compiler –translates high level language code to machine code once re program has been programmed
Interpreter – translates code to machine language one line at a time
Source code - The program written in a high‐level language before it is converted to Machine code.
Object code - The machine code produced by a computer.
Machine independent - programs in high level languages which can run on different types of processors.
1000101100000100001001010011001100000000000000000000000000000101111111110000000000000000000000001000100100000100001001010011010000000000
Year 11 Half Term 4: 2.5 – Programming languages and Integrated Development Environments
Glossary:
Integrated Development Environment (IDE)-They have a number of tools and features that help programmers when they are programming
editors – essentially part of an IDE. Has features such as autocomplete, colour match, bracket match
Error diagnostics (debugging) – help a programmer to find where they have made a mistake
Run-time environment -allows a programmer to test their program while it is running
Syntax highlighting
Line numbers
Code folding
Breakpoints, variable watch, stepping
Features of an IDE, that can help a programmer in writing error free code.
When errors are found, the line number that they occur on will also be stated
In some IDEs, parts of the program that the programmer doesn’t need to see can be folded
the colour of the text changes to show different parts of the program
Breakpoints are set by the programmer so that the IDE pauses the program when running and then run each line of code separately whilst watching the values stored in variables as they change
Run-time environment – The facility of the IDE that allows programs to be run
Year 11 Half Term 4: 1.6 – Ethical, legal, cultural and environmental impacts of digital technology
Glossary:
Ethical- refers to a moral sense than a legal issue. For example, there is nothing to stop you legally from using Facebook to stalk an ex-partner, but whether it is right to do so, is an ethical issue
Legal- There are certain laws set by government that control how computers can be used –see box
Cultural- These issues relate to society and how technology can affect religious, or social ideas. If people spend all their time on their phones rather than talking face to face, this is a cultural issue
Environmental- How computing impacts on the global and local environments. This might be waste production, or mining to gather resources needed to make phones, or using renewable energy to charge phones, or recycling projects. Companies want to be seen to be ‘green’.
Privacy- Privacy is a very important issue. A persons right to privacy is very important and there are strong law, alongside ethical guidance that govern how companies can use our data
Open source- Software that is created and shared with the source-code able to be seen. Users are free to make alterations to the source-code to meet their own needs, or to improve the system for everyone
Proprietary- Software that is created but the source code is locked. This is often sold and the company wants to protect its intellectual copyright
Legislation- Laws that have been created and passed by parliament thus affecting us all.
Disposal – to get rid of something. Example an old computer
Data protection – a law created to protect the use of data
Computer misuse – using a computer to cause harm to an individual or company
Software licence - types of licence which state how software can be used/distributed
Digital technologies are electronic systems, devices and resources that generate, store or process data. When using digital technologies we all have moral and ethical responsibilities to consider. There a number of laws which we must follow.
Ethical issues - What is good for individuals and society NOT what is legal e.g.
it’s not illegal for you to tell lies
but is it ethical?
Cultural issues - Computer matters that have an effect on the nature and culture of society. Some of these issues include:
Environmental issues –Technology has had good and negative impacts on the environment. The negatives are throwing away machines which then harm the environment, positives are that newer machines use energy efficiency technologies. Recycling components.
https://www.pbs.org/newshour/science/america-e-waste-gps-tracker-tells-all-earthfix
Privacy issues – organisations and governments collect huge amounts of data about us. This is often supplied by internet sites and telephone companies
Year 11 Half Term 4: 1.6 – Ethical, legal, cultural and environmental impacts of digital technology
Glossary:
Ethical- refers to a moral sense than a legal issue. For example, there is nothing to stop you legally from using Facebook to stalk an ex-partner, but whether it is right to do so, is an ethical issue
Legal- There are certain laws set by government that control how computers can be used –see box
Cultural- These issues relate to society and how technology can affect religious, or social ideas. If people spend all their time on their phones rather than talking face to face, this is a cultural issue
Environmental- How computing impacts on the global and local environments. This might be waste production, or mining to gather resources needed to make phones, or using renewable energy to charge phones, or recycling projects. Companies want to be seen to be ‘green’.
Privacy Privacy is a very important issue. A persons right to privacy is very important and there are strong law, alongside ethical guidance that govern how companies can use our data
Open source Software that is created and shared with the source-code able to be seen. Users are free to make alterations to the source-code to meet their own needs, or to improve the system for everyone
Proprietary Software that is created but the source code is locked. This is often sold and the company wants to protect its intellectual copyright
Legislation- Laws that have been created and passed by parliament thus affecting us all.
Disposal – to get rid of something. Example; an old computer
Data protection – a law created to protect the use of data
Computer misuse – using a computer to cause harm to an individual or company
Software licence - types of licence which state how software can be used/distributed
Legislation | description |
The data Protection Act 2018 | Being responsible for the data of users. The key principles of the Data Protection Act and GDPR are:
Make sure you revise the content of each principle |
Computing Misuse Act 1990 | This was passed by Parliament and made three new offences:
|
Copyright Designs And Patents Act 1988 | This Act gives creators of digital media the rights to control how their work is used and distributed. Music, books, videos, games and software can all be covered by copyright law. Anything which you design or code is automatically copyrighted and may not be copied without your permission, as the digital creator. |
Software Licence |
|
Year 11 Half Term 5 & 6: revision
Task 1-Create concept maps of each topic in the specification
Task 2- use your concept maps to add information to ‘‘ The complete OCR revision booklet’ in resource area