Algorithm strategy: OCR Land Example

Tackling Algorithm Questions

• Variables require identification of arrays along with necessary variables
• Number variables must be initialized to 0
• Requires questioning of the data forming the conditional statements (ifs)
• Checks must be performed for necessary mathematical operations.
• Running totals may be required
  • This can be achieved using variable = variable + 1
• Task repetition needs to be considered
  • The number of repetitions also needs to be known

OCR Land Algorithm Example

• Theme park OCR Land sells tickets online for £19.99 (adult) and £8.99 (child), plus £2.50 booking fee
• A ride has height restrictions: 140 cm to ride alone or 120 cm with an adult
• A program is needed that:
  • Obtains the rider's height in centimeters
  • Asks if the rider is with an adult if needed
  • States whether the rider can ride
  • Repeats for 8 people
• Integer variables store height and the number of people
• A boolean variable tracks adult accompaniment
• The questions needed are:
  • Is the height ≥ 140 cm?
  • Is the height ≥ 120 cm and accompanied by an adult?
• There are no calculations required
• Requires 8 repeats ("Do not know - 8 people max")

All About the CPU

• CPU stands for Central Processing Unit
• The CPU fetches and decodes instructions from the Main Memory (RAM)

Characteristics of a CPU: Clock Speed

• CPUs use a clock to organize computer components
• Clock speed is measured in GigaHertz (GHz)
• Higher frequency processing allows more instructions per second

Characteristics of a CPU: Cores

• A core is a processing unit
• More cores allow CPUs to process more instructions
  • CPUs can be single-core, dual-core (2 cores), or quad-core (4 cores)

Advantages of Multiple Cores

• Tasks split between cores speed up processing
• Multitasking is enabled
  • Runs more than one task at a time

Disadvantages of Multiple Cores

• Not all applications utilize multiple cores
• Some tasks cannot be shared between cores
• More cores also increase processor cost

Cache

• CPUs have cache, a small amount of memory
• Cache stores frequently used instructions/data
• Instructions are accessed from cache quicker, which reduces RAM needs
• More cache allows quicker instruction processing
• Excessive cache slows down instruction finding

Example Question (CPU Specs)

• Computer 1: 1 GHz clock speed, 2 MB cache, 4 cores
• Computer 2: 1.4 GHz clock speed, 2 MB cache, 2 cores
• Cache size impacts CPU performance
  • Faster data transfers make CPUs more efficient
  • Transfers to/from cache are quicker than RAM

Question for Jim

• Jim needs a new processor for multitasking software
• A processor is needed that is best, including a reason

Fetch-Decode-Execute Cycle

• This cycle is also known as the Von Neumann Architecture
• Data and instructions are stored in memory (RAM) as binary digits
• A processor decodes and executes instructions serially and fetches the next instruction
• The cycle stops when there are no more instructions

Fetch: Registers Used

• Used registers are small pieces of memory
• Registers used in the Fetch stage:
  • PC (Program Counter): Stores next instruction address in memory
  • MAR (Memory Address Register): Stores the address in memory to read
  • MDR (Memory Data Register): Stores data or instruction fetched or read from memory
  • CIR (Current Instruction Register): Stores the instruction being processed

Decode: Registers Used

• MDR and MAR registers may be needed
• The control unit (NOT a register) splits instructions into OpCode and Operand
  • The OpCode outlines the operation
  • The Operand supplies data/address for the operation

Execute: Registers Used

• The accumulator stores process/calculation results
• The Arithmetic Logic Unit (ALU) component carries out calculations

Fetch Example

• The user double-clicks a program shortcut on the desktop
• The program is then loaded into RAM
• PC moves the next address
  • CPU starts with the first line of the program (A9)
• MAR holds A9, the location of the instruction in RAM
• CIR then gets content from MDR
  • Holds 01001 000011 (the instruction from address A9)

Decode: Example Details

• The CPU performs decoding
• The control unit breaks the instruction: 01001 000011
  • 01001 is the OpCode, which the control unit checks to determine the meaning
  • 000011 is the Operand, a value
  • 01001 means LOAD
  • 000011 has a value of 3

Execute: Accumulator Example

• In execution, the accumulator gets the value
  • Accumulator stores 000011

Memory Overview

• ROM (Read-Only Memory) vs RAM (Random Access Memory) - Both needed by your devices (PCs, laptops, tablets, smartphones, smart watches, Sat Navs)
  • ROM is Read Only Memory
  • RAM is Random Access Memory

ROM Details

• ROM holds the instructions to boot up the OS via the Bootstrap Loader
• Non-volatile (instructions are permanent)
• Capacity is measured in megabytes
  • Typically 16-32MB
• Cannot be upgraded
  • Built into the motherboard
• Instructions are read-only
• ROM is typically used by the CPU
• Small power consumption

RAM Details

• RAM stores running program instructions/data
• Data is erased when power is lost (volatile)
• Measured in gigabytes
  • 1, 2, 4, 8, 16, 32, 64 GB
• RAM can be upgraded, dependent on the motherboard
• Programs/OSs can read/write from RAM
• DIMM RAM is used by PCs, SODIMM RAM by laptops

When Virtual Memory is Useful

• Virtual memory is used when main memory is full
• Virtual memory is part of secondary storage
• VM usage includes:
  • RAM data is moved to VM, which frees up space
  • RAM then fills with new data
  • VM data is moved back to RAM as needed

Virtual Memory Implications

• Increasing RAM is better
  • VM is slower than direct RAM access
  • Moving data between RAM and VM takes processor time

Example question, regarding ROM, RAM and VM

• Alicia has designed a computer using Von Neumann architecture with 2GB of RAM

  • Alicia says virtual memory can compensate for the lack of RAM

• Virtual memory can compensate for the lack of RAM

• VM is used when RAM is full

• It is part of the secondary storage, used as (temporary) RAM/VM

• RAM data is moved to the secondary storage/VM to make space in RAM

  • RAM can then receive new data
  • VM data is moved back into RAM when it needs to be used

Secondary Storage

• A secondary storage device stores files when the computer is turned off. In addition to personal files and applications, it also stores the OS.

Magnetic Hard Drive (HDD)

• HDDs contain moving parts.
• They are not portable, but are found in old laptops.
• Fairly heavy.
• They are a reliable and cheap option.
• Holds the largest capacity out of all storage mediums.

Solid State Drive (SSD)

• SSDs are a newer, more expensive technology.
• They can be found in mobile phones, so they are portable.
• These have no moving parts, which makes them durable.
• Fast at reading & writing data.
• Contain a reasonable amount of storage.

Optical Disk (CD/DVD/Blu-Ray)

• These disks are extremely cheap to make and distribute.
• But they are easily damaged (scratched) and have a limited capacity. (CDs are mostly used for music files).
• Easy to take with you.
• Not all of these optical disks can be written on. e.g. CD-R is a recordable Compact Disc

Where are optical disks used?

• To Distribute Music
• Films, Video games, and various Software.

Selecting Storage Mediums

• Portability: How easy to move medium around
• Reliability: How long the storage will continue to work as expected.
• Durability: Will knocks and scratches damage it?
• Capacity: Limitations on the amount of data that can be stored on the medium
• Capacity doesn't always relate to size of medium.
• Speed (Read / write): How long will It take to load a game / write work
• cost: Is the technology new and complicated to manufacture, raising costs?

Choosing a Storage Device Carefully

• Secondary storage considerations include the capacity/size, speed, and portability
• Other Considerations are durability, reliability, and cost.

Binary Basics

• Computers use the binary number system different from our denary system. CPUs process binary instructions using Machine Code, which is hard for humans to understand.
• Binary is Base 2 using only 0 and 1.
• A binary digit is created by a transistor.
  • Electricity signal = 1; no signal = 0.

Multiple Bits

• More bits = larger numbers
• Add extra digits to the left
• 4 bits = 'Nibble' = max value = 15.
• 8 bits = 'Byte" = max value = 255.

Converting from Binary to Denary

• Make a table, # columns depends on # bits
  • Top row = value for each bit, bottom row = binary number
  • value doubles every added binary digit.
• Start from right and always start with 1.
• Add the value to total there's 1.

Denary to Binary

• Numbers to 255 can be done using 8 bit.
• Make the table with 2 rows, 8 columns
  • Place value 1 starting from RIGHT in 1st space. Moving to double PREVIOUS value on the right

Converting to Binary Part 2

• There's 1 way to represent a number, which values make number when added.
• If value is needed, place 1 in box below the value. If value is unneeded, place 0.

Example Binary Question

• The binary number needs to be converted to denary, including the working

Binary Addition

• Binary values can be added using specific rules:
  • 0 + 0 = 0; 1 + 0 = 1; 0+1=1; 1 + 1 = 10
• Follow the rules from right to left
  • Carry the 1 to the next column when the sum is 10

Example Binary Addition

• Add the binary numbers for an example broken down
  • Adding the first 4 bits and then the last 4 bits

Binary Shifts

• Binary shifts multiply or divide binary numbers by moving digits to the left (multiply) or right (divide)

Steps for Multiplying through Binary Shifts

• For multiplying (shift to the left):
  • Add a 0 to the right for every required shift
  • Delete leftmost digit if necessary
• For dividing (shift to the right):
  • Add a 0 to the front for every shift needed
  • Move digits to the other side of the binary point and strike it out

Number Bases

• Binary system is Base 2
• Denary system is Base 10

Base 16 (Hexadecimal)

• Hexadecimal is an easier way to remember binary values
  • Humans, not computers, can understand hexadecimal
  • Needs to be translated to binary
• Each value is from characters 0-9 and A-F
  • A hexadecimal value is used to represent color

Relating Hexadecimal

• Know how to convert the 2 number systems
• Two hexadecimal characters are equivalent to 255
  • 15 x 16 = 240
  • 15 in hex is F; 240-255 = 15
  • Another 15 in hex is F; FF is 255 in hex

Character Sets

• Needed to display characters/symbols on the computer
• Each letter converted to character code (binary number)
• Each character has a unique code

ASCII - the 1960s

• Original character set standard (American Standard Code for Information Interchange)
• Able to represented upto 128 characters
• Used 7 Bits
  • "A" = 1000001

ASCII (extended)

• Allowed non English countries (European) supported
• Extra bit was added to length of code allowing upto 256 characters
  • "A" = 01000001

ASCII difference

• ASCII (1960) 7 bit version had 128 Symbols which was enough for just English with punctuations
• ASCII (extended) 8 bit version has 256 Symbols and able to represent European characters

Binary ASCII

• Letter A is 65, Z is 90
• Lowercase 'a' is 97, lowercase 'z' is 122
• Table codes in Binary
  • A = 01000001 (65)
  • a = 01100001 (97)

Unicode

• More space to store more characters
• Consists of 16 bits - Enoguh space for 65536 characters/punctuation
  • Almost every character including emojis can be stored using Unicode
  • '0'=1100001110111000

Example ASCII word usage

Ascii A= 65 s= 115 c= 99 I= 105

Character Set Questions

• Character sets represent string values stored in the variable
  • Each character has unique binary number
• The example is binary values

Main Information of Audio

• To store and send audio on a computer, it must be converted to a digital format or audio recording software.

Sampling

• Height/amplitude of waveform sampled/measured
• converted/stored as binary/digital
• Sampled/measurements taken at regular interval/set interval by sampling

Example:

• A radio station records an interview with a computer scientist using a comp using sampling is used to store audio recording

Images

• All images have to be represented using binary
• Images made up of square pixels
• Each pixel represents a single color
• Each pixel has a unique binary code

Color Depth

• The more colors needed in an image, the more bits are needed
  • An image of 8 different colors would require 3 bits per pixel

Images Size

• The number of pixels that make up the image
• Height x Width

Meta Data

• Graphic files contain extra data about the image

Bitmap Images

• An Image is made up of / Consists of pixels
• A pixel is one-color
• Each color has a unique Binary number\

File Size Reduction

• Reducing the number of colors and pixels reduces file size, compression such as lossy/lossless

Networks

• Two or more computers that are connected together either wirelessly or with cables.

Networking. Why Needed

• To communicate with others and share resources (files, printers...)
• Network hardware includes
  • Network card(Nic): Computer can connect to a Network. Gives a computer Mac Address
  • Switch Storing Mac addresses to all connected devices. Found at center of Network.
    • Router. Connects to Internet service Provider( ISP).
  • Use ip addresses to
  • forward packets access internet

Networking types

• LAN (local area netwerk)
  • -Small geographical area
  • Using their own devices
  • -homes, schools, offices are examples of LANS
• WAN (wide area network)
  • Wide geographical
  • Leases and connects to the internet.

Networking adresses/ip

• Mac adress: Used in lans to identify devices
  • Hardcoded hexademical 48 bit in size
  • Example : 32A22e: 55555. Ip Adresses: Ip address is given to a computer as it's connected to a network

Networking: type of servers.

• client server -Server is used. Files and software stored on central server.
  • Need technical staff to run large scaled deployment Peer to peer
  • no severs equal - Each back security responsibility commonly
• Found at home

Packets

Packets are used to send data each with a certain details so its arrives at the correct Distention. Has a destination and sender Mac, Sequence number, IP, and error checking

Packets information

• Bandwidth is the maximun amount of data that can travel A communications channel in a given time • Frequency the delay between signal is sent to receive.
• Networking, wireless and Etherner.

Network Performance

• In terms of Wi-fi frequencies
  • More data can be carried per second when greater frequency is achieved
  • Range suffers

What can increase Network Traffic

• Objects and distance.

Network Topologies and Layouts

• Includes Types such as STAR topology. Where is switch is at center and MESH topology.
• Star
  • • If cable/node fails the networks is unaffected .
  • managed easy to other nodes
  • to add,Constant performance
  • -Requires technical skil, Equipment cable to set up a lot of skills.
• Mesh
  • New Nodes not affecting network’s performance when there are the data to transmitted
  • Requires more maintenance as there are multiple Wireless Access Points
• Protocols Sets of rules that define how devices can Communicate, TCP/IP and 4 Layers of transfer-transport data.
• TCP, Application. Transport. A link
• Application, Uses data are identified - HTTP(browsing the internet) - FTP(Transferring files).

Transfer data protocol

• Transport Data into broken packets • Sequence Number TTL added • Network IP Adders Senders ip address destination ip address • Link players Mac address Sender Mac Addres and location

Why Users Layers?

•A Layer is shelf content is compatible the system with another , A Layer can be edit to others.

Protocols

• Protocols define rules for communication
• HTTP (Hypertext Markup Language)
  • Set of rules data is exchanged to access internet
  • Standard uses system and not secure
• HTTPS (Hypertext Markup Language Secure)
  • Set of rules which outlines how secure data is exchanged to access internet
  • Notice is pad locked near URL, Data is protected and encrypted

FTP

• Rules outline used with the servers when users connect data with encrypted
• Email Protocol
• SMTP roles are from PC and Mail Server protocol. Accesses
• Emails and devices sync each other

Logic Gates

• Logic gates are transistors that affect data as it passes through
• 3 Main Gates: AND, OR, NOT they can be represented in expression.
• Not: output is always the opposite of the input

Logic Gates Diagrams

• The statement always begins with the output result to right and left

Logic gates (Examples)

• The output to have each column and gates has a specific result of what do you call to put for each
• Update the Truth table easy mix up one or check it and do double to make sure its correct make mistake

Systems Software

• Operating systems give the interface helps the user work device complex without seeing process to use.

Types of Systems

• Interface is easy beginners or commands while less task . It's more takes main
• Memory than Cli

Management Systems

• User Management Administrator manage computers it gives created user, delete, audit data user create.Access levels level to new users

Types of management in Systems

File Data manage system sort the easy work the storage.

What are peripheral systems?

• Systems device hardware connect computer such can monitor camera .Drivers are a program

Development in It

Discuss advantages of ethics as: such as Ethics, Environmental, Cultural, Data laws , Stakes holder Space each comment

Compressions

• achives lossy compressions while some data has been removed in place permenatly achieves higher compressions • If want transport it easier for images and take the last storage number to detect the difference which would unimportant

LossLess

• Some files be better and return original for some
• Example " Text email and financial records. if there's a small image take up storage"

Example of Lossy and Lossless Files

JPEG is good principle . Can by colour depth and can is good in streaming is a for Audio and Video. Good

• PDF allows less data and good for text image.

Flow Charts

• Uses symbols to explain program and its works well
• Start /stop used start point, symbol be present Flow diagram • input/outer visual presentation better
• Process device will your interaction example calculation and loading
• Decisions of to either make a some it. which symbol. diagram have to base decide data based with to the the. loop

Flow Charts and Programing

• Pre-School children learn tables which you have create flow diagram, must play tables, to help with diagram, which you must set of number must up times value diagram
• The program

•   The should value value the should of which will.
  

• .

•     The if be decision to when loop
  

• .

Mainability

• The propose is code easily what the main code
• 01 Lines programs provide name
• The that read the their understand 02
  • If someone are variables comment
  • that
• 03 Is and that will is clear to code what parts the of see debugger parts. 04 programs see or is or. .

Maintainability

• Important to do all in the file so its clear and not hard to read The process is to make sure over time a program will easily create It, such as example

Trace Tables

• Test short programs with table and contains are used program