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Topic 3, Utility Software - collection of small specialised programs that…
Topic 3
Short term working memory - holds information currently using in CPU.
CPU has 3 buses address bus, data bus and control bus. They work together to transfer data between CPU, main memory and input/output
Address bus - Holds address and memory location. Control bus carries the signal. Data bus transfers the information/data.
Control unit fetches program instructions from main memory
Clock synchronises actions. Each tick triggers CPU to take perform an action. 1 hertz = 1 cycle. Typically have 3 gigahertz. higher clock speed more instructions can be executed
ALU perfoms logical and arithmetic operations
Registers provide direct access storage to information. Some have specific functions
Programmable computers have: A main memory - where program instructions and data are loaded
CPU - to decode-execute -fetch information
Input and Output
To fetch an instruction the CPU puts memory address of next instruction on address bus. Decode instruction - The Control Unit (CU) then sends a read signal along the control bus. Execute instruction - Information then transferred from RAM via data bus.
Secondary storage is needed is non volatile and can hold permanent information. Program has to be transferred to CPU to be accessed has large storage capacity. Typically around 4 TB
Types of secondary storage are Optical storage - ie CD Rom, DVD. Magnetic storage -hard disk drives, magnetic tape drives. Solid State Storage - Mobile phones, smart watches
Stored program concept designed by Alan Turing and John Von Newman in the 1940's
Various storage locations to hold information or programs
RAM - random access memory where information can be read from and written to in any order. Generally between 4 and 32GB.
Primary storage is accessible to CPU
Utility Software - collection of small specialised programs that complete task
Data compression software - purpose to reduce size of data taking up less room on secondary storage
File Repair Software - purpose to recover and repair data from corrupted files by scanning and extracting as much data as possible
Disk defragmentation software - purpose to speed up access to files as it rearranges files into blocks so stored in adjoining blocks
Back up software - purpose to keep copy of files incase of loss or corruption being stored on a separate device
Anti-malware software - purpose to protect computer system from worms, malware, viruses and spyware. Looks for patterns from database and if locates one quarantines it
Embedded systems
Components - Long life battery, sensors, low powered microcontroller that contains CPU, actuators to convert output commands
Examples are washing machines that regulates amount of water required per wash, anti-lock braking system to stop care from skidding
Features - limited memory and processing, low power consumption, low maintenance, wireless connectivity, small, single purpose, customised hardware/software,
Robust Software - a program which can handle unexpected actions without crashing
code vulnerabilities - hidden weaknesses. Some programming languages like C can access computer memory directly allowing hackers to create a back door. To make more robust audit regularly keeping a trail, use good programming practices
Code Reviews - to find inefficient code, identify potential vulnerabilities, check software adheres to good standard.
Audit Trails - helps improve accountability by tracking who made changes and when. Code can then be rolled back where needed. Version control software is often used alongside as creates database of changes to code
Programming languages - used to write code using 2 categories high- level and low-level.
High level - Java and python use human words such as print, if and return. Focus on program logic and are problem orientated. Have libraries of ready made functions making it easier to wrote code. Program must be translated by CPU before being executed
low level - uses binary instructions 0s and 1s. Very difficult to write and debug as massive amounts of code. This makes difficult to debug or audit. Can only be run on certain computers with different CPU and interacts directly with hardware enabling memory to be used efficiently
Operating system - is interface between hardware and software ie windows, apple IOS, Linux
Main tasks - File management, process management, user management, peripheral management
File management - Responsible for keeping track of files. Root directory at top feeds into nodes and branches, directories and sub directories
User Management - Provides interface to use computer such as Windows, Apple IOS (GUI). It accesses control using passwords or logins, and gives permissions for users to read, write, execute or delete files.
Peripheral management - Is an additional item like a keyboard, printer, graphics card or mouse. The OS uses drivers to keep these up to date and working correctly