What is:
Application software
runs on the operating system and provides the services that the user requires
What is a:
System software
Programs needed for the computer to function, includes operating system, utilities, library routines and programming language tranlators
What is:
OS
Operating system, a group of programs essential for managing computer’s resources, which manages:
* Multitask
* peripherals and drivers
* files
* user accounts
* handling interrupts
* provides an interface
* provides a platform for running applications
* memory
* provides system security
How does an:
OS system manage multitasking
- Circular queue
- Each component of the queue has its allocated time-slice
- in this time-slice the program is ran
- When the time-slice is over the task goes to the back of the queue
- Time-slice is short
How does the:
OS manage peripherals and drivers
- They communicate to the OS and are connected to it that way
- Drivers is software used to provide an interface for the hardware device
How does the:
OS manage files
- Allows users to create, delete, move, save and copy files, or allocat them to folders. It can search for files, restore deleted files, free up space for new files and modify access rights
How does the:
OS manage user accounts
- Different users with own user name and password management
- can be different levels of access per account
- Monitors login activity and log out users after set periods of inactivity
How does the:
OS handle interrupts
Calls ISR (Interrupt service routine) and determines how to handle each interrupt
What are:
Interrupts
- signals from a software program or hardware device to the CPU
- Software interrupts when an application terminates or requests resources from the OS, or an error occurs such as division by 0
- hardware interrupts can also happen if USB devices are plugged in and more, e.g. keyboard or mouse moved
How does the:
OS provide an interface
- Through buttons, keyboards, touchscreens, mice and more
usually has a Graphical User Interface (GUI)
or WIMP (windows, icons, menus, pointer) interface
How does the:
OS provide a platform for running applications
OS will manage the process by allocating memory space for the software and control its access to data or devices
How does:
OS manage memory
moves programs and files between memory and storage if virtual memory is required
How does the:
OS provide system security
- Controls user access to prevent users from accessing files or folders they should not have access to
- Seurity updates are downloaded to help fix bugs and improve security against malware
- Can encrypte files on hard disk
What is the:
Bootloader
- small peice of software
- responsible for starting up a computer
- held in ROM
- non-volatile, and loads OS into RAM
What is a:
High-level language
- Has syntax and structure similar to english
- Can be understood by humans
- E.g. python, hardware independent, and can run on any system
- Must be compiled or interpreted before run into object code which can be read and ran by the computer
What is a:
Low level language
- Contains assembly langauge
- Hard to read
- Executes quckly and takes less memory as translating it is easier than translating equivalent high-level language
What is:
Machine code
- binary instructions produced by compiler or interpreter
- Each device might have different machine code, so it may not work on different devices
What are the different:
Translators
- Compilers
- Interpreter
- Assembler
What is a:
Compiler
- Translator which translates a high-level language in 1 go to machine code
- faster than interpreted code as it is already in machine code
- produces an executable file so the orignal file does not need to be compiled again
- no need for compiler when object code is run
- After compilation an error report is present for the whole code
- e.g. C#
What is an:
Interpreter
- Translates and executes a line of high-level language program at the time
- takes more time to execute as each instruction is translated before it is run
- interpreter must be installed to run the program
- interpretor stops execution when an error is found, good for developing a program
- e.g. python
What is an:
Assembler
- Converts assembly language into binary
- relatively easy, as an assembly language instruction translates into a single instruction
- eg. LDA#17 is load value 17 into accumulator
What is:
IDE
- integrated development environmnet
- used to enter and edit source code, compile programs and have debugging features
What are the uses of:
IDE
- Error diagnostics - highlights errors
- Breakpoints can pause the program at a certain point to check values of variables
- Runtime environment - allows program to be run
- Translators - compiler or interpreter is used
- Code editors - programmers can write code, conains auto-correct and completion as well as formatting
