Unit 4.1 - types of software and interrupts Flashcards
What is software?
All computer programs which can be split into two broad groups : system or application. All software is stored on secondary storage devices.
Used for controlling the operation of a computer or processing electronic data.
What is system software?
A type of software/set of programs used to manage hardware devices and application software. Manages, maintains and runs the computer itself and allows it to communicate with other devices. There are 2 types : utility systems and operating systems.
For computer.
What is application software?
A set of programs that allow the user to perform an activity such as creating a document or editing a picture. Sometimes called productivity software.
E.g. word processing software (Word), spreadsheet software (Excel), etc.
For user.
What is an operating system?
A type of system software that manages the computer’s hardware & software and how resources are used (e.g. which programs are processed by the CPU, where data is stored in RAM, etc). Allows application software to run.
They also provide user interface which gives a means of communication between users and computer systems.
E.g. Windows, MacOs
What is utility software?
A type of system software used to perform maintenance and optimization tasks, like compression, backup, anti-malware, defragmentation and encryption software.
Keeps computer safe and running efficiently. Provides useful tools to manage files/applications.
What is user interface + types?
A mix of software with input & output devices to allow users to communicate with computer systems.
4 types:
1. GUI - graphical user interface; using icons, menus and pointers. E.g. Windows
+ easy to navigate, intuitive
- slower than CLI for advanced users, user more RAM than it needs, requires more space on HDD
2. CLI - command line interface; where commands are typed. E.g. DOS
+ highly efficient for advanced users, little HDD storage needed, little memory required
- confusing for noobs, lots of commands to learn, easy to make mistakes
3. Dialogue based interface - using voice commands
+ intuitive, hands free, no typing
- not very reliable,
4. Menu - single option chosen at each stage. E.g. Smartphone/Netflix.
+ intuitive, easy to navigate, little processing power
- long navigation process, may be annoying
What is the effect of providing an interface?
Allows the user to issue commands and run programs, called human computer interaction.
What are the functions of an operating system?
- File management - OS is responsible for allocating space on secondary storage devices and managing creation and deletion of file
- Memory management - OS handles loading programs from hard drive to RAM, and sometimes manages virtual memory. Controls the allocation of RAM to individual programs. Also makes sure that one program cannot access the memory of another program
- Processor management - the process of controlling and allocating a computer’s CPU resources to various tasks or processes running on a system
- Device management - OS manages all hardware or virtual devices of a computer. This includes installing device drivers and keeping them up-to-date.
- Provides security system - the security includes : protects it against unauthorized access over the Internet, ensures that user cannot access files without permission (if needed)
- Provides user interface
- Handling interrupts - receives and processes requests from peripheral devices
- Provides platform to run applications - OS allows user to start/stop programs and install/uninstall them.
- Manages multi-tasking - OS is responsible for switching between running tasks and allocating each some of the CPU’s processing time (scheduling). Programs are not actually running at the same time, but the switches between them are so fast that it seems like they are.
- Managing user accounts - allows multiple user to log into the same computer.
What are device drivers?
System software which OS uses to communicate with peripheral devices such as printers - it translates OS instructions into specific commands that the hardware can understand (the same type of hardware devices such as printers have different components/architecture)
What is firmware?
Software stored in ROM that allows a computer system to start up/boot and access its hardware/secondary storage devices and operating system. Also known as bootloader or BIOS (in PCs).
Define boot
Start up a computer system
Steps of booting computer
- Firmware must be loaded (it is stored on hardware)
- Operating system is loaded by firmware
- All other software is loaded by operating system (application + utility system)
- User interacts with application software
What is an interrupt?
A signal sent from hardware/software to the CPU in order to request CPU attention. Interrupts always have a higher priority than normal programs.
What is an ISR?
An interrupt service routine is a series of events run by the OS after receiving an interrupt, such as prioritizing tasks and executing interrupt actions as needed.
How are interrupts handled?
When the CPU receives an interrupt, the current values held in registers are copied into a data structure in memory called a stack. These are pushed onto the stack in a stack frame, saving them for later retrieval. Once the interrupt is executed, the frame is popped of the top of the stack. This allows us to load the original values back into the registers and continue executing the program where we left off.
Examples of interrupts
- Hardware - power supply failure, power/reset button pressed, power-down command
- Software - illegal instruction encountered, arithmetic overflow, new login request, division by 0
- User - moving mouse, clicking icon to open new program, keyboard presses
- Timer - screen recording, data-logging program reading sensor
- Input/output device - buffer nearly empty, signal completion of data transfer, printer ink supply notification
What is syntax?
The structure of language statements in a computer program
What is application software run on?
Application software -> operating system -. firmware -> hardware
