4. Software

Question 1

System software

Answer 1

• provides services that the computer requires
• e.g. utility software, like defragmentation software, antivirus, firewall
• e.g. operating system

Question 2

Application software

Answer 2

• provides services that the user requires
• e.g. word processor, web browser, video editing software

Question 3

Operating system

Answer 3

• software that manages computer hardware
• provides a platform for running application software

Question 4

Functions of the operating system

Answer 4

• providing a user interface
• multitasking
• input and output control
• running software
• memory management
• processor management
• handling interrupts
• providing security
• managing user accounts

Question 5

Managing memory

Answer 5

• keeping track of the status of each memory location
• managing the movement of data to and from RAM
• checks that processes have enough memory located to them
• makes sure two processes don’t try to access the same memory location at once
• manage the transfer of pages between virtual memory and RAM
• allows multitasking

Question 6

Managing peripherals

Answer 6

• allocates data to buffers
• transmits data to hardware
• receives data from hardware

Question 7

How interrupts work

Answer 7

• key press generates the interrupt
• interrupt given a priority
• interrupt is sent to CPU
• interrupt is placed in a queue
• CPU finishes current FDE cycle for program
• CPU checks interrupt priority queue
• if lower priority, CPU runs next FDE cycle for program
• if higher priority, processor stores current process/registers on stack
• CPU stops current task to check the queue/service the interrupt
• …using an interrupt service routine (ISR)
• ISR handles/resolves interrupt
• if there is another higher priority interrupt then repeat
• (otherwise) CPU retrieves content of stack/registers

Question 8

Examples of hardware interrupts

Answer 8

• moving the mouse
• clicking a mouse button
• plugging in a device
• paper jam in printer
• printer out of paper

Question 9

Examples of software interrupts

Answer 9

• division by zero
• two processes accessing the same memory location
• null value

Question 10

Purpose of firmware

Answer 10

• permanently store instructions (in ROM)
• store instructions to start up the computer
• provides the operating system with a platform to run on

Question 11

Examples of firmware

Answer 11

• bootstrap
• bootloader
• BIOS

Question 12

Low-level language

Answer 12

• close to the language processed by computers
• may use mnemonics
• an example is assembly language/machine code

Question 13

Advantages of low-level languages

Answer 13

• does not need a compiler/interpreter
• can directly manipulate hardware
• no requirement for program to be portable
• program more memory efficient
• quicker to execute
• can use specialised hardware

Question 14

High-level language

Answer 14

• uses English-like statements
• needs to be converted into machine code
• …using a translator
• portable
• one line of code can perform multiple commands

Question 15

How compilers report errors

Answer 15

• creates an error report after trying to compile
• …displaying all errors in the code
• …that require correction before execution can take place

Question 16

IDE

Answer 16

software designed to make writing high-level languages more efficient

Question 17

Functions of IDEs

Answer 17

• code editors
• run-time environment
• built-in compiler
• built-in interpreter
• error diagnostics
• auto-completion
• auto-correction
• prettyprinting