16 System software

Question 1

DMA Direct Memory Access controller

Answer 1

Allows hardware to access RAM independent of CPU to free up the CPU to carry other tasks while slow I/O operations take place.

Question 2

Kernel

Answer 2

Part of the OS responsible for communication between hardware, software and memory. Responsible for process management, memory management, interrupt handling and I/O file communication.

Question 3

Low Level Scheduling

Answer 3

a method where a process is assigned to a task based on priority level.

Question 4

Process Control Block

Answer 4

data structure that contains all the data needed for a processor to run. ex: current process state *ready, running, blocked), process privileges, register values, priority, amount of CPU time needed, process ID.

Question 5

Pages

Answer 5

fixed sized logical memory blocks

Question 6

frames

Answer 6

fixed size physical memory blocks

Question 7

virtual memory

Answer 7

type of paging that gives the illusion of unlimited memory by swapping data between RAM and swap space.

Question 8

Disk Thrashing

Answer 8

problem resulting from use of virtual memory where excessive swapping leads to high rate of disk read and write head movements therefore reducing processing speed.

Question 9

Lexical analysis

Answer 9

the first stage in the process of compilation where all unnecessary characters such as white space and comments are removed from program.

Question 10

Syntax analysis

Answer 10

second stage in compilation process where output from lexical stage is checked for grammatical errors.

Question 11

Code generation

Answer 11

third stage in compilation process where the object program is produced.

Question 12

Optimisation

Answer 12

forth stage of compilation process where an efficient program is created.