Week 2: Concepts and Structures Flashcards
What is a process?
- A process is an instance of a program that is executed
- A process is an active entity
What are interrupts?
- The process of the processor stopping what it’s doing and executes a specific interrupt routine
What part of the system is responsible for the generation of the interrupts at regular intervals?
The clock
What are the regular clock interrupts used for?
To transfer from a running process back to the operating system
the OS can then save the current process information and swap to another process (new or old)
What is privileged mode?
It is when the operating system has access to all instructions and resources
What is user mode?
It is when the operating system has access to a limited amount of instructions and resources
What is a file?
A collection of information
What is a folder?
A special type of file that holds the names of the files and groups them together
What is the purpose of System Calls?
To provide an interface between a process and the operating system
What are the services of System calls?
- Process control: create, terminate, wait
- File manipulation: create, delete, open, close, read, write
- Device manipulation: allocate, deallocate, read, write
- Information maintenance: set/get date/time, user info
- Communications: create/delete connection, send, receive
What is the layered structure of the operating system?
It is a structure that has a number of layers that can only invoke operations on the lower layers. These layers are:
0. Hardware
1. CPU scheduling
2. Memory management
3. Device drivers
4. Buffering for I/O devices
5. User programs
What are the main device types?
Block devices: Read and write data in blocks
Character devices: Read and write data in single bytes/characters
What is CLI foreground?
The instance when the screen is locked until a command finishes
What is CLI background?
The instance when the user can type while a command is running
