Basic Terms Flashcards
What is the purpose of an OS?
Simplify the interface to a computer’s underlying hardware and to manage a system’s resources so they are used in a equitable and safe manner.
Name a few types of OSes.
- Mainframe
- Sever
- Multiprocessor
- Personal Computer
- Handheld Computer
- Sensor Node
What do OSes manage?
- Users
- Resources
- Execution codes
Name the elements of a typical OS.
- User-level interfaces
- Validation components
- Scheduler
- Components that manage memory
- Virtual file system
- Device drivers
- Tracking tables for system executions
How do OSes ensure system reliability?
They protect sensitive code/resources from casual access.
What are the layers of the OSI model?
Application Presentation Session Transport Network Data Link Physical
Where are user codes stored in memory?
The user space
Where are system codes stored in memory?
The kernel space
What are the purpose of traps?
Traps ensure that attempts to access the kernel space/privileged instructions do the following:
- Reset the operating mode from the user (unpriv.) to priv.
- Validate the attempts to access these resources.
- Carry out/reject the access-related requests.
What is a system call?
A routine that explicitly trap to the kernel.
What are the advantages / disadvantages of a monolithic kernel?
Adv. - better performance
Dis. - maintainability; difficulty of validating kernel operation, including kernel security
What are the advantages / disadvantages of a microkernel?
Adv.- maintainability; improved support for validating kernel operation.
Dis.- lower performance, due to increased need for context switching to access different functionality.
What is a register for an I/O device?
These are dedicated memory locations whose bits monitor and control device operation.
What items can registers also control?
Processor operation
Traps
Virtual Memory
What two ways are APIs codified?
De facto- determined mostly by features provided in widely used implementation.
POSIX- an IEEE standardization of Unix features
