Flashcards
Operating system structures
Cards in this deck (16)
- 1What is the overall purpose of an operating system?The operating system interacts with a computer's hardware on a basic level, transmitting your commands into language the hardware can interpret. The OS acts as a platform for all other applications on your machine.
- 2How can the operating system make several programs execute seemingly "at the same time"?Multiprogramming and multitasking.
- 3What is the difference between a program and a process?Program - set of human readable instructions
Process - A program loaded into memory and executing or waiting - 4Whats the purpose of the PCB?Contains information to manage a particular process. Information about its state, id, registers etc
- 5What are some of the states that a process can be in?New, ready, running, terminated,wait
- 6What is the overall purpose of the system call concept?So programs can request service from the Kernel. This may include services like accessing hard disk, executing and creating new processes
- 7A common pattern when using system calls is for the caller to first allocate storage and then pass a pointer to this storage to the system call - why?If we get data in return that is too large for the registers it should be placed ??
- Kernel: not safe, the user can access data there
- User should allocate memory in its own adress space and pass the pointer to this adress. Safe! - 8MultiprogrammingOne job is chosen for execution. When it has to wait for I/O the OS switches to another job
- 9Multitaskingexpansion of multiprogramming. A timer is set to enforce interrupts
- 10Difference between interrupts and exceptionsinterrupts are used to handle external events (serial ports, keyboard) and exceptions are used to handle instruction faults, (division by zero, undefined opcode). Or traps - software generated interrupts
- 11Draw kernel layout
- 12What is the kernel?a computer program that is the core of a computer's operating system, with complete control over everything in the system. The core task is to start the system, manage resource allocation communicate with the hardware. Usually it works as a layer between the computer hardware and processes.
- 13What is the command interpreter?Understands and executes commands that are entered by a human or a program
- 14What is the Shell?adds useful features that makes it easier to enter commands, ex;
* pipes * I/O redirection - 15What is the API?Application programming interface
= set of functions that are available to an application programer. (tex Java API) - 16System call interfaceInterrupts functions calls in the API and invokes system calls.
Example: standard C library
If you call printf() in C the library invokes the write system call.
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- Operating systems Flashcards on Operating system structures , created by Emma Tysk on 13/03/2017.
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- Emma Tysk
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