Operating System 2

Ability to run multiple programs.

Increases CPU utilization.

Uses input devices to receive instructions and output devices to display results.

Users can interact with each program while it is running.

If there are no processes to execute, no I/O devices to service, and no users to whom to respond, an operating system will sit quietly, waiting for something to happen.

is a signal that specifies the occurrence of a particular event.

Provides distinction between the execution of operating-system code and user-defined code.

Allows OS to protect itself and other system components.

execute in behalf of the user app.

is when a user application requests service from the OS via a system call.

Allows OS to maintain control over the CPU by not allowing a user program to get stuck in an infinite loop or to fail to call system services and never return control to the OS.

Set to interrupt the computer after a specified period of time.

Prevents a user program from running too long and works hand in hand with a counter.

Passive entity, like the contents of a file stored on disk.

Active entity; program in execution.

Needs resources to accomplish its task: CPU time, Memory, files, I/O devices.

Has one program counter, specifying the location of the next instruction to execute.

Executed sequentially, one instruction of a process after the another.

Has multiple program counters.

_____ is generally the only large storage device that the CPU is able to address and access directly.

Determines what is in memory.

Optimizes CPU utilization and computer response to users.

provides a uniform, logical view of information storage.

Defines a logical storage unit called file.

One of the most visible components of an operating system.

determines which user may access a file and how that user may access it.

Computer systems provides secondary storage to backup main memory (use of disk).

Programs are stored on a disk until loaded into memory.

As it is used, it is copied to a faster storage system, the ___ for temporary basis.

Information is normally kept in main memory.

If a piece of information is need, the ___ is check first.

storing temporarily while transferring.

storing to faster storage.

overlapping of output of one job with input of other jobs.

Drivers for specific hardware device.

Any mechanism for controlling access of processes or users to resources defined by the OS.

Defense of the system against internal and external attacks.

One purpose of OS is to hide peculiarities of hardware devices from the user.