Operating Systems Flashcards
What is software?
- A collection of electronically stored instructions
(i. e., a program) that allows one to interact with a computer
What are the two categories software can be categorized into?
- Application Software
2. System Software
What is application software?
- A computer program designed to help people perform
an activity
What is system software?
- A type of computer program that is designed to run a computer’s hardware and application programs.
Examples of application software
- Office suites (e.g., Office 2016)
- Image editors (e.g., GIMP)
- Web browsers (e.g., Chrome)
- Video conferencing (e.g., Zoom, Skype)
- Acrobat reader …
Examples of system software
- Operating systems (e.g., macOS, Windows, Linux)
2. Anti-malware (e.g., Trend Micro Anti-Virus )
Three Roles of an Operating System
1) Process management
- Manage numerous,
concurrently running programs
2) Memory management
- Allocate and track efficiently
3) Device management
- Grant and share access to computer’s hardware
Recall that a process is a program in ———
exceution
How many processes can a CPU process at one time?
-one
Kernel
- Core of a computer’s operating system and generally has complete control over everything in the system.
GUI
Graphic User Interface: Type of user interface through which users interact with electronic devices via visual indicator representations (icons, mouses, menus)
CMD: Command for Microsoft windows
- Used to execute entered commands and perform advanced administrative functions.
What are the five stages of processing?
- New
- Ready
- Waiting
- Running
- Terminated
- New - State of Processing
- New process that has been created but has not yet been admitted by the OS for its execution.
- A new process is not loaded into the main memory, but its process control block (PCB) has been created
- Ready-State of Processing
- A process that is prepared to execute when given the opportunity by the OS.
- Waiting-/Blocked State of Processing
- A process cannot continue executing until some event occurs like for example, the completion of an input-output operation.
- Running-State of Processing
- The process is currently being executed.
- Terminated- State of Processing
- A process or job that has been released by the OS, either because it is completed or is aborted for some issue.
What can cause a process to move into a waiting state?
- If it needs more data or information from the user in order to complete it
- if it needs to wait for a resource, such as waiting for user input, or waiting for a file to become available.
What is data structure?
- Used by the OS to manage information
about a process
What current values are managed by the data structure?
1) The program counter (where the execution should
start/resume)
2) All CPU registers for the process (CPU state)
3) base and bound registers or page-map tables (memory management info, see later)
4) Accounting information (owner, priority, files and network connections open)
What does each state contain?
- Each state contains a list of PCBs, one for each process in that state
What is a new PCB first created?
- When the process is first created and persists until the process terminates
What happens to the corresponding PCB when the process moves from one state to another?
- Moves from one state list in the operating system
What happens each time a process is moved to the running state?
- Register values for the currently running process
are stored into its PCB - Its PCB is moved to the list of the state into which it goes
- Register values of the new process moving into the running state are loaded into the CPU
What is a context switch?
- Exchange of register information
What is used to determine which processes move from ready to run?
- CPU Scheduling Algorithms