Questions and Answers
Which of the following is true about BIOS?
It is firmware stored in ROM
What is the purpose of a system call?
To request a kernel to perform a service
What is the difference between volatile and persistent storage devices?
Volatile storage devices retain data even when power is off, while persistent storage devices do not
Study Notes
Introduction to Operating Systems and System Calls
- An operating system (OS) manages computer hardware and application software, and provides interfaces for both to access hardware and run programs.
- OS manages memory/disk allocation, process scheduling, and peripherals control.
- There are two types of storage devices: volatile (registers, cache, RAM) and persistent (HDD, SSD, USB, optical drives).
- BIOS is firmware stored in Read-Only Memory (ROM) chip.
- CPU instruction consists of two parts: Operation Code and Operands.
- There are two CPU execution modes: Kernel mode and User mode.
- Modern computers implement CPU execution modes through protection rings that provide different privilege levels represented as numbers.
- A Dual-Mode OS uses two modes of CPU operations: Kernel/Privileged/System mode and User/Non-Privileged mode.
- Linux programs are stored in /bin/ or /sbin directories, and can be run by typing the name of the program if the program path is included in the PATH Variable.
- Every process in Linux is provided with three open streams (files).
- Two ways to send notifications between CPU and I/O devices are Polling and Interrupts.
- A system call is a mechanism by which a request is made to a kernel to perform a service, and is generally invoked through wrapper functions in glibc library.
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