운영체제 Operating System 개념

xdots 2024. 1. 28. 20:18

BIOS (Basic Input/Output System) BIOS finds the configured primary bootable device (computer's hard disk) and loads and executes the initial bootstrap program from the master boot record (MBR). The MBR is the first sector of the hard disk, with zero as its offset (sectors counting starts at zero), MBR파일 형식
CMOS (complementary metal–oxide–semiconductor)
UEFI (Unified Extensible Firmware Interface), UEFI 모드: GPT(GUID Partition Table)파일 형식

부트스트랩 로더(bootstrap loader)의 준말로 컴퓨터를 사용자가 사용할 수 있도록 디스크나 플래시에 저장된 운영체제를 읽어 주기억장치에 적재해주는 프로그램
LILO(LInux LOader)
GRUB(GRand Unified Boot loader)
NTLDR(NT LoaDeR)
ARMBOOT
BOOTLDR
REDBOOT
U-BOOT(Universal BOOTloader)

Kernel
Bootstrap Program
System Call
Caching
Multiprocessor System
Multiprogramming
Dual Mode – User Mode, Kernel Mode
Process
Process Control Block (PCB)
Threads
CPU Scheduling
Buffering & Spooling
Deadlock: Two or more processes are waiting indefinitely for an event that can be caused by only one of the waiting processes (most OSes do not prevent or deal with deadlocks)
Semaphore: Synchronization tool that does not require busy waiting
Transition Look-aside Buffer (TLB): is a CPU cache that memory management hardware uses to improve virtual address translation speed
Timesharing – CPU switches jobs so frequently that each user can interact with each job while it is running (interactive computing)
Dual-mode operation allows OS to protect itself and other system components – User mode and kernel mode
◦ Some instructions are only executable in kernel mode, these are privileged
Single-threaded processes have one program counter, multi-threaded processes have one PC per thread
Protection – mechanism for controlling access of processes or users to resources defined by the OS
Security – defense of a system against attacks
User IDs (UID), one per user, and Group IDs, determine which users and groups of users have which privileges