Chapter 1: Introduction, Vocabulary

sectors

Look at diagram pg. 468 ch 10. Figure 10.1; disk surface logically divided into tracks, subdivided into sectors

tracks

Look at diagram pg. 468 ch 10. Figure 10.1; disk surface logically divided into tracks, subdivided into sectors

Protection

Within the system, like antivirus software

WORM

Write Once Read Many

jobs

code and data

kernel mode

-In Kernel mode, the executing code has complete and unrestricted access to the underlying hardware. -It can execute any CPU instruction and reference any memory address. -Kernel mode is generally reserved for the lowest-level, most trusted functions of the operating system

interrupt driven (hardware and software)

-hardware interrupt by one of the devices -software interrupt (exception/trap): software error (e.g. division by zero), request for OS service, infinite loop

bootstrap program

-loaded at power-up or reboot -typically stored in ROM or EPROM -generally known as firmware -initializes all aspects of system -Loads operating system kernel and starts execution

timesharing (multitasking)

-logical extension of multiprogramming -CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing -response time: <1 second

user mode

-non-privileged mode in which each process starts out -one of two distinct execution modes for the CPU in Linux

multiprogramming (batch system)

-organizes jobs so CPU always has one to execute -subset of total jobs in system is kept in memory -one job selected and run via job scheduling -when it has to wait (i.e. for I/O), OS switches to another job

firmware

-permanent software programmed into ROM or EPROM -in between hardware and software

timesharing system

CPU switches jobs so frequently that users can interact with each job while it is running

control program

OS is a control program; Controls execution of programs to prevent errors and improper use of the computer

resource allocator

OS is a resource allocator; Decides between conflicting requests for efficient and fair resource use, manages all resources

Security

Outside the system, like logins and stuff

RW

Read/Write

file

Resource for storing information

servers

a computer or computer program that manages access to a centralized resource or service in a network.

Binary search tree

a data structure that can be used to represent data hierarchically. Requires an ordering between the parent's two children in which left child <=right child

workstation

a desktop computer terminal, typically networked and more powerful than a personal computer.

polling

a specific type of I/O interrupt that notifies the part of the computer containing the I/O interface that a device is ready to be read or otherwise handled but does not indicate which device.

Bitmap

a string of n binary digits that can be used to represent the status of n items. Pg. 34 has example

dual-mode

allows OS to protect itself and other system components; user mode and kernel mode

virtual memory

allows execution of processes not completely in memory

vectored

an alternative to a polled interrupt , which requires that the interrupt handler poll or send a signal to each device in turn in order to find out which one sent the interrupt request.

multiprocessors (parallel systems)

computer with multiple CPU's -increased throughput (amt of material passing through the system) -Economy of scale (shares peripherals, mass storage, power) -increased reliability, graceful degradation (if one dies others take work)

interrupt vector

contains the addresses of all the service routines

caching

copying information into faster storage system; main memory can be viewed as a cache for secondary storage

nonvolatile

does not lose its contents when the power to the device is removed

asymmetric multiprocessing

each processor is assigned to a specific task

symmetric multiprocessing

each processor performs all tasks

solid-state disks

faster than hard disks, nonvolatile

device driver

for each device controller to manage I/O, Provides uniform interface between controller and kernel

swapping

if processes don't fit in memory, swapping moves them in and out

privileged

instructions only executable in kernel mode

kernel

one program running at all times on a computer

disk controllers

operates the disk-drive hardware to carry out the command; determines the logical interaction between device and computer

process

program executing in memory

mode bit

provided by hardware -provides ability to distinguish when system is running user code or kernel code -system call changes mode to kernel, return from call resets it to user

trap/exception

software-generated interrupt caused either by an error or a user request

virtual machine manager (VMM)

the VMM has more privileges than user processes but fewer than the kernel. It needs that level of privilege so it can create and manage virtual machines, changing the CPU state to do so.

CPU scheduling

the basis of multiprogrammed operating systems. By switching the CPU among processes, the operating system can make the computer more productive

random access

the process of transferring information to or from memory in which every memory location can be accessed directly rather than being accessed in a fixed sequence.

multiprogramming

the running of two or more programs or sequences of instructions simultaneously by a computer with more than one central processor

volatile

volatile storage loses its contents when the power to the device is removed