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