Download Authentication is the process of determining whether someone or

專業英文導讀
Chapter 7
Key Terms
Key Term
Definition
Page #
Authentication
Verification of the sender of a message.
211
Authentication is the process of determining
whether someone or something is, in fact, who
or what it is declared to be.
Batch operating system
The operating system used in early computers, 195
in which jobs were grouped before being
served.
Batch operating system was designed in the
1950s to control mainframe computers.
Bootstrap
The process in which the operating system is 194
loaded into main memory when the computer
is turned on.
A very small section of memory is made of
ROM and holds a small program called the
bootstrap program.
Circular waiting
A condition in an operating system in which all 207
processes and resources involved form a loop.
Circular waiting implies the hold and wait
condition. Therefore, these conditions are not
completely independent.
Deadlock
A situation in which the resources needed by 206
one job to finish its task are held by other jobs.
Deadlock
is
a
common
in multiprocessing systems, parallel
problem
computing and distributed systems, where
software and hardware locks are used to handle
shared resources and implement process
synchronization.
Demand paging
A memory allocation method in which a 201
segment of a program is loaded into memory
only when it is needed.
I demand paging the program is divided into
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專業英文導讀
pages, but the pages can be loaded into
memory one by one, executed, and replaced by
another page.
Demand paging
segmentation
and A memory allocation method in which a page 201
or a segment of a program is loaded into
memory only when it is needed.
Demand paging and segmentation can be
combined to further improve the efficiency of
the system.
Demand segmentation
A memory allocation method in which a 201
segment of a program is loaded into memory
only when it is needed.
In demand segmentation, the program is
divided into segments that match the
programmer’s view.
Device manger
A component of an operating system that 208
controls access to the input/output devices.
The device manager, or input/output manager,
is responsible for access to input/output
devices.
Distributed system
An operating system that controls resources 201
located in computers at different sites.
Distributed systems are the study of the
communication and coordination patterns of
components found in networked computers.
Frame
In paging, memory is divided into equally sized 200
sections called frames.
In paging, memory is divided into equally sized
sections called frames.
Graphical
interface(GUI)
user A user interface that defines icon and 197
operations on icons.
Designing the visual composition and temporal
behavior of a GUI is an important part
of software applicationprogramming in the area
of human-computer interaction.
Hold state
The state of a job that is waiting to be loaded 203
into memory.
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A program becomes a job when selected by the
operating system and brought to the hold state.
Hardware
abstraction A hardware abstraction layer (HAL) is 212
an abstraction layer, implemented in software,
layer(HAL)
between
the
physical hardware of
a computer and the software that runs on that
computer.
The NetBSD operating system is widely known
as having a clean hardware abstraction layer
which allows it to be highly portable.
Job
A Program becomes a job when it is selected 202
for execution.
A program is a job from the moment it is
selected for execution until it has finished
funning and becomes a program again.
Job scheduler
A scheduler that selects a job for processing 204
from a queue of jobs waiting to be moved to
memory.
The job scheduler moves a job from the hold
state to the ready state or from the running state
to the terminated state.
Kernel
The main part of an operating system.
210
The kernel is the heart of the UNIX system.
Linux
An operating system developed by Linus 211
Torvalds to make UNIX more efficient when
run in an Intel microprocessor.
In 1991, Linus Torvalds, a Finish student at the
University of Helsinki at the time, developed a
new operating system that is known today as
Linux.
Memory management
The component of the operating system that 197
controls the use of main memory.
One of the responsibilities of a modern
computer system is memory management.
Microsoft disk operating The operating system based on DOS and 211
developed by Microsoft.
system
In the 1980s Microsoft, under the leadership of
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專業英文導讀
Dave Cutler, started development of a new
single-user
MS-DOS.
Monoprogramming
operating
system
to
replace
The technique that allows only one program to 197
be on memory at a time.
Monoprogramming belongs to the past, but
it is worth mentioning because it helps us to
understand multiprogramming.
Multiprogramming
The technique that allows more than one 198
program to reside in memory while being
processed.
In multiprogramming, more than one program
is in memory at the same time, and they are
executed concurrently, with the CPU switching
rapidly between the programs.
Mutual exclusion
A condition imposed by an operating system in 207
which only one process can hold a resource.
In computer science, mutual exclusion refers
to the requirement of ensuring that no
two concurrent processes[a] are in their critical
section at the same time; it is a basic
requirement in concurrency control, to
prevent race conditions.
No preemption
A condition in which the operating system 207
cannot temporarily allocate a resource.
No preemption is that resources cannot be
preempted.
Operating system
The software that controls the computing 194
environment and provides an interface to the
user.
An Operating system is complex, so it is
difficult to give a simple universal definition.
Page
One of a number of equally sized sections of 200
program.
Programs are also divided, into equally sized
sections called pages.
paging
A Multiprogramming technique in which 200
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專業英文導讀
memory is divided into equally sized sections
called frames.
Paging improves the efficiency of partitioning.
Parallel system
An operating system with multiple CPUs on 196
the same machine.
The need for more speed and efficiency led to
the design of parallel systems: multiple CPUs
on the same machine.
Partitioning
A technique used in multiprogramming that 199
divides the memory into variable-length
sections.
The first technique used in multiprogramming
is called portioning.
Process
A program in execution.
203
A process is a program in execution.
Process scheduler
An operating system mechanism that 204
dispatches the processes waiting to get access
to the CPU.
The process scheduler moves a process from
one state to another.
Program
A set of instructions.
202
A program is a nonactive set of instructions
stored on disk.
Portability
The quality factor relating to the ease with 211
which a system can be moved to other
hardware environments.
Design goals released by Microsoft are
extensibility,
portability,
reliability,
compatibility and performance.
Process manager
An operating system component that controls 197
the processes.
A modern operating system has at least four
duties: memory manager, process manager,
device manager, and file manager.
Queue
A liner list in which data can only be inserted at 205
one and, called the rear, and deleted from the
other end, called the front.
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專業英文導讀
To handle multiple processes and jobs, the
process manager uses queues.
Ready state
In process management, the state of processing 203
in which the process is waiting to get the
attention of the CPU.
Where there is memory space available to load
the program totally partially, the job moves to
the ready state.
Real-time system
An operating system that is expected to do a 196
tack within specific time constrains.
A real-time system is expected to do a task
within specific time constraint.
Reliability
The quality factor that addresses the confidence 211
or trust in a system’s total operation.
Design goals released by Microsoft are
extensibility,
portability,
reliability,
compatibility and performance.
Resource holding
A condition in which a process holds a resource 207
but cannot use it until all other resources are
available.
Resource Holding is A process is currently
holding at least one resource and requesting
additional resources which are being held by
other processes.
Running state
In process management, a state in which a 203
process is using the CPU.
The process scheduler chooses the processes or
jobs to be executed only at the running state.
Scheduler
A program to move job from one state to 204
another.
Operating system scheduling is the process of
controlling and prioritizing messages sent to a
processor. An internal operating system
program, called the scheduler, performs this
task.
Scheduling
Allocating the resourced of an operating 196
system to different programs and deciding
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which program should use which resource, and
when.
A scheduling system allows one process to use
the CPU while another is waiting for I/O,
thereby making full use of otherwise lost CPU
cycles.
A user interface in some operating systems, 197
such as UNIX.
Shell
In computing, a shell is a user interface for
access to an operating system's services.
Single-user
system
operating An operating system in which only one 196
program can be in memory at a time.
When personal computers were introduced,
there was a need for an operating system for
this new type of computer. During this era,
single-user operating system such as DOS was
introduced.
Software
The application and system program necessary 193
for computer hardware to accomplish a task.
Computer software is divided into two broad
categories: the operating
application programs.
Starvation
system
and
A problem in the operation of an operating 207
system in which processes cannot get access to
the resources they need.
Starvation is the opposite of deadlock.
State diagram
A diagram that shows the different states of a 203
process.
Every state diagram starts with an initial state,
which is the state where the object is created.
Terminated state
In process management, a state in which a 204
process has finished executing.
A process may be terminated, either from the
running state by completing its execution or by
explicitly being killed. In either of these cases,
the process moves to the terminated state.
Time sharing
Time-sharing is the sharing of a computing 195
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resource
among
many
users
by
means
of multiprogramming and multi-tasking.
Multiprogramming brought the idea of time
sharing: resources could be shared between
different jobs, with each job bring allocated a
portion of time to use a resource.
UNIX
A popular operating system among computer 209
programmers and computer scientists.
UNIX was originally developed in 1969 by
Thomson and Ritchie of the Computer Science
Research Group at Bell Laboratories.
User interface
A Program that accepts requests from users and 197
interprets them for the rest of the operating
system.
Each operating system has a user interface, a
program that accepts requests from users and
interprets them for the rest of the operating
system.
Utility
An application program in UNIX.
210
A utility is a standard UNIX program that
provides a support process for users.
Virtual memory
A form of memory organization that allows 202
swapping of programs between memory and
magnetic storage to give the impression of a
larger main memory than really exists.
The operating system manages virtual address
spaces and the assignment of real memory to
virtual memory.
Waiting state
A state in which a process is waiting to receive 203
the attention of the CPU.
Waiting states are a pure waste for a processor's
performance.
Windows
Microsoft Windows (or simply Windows) is a 211
metafamily
of graphical operating
systems developed, marketed, and sold by
Microsoft. It consists of several families of
operating systems, each of which cater to a
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certain sector of the computing industry.
Windows 1.0 was to compete with Apple's
operating system, but achieved little
popularity.
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