COSC 80 | Midterms Flashcards
(132 cards)
1
Q
a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware
A
Operating System
2
Q
a software that manages a computer’s hardware
A
Operating System
3
Q
Operating System is the one program running at all times on the computer (usually called ____), with all else being application programs
A
kernel
4
Q
the most important part of the operating system. It is the primary interface between the hardware and the processes of a computer
A
kernel
5
Q
Components of a computer system
A
- hardware
- application programs
- operating system
- users
6
Q
the central processing unit (CPU), the memory, and the I/O devices provides the basic computing resources for the system
A
hardware
7
Q
word processors, compilers, web browsers define the ways in which these resources are used to solve users’ computing problems;
A
application programs
8
Q
controls the hardware and coordinates its use among the various application programs for the various users
A
operating system
9
Q
users of a computer system
A
users
10
Q
Abstract view of the components of a computer system
A
user
application programs
operating system
computer hardware
11
Q
Typically, operating systems have a ____ for each device controller
A
device driver
12
Q
it understands the device controller and provides the rest of the operating system with a uniform interface to the device
A
device driver
13
Q
General-purpose computers run most of their programs from rewritable memory, called ____ (also called ____)
A
main memory
RAM or Random-Access Memory
14
Q
a flexible and volatile type of storage device
A
Main Memory
15
Q
commonly is implemented in a semiconductor technology called DRAM (Dynamic Random-Access Memory)
A
Main Memory
16
Q
a semiconductor technology called ____
A
DRAM (Dynamic Random-Access Memory)
17
Q
this instruction moves a byte or word from main memory to an internal register within the CPU
A
load instruction
18
Q
this instruction moves the content of a register to main memory
A
store instruction
19
Q
An Operating system is a ____. The system’s CPU, memory space, file-storage space, and I/O devices are among the resources that the operating system must manage
A
resource manager
20
Q
Resource Management in OS
A
- Process Management
- Memory Management
- File-System Management
- Mass-Storage Management
- Cache Management
- I/O System Management
21
Q
A ___ is a program in execution.
* A program such as compiler is a ___;
* A word-processing program being run by an individual user on a PC is a ___
A
process
22
Q
A process needs certain ___– it includes CPU time, memory, files, and I/O devices–to accomplish its task.
* These ___ are typically allocated to the process while it is running.
* In addition to the physical and logical resources that a process obtains when it is created, various initialization data (input) may be passed along.
A
resources
23
Q
A program is a ___, like the contents of a file stored on disk, whereas a process is an ___.
* The execution of such a process must be sequential.
* The CPU executes one instruction of the process after another, until the process completes
A
passive entity
active entity
24
Q
A ___ is the unit of work in a system. A system consists of collection of processes, some of which are operating-system processes and the rest of which are user processes.
A
process
25
___ is central to the operation of a modern computer system.
* ___ is a repository of quickly accessible data shared by the CPU and I/O devices.
* The ____ is generally the only large storage device that the CPU is able to address and access directly
Main Memory
26
To improve both the utilization of the CPU and the speed of the computer’s response to its users, general-purpose computers must keep several programs in memory, creating a need for ____
memory management
27
____ is one of the most visible components of an operating system
File Management
28
in file management, physical media such as __ is the most common, but ___ is also possible
secondary storage
tertiary storage
29
A ___ is a collection of related information defined by its creator.
* Commonly, ___ represent programs (both source and object forms) and data.
file
30
___ may be numeric, alphabetic, alphanumeric or binary
Data files
31
Files may be __ like text files or formatted rigidly such as mp4 file format
free-form
32
Most modern computer systems use ___ as the principal on-line storage media for both programs and data.
* Most programs – including compilers, web browsers, word processors, and games – are stored on these devices until loaded into memory.
HDDs and NVM devices
33
Since secondary storage is used frequently and extensively, it must be used ___.
* The entire speed of operation of a computer may hinge on the speeds of the secondary storage sub-system and the algorithms that manipulate that sub-system
efficiently
34
___ is an important principle of computer systems. In ___, information is normally kept in some storage system (such as main memory).
* As it is used, it is copied into a faster storage system – the __ - on a temporary basis.
Caching
Cache
35
Because caches have limited size, ___ is an important design problem.
* Careful selection of the cache size and of a replacement policy can result in greatly increased performance
cache management
36
One of the purposes of an operating system is to hide the peculiarities of specific hardware devices from the user.
For example, in UNIX, the peculiarities of I/O devices are hidden from the bulk of the operating system itself by the ___.
I/O subsystem
37
this type of operating system does not interact with the computer directly
Batch Operating System
38
An __ is present which takes similar jobs having the same requirement and groups them into batches
operator
39
___ can be illustrated as more than one program is present in the main memory and any of them can be kept in execution.
* As a result, various jobs may share CPU time.
Multiprogramming Operating Systems
40
___ is a type of operating system in which more than one CPU is used for the execution of resources
Multiprocessing Operating System
41
___ is simply a multiprogramming operating system with having facility of a Round-Robin Scheduling Algorithm.
* It can run multiple programs simultaneously
Multitasking Operating System
42
___ – each task is given some time to execute so that all the tasks work smoothly.
* Each user gets the time of the CPU as they use a single system.
* The task can be from a single user or different users
Time-Sharing Operating Systems
43
___ – it uses many central processors to serve multiple real-time applications and users.
* Independent systems process their own memory unit and CPU
Distributed Operating System
44
___ – These systems run on a server and provide the capability to manage data, users, groups, security, applications, and other networking functions.
* These types of operating systems allow shared access to files, printers, security, applications, and other networking functions over a small private network.
Network Operating System
45
it provides an environment for the execution of programs
operating system
46
One set of operating system services provides functions that are helpful to the user:
- user interface
- program execution
- i/o operations
- file-system manipulation
- communications
- error detection
47
Another set of operating-system functions is for ensuring the efficient operation of the system itself:
- resource allocation
- logging
- protection and security
48
The interface is a window system with a mouse that servers as a pointing device to direct I/O, choose from menus, and make selections and a keyboard to enter text
graphical user interface
49
it uses text commands and a method for entering them is also another option
command-line interface
50
The system must be able to load a program into memory and to run that program. The program must be able to end its execution, either normally or abnormally.
program execution
51
A running program may require I/O, which may involve a file or an I/O device. For specific devices, special functions may be desired (such as reading from a network interface or writing to a file system). For efficiency and protection, users usually cannot control I/O devices directly. Therefore, the operating system must provide a means to do I/O
I/O operations
52
Programs need to read and write files and directories. They also need to create and delete them by name, search for a given file, and list file information. Finally, some operating systems include permissions management to allow or deny access to files or directories based on file ownership
file-system manipulation
53
it may be implemented via shared memory or message passing
communications
54
two or more processes read and write to a shared section of memory
shared memory
55
packets of information in predefined formats are moved between processes by the operating system
message passing
56
The operating system needs to be detecting and correcting errors constantly. Errors may occur in the CPU and memory hardware, in I/O devices, and in the user program. For each type of error, the operating system should take the appropriate action to ensure correct and consistent computing
error detection
57
When there are multiple processes running at the same time, resources must be allocated to each of them. The operating system manages many different types of resources. Some may have special allocation code, whereas others may have much more general request and release code
resource allocation
58
This record keeping may be used for accounting (so that users can be billed) or simply accumulating usage statistics. Usage statistics may be valuable tool for system administrators who wish to reconfigure the system to improve computing services
logging
59
it involves ensuring that all access to system resources is controlled
protection
60
starts with requiring each user to authenticate himself or herself to the system, usually by means of a password, to gain access to system resources
security
61
a special program that is running when a process is initiated or when a user first logs on
command interpreter
62
the interpreters are known as ___
shells
63
The main function of the ___ is to get and execute the next user-specified command
command interpreter
64
Rather than entering commands directly via a command-line interface, users employ a mouse-based window-and-menu system characterized by a desktop metaphor. The user moves the mouse to position its pointer on images, or icons, on the screen (the desktop) that represent programs, files, directories, and system functions
graphical user interface
65
users interact by making gestures on the touch screen – for example, pressing and swiping fingers across the screen. Although earlier smartphones included a physical keyboard, most smartphones and tablets now simulate a keyboard on the touch screen
touch-screen interface
66
it provides an interface to the services made available by an operating system. These calls are generally available as functions written in C and C++
system calls
67
it specifies a set of functions that are available to an application programmer, including the parameters that are passed to each function, and the return values the programmer can expect
application programming interface
68
Actual system calls can often be more detailed and more difficult to work with than the API available to an application programmer
true or false
true
69
the full suite of software needed to execute applications written in a given programming language, including its compilers or interpreters as well as other software, such as libraries and loaders
run-time environment
70
RTE provides ___ that serves as the link to system calls made available by the operating system
System-Call Interface
71
it intercepts function calls in the API and invokes the necessary system calls within the operating system
System-Call Interface
72
a number is associated with each system call, and the system-call interface maintains a table indexed according to these numbers
true or false
true
73
The simplest approach to pass parameters to the operating system is to pass the parameters in indexes
true or false
false
The simplest approach to pass parameters to the operating system is to pass the parameters in registers
74
types of system calls
- process control
- file management
- device management
- information maintenance
- communication
- protection
75
A running program needs to be able to halt its execution normally. If a system call is made to terminate the currently running program abnormally, or if the program runs into a problem and causes an error trap, a dump of memory is sometimes taken and an error message generated
process control
76
In this, either system call requires the name of the file and perhaps some of the file’s attributes
file management
77
A process may need several resources to execute–main memory, disk drives, access to files, and so on.
If the resources are available, they can be granted, and control can be returned to the user process. Otherwise, the process will have to wait until sufficient resources are available
device management
78
Many system calls exist simply for the purpose of transferring information between the user program and the operating system
information maintenance
79
the communicating process exchange messages with one another to transfer information. Messages can be exchanged between the processes either directly or indirectly through a common mailbox
message-passing model
80
processes such as shared_memory_create() and shared_memory_attach() system calls to create and gain access to regions of memory owned by other processes
shared-memory model
81
it provides a mechanism for controlling access to the resources provided by a computer system
protection
82
security was a concern only on multi-programmed computer systems with several users
true or false
false
protection was a concern only on multi-programmed computer systems with several users
83
it also known as system utilities– it provides a convenient environment for program development and execution. Some of them are simply user interfaces to system calls
system services
84
what are the system services?
- file management
- status information
- file modification
- programming-language support
- program loading and execution
- communications
- background services
85
these programs create, delete, copy, rename, print, list, and generally access and manipulate files and directories
file management
86
some programs simply ask the system for the date, time, amount of available memory or disk space, number of users, or similar status information
status information
87
Some systems also support a ____, which is used to store and retrieve configuration information
registry
88
Several text editors may be available to create and modify the content of files stored on disk or other storage devices
file modification
89
compilers, assemblers, debuggers, and interpreters for common programming languages (such as C, C++, Java, and Python) are often provided with the operating system or available as separate download
programming-language support
90
once a program is assembled or compiled, it must be loaded into memory to be executed. The system may provide absolute loaders, relocatable loaders, linkage editors, and overlay loaders
program loading and execution
91
These programs provide the mechanism for creating virtual connections among processes, users, and computer systems. They allow users to send messages to one another’s screens, to browse web pages, to send e-mail messages, to log in remotely, or transfer files from one machine to another
communications
92
all general-purpose systems have methods for launching certain system-program processes at boot time. Some of these processes terminate after completing their tasks, while others continue to run until the system is halted
background services
93
A ___is a program in execution
Process
94
A Program is passive; a process is active
true or false
true
95
The OS has to load executable from hard disk to main memory, keep track of the ___ of each process currently executed
states
96
A Process consists of (at least)
address space
cpu state
os resources
97
The code (instructions) for the running program;
The data for the running program (static data, heap data, stack)
address space
98
The program counter (PC), indicating the next instruction;
Stack pointer
Other general purpose register values
CPU state
99
open files, network connections, sound channels, etc.
OS resources
100
process state
- new
- running
- waiting (blocked)
- ready
- terminated
101
The process is about to be created but not yet created. It is the program that is present in secondary memory that will be picked up by OS to create the process
new
102
The process is chosen from the ready queue by the CPU for execution and the instructions within the process are executed by any one of the available CPU cores.
running
103
Whenever the process is waiting for an event, it enters the waiting state or block state. The process continues to wait in the main memory and does not require CPU.
waiting (blocked)
104
After the creation of a process, the process enters the ready state
ready
105
Processes that are ready for execution by the CPU are maintained in a queue called
The process is ready to run and I waiting to get the CPU
time for its execution.
ready queue
106
The process is released or de-allocated
terminated
107
Each process is represented in the operating system by a ___ also called a task control block. ___ contains information associated with a specific process
process control block (PCB)
108
process control block includes
- process state
- program counter
- CPU registers
- CPU-scheduling information
- memory-management information
- accounting information
- I/O status information
109
The state may be new, ready, running, waited, halted, etc.
process state
110
The counter indicates the address of the next instruction to be executed for this process.
program counter
111
This information includes a process priority, pointers to scheduling queues, and any other scheduling parameters.
CPU-scheduling information
111
The registers vary in number and type, depending on the computer architecture. They include accumulators, index registers, stack pointers, and general-purpose registers. Along with the program counter, this state information must be saved when an interrupt occurs, to allow the process to be continued correctly afterward when it is re-scheduled to run.
CPU registers
112
This information may include such items as the value of the base and limit registers and the page tables, or the segment tables, depending on the memory system used by the operating system
memory-management information
113
This information includes the list of I/O devices allocated to the process, a list of open files, etc.
I/O status information
113
This information includes the amount of CPU and real time used, time limits, account numbers, job or process numbers, etc.
accounting information
114
it selects an available process (possibly from a set of several available processes) for program execution on a core. Each CPU core can run one process at a time.
process scheduler
115
contains those processes that are ready to run
ready queue
116
contains those processes that are waiting for a certain event to occur
wait queue
117
it is a task where switching the CPU core to another process requires performing a state save of the current process and a state restores of a different process.
context switch
118
performs a state save of the current state of the CPU core
state save
119
to resume operations
state restore
120
Categories in Scheduling falls into two categories
non-preemptive and preemptive
121
a process’s resource cannot be taken before the process has finished running. When a running process finishes and transitions to a waiting state, resources are switched
non-preemptive
122
the OS assigns resources to a process for a predetermined period of time. The process switches from running state to ready state or from waiting state to ready state during resource allocation. This switching happens because the CPU may give other processes priority and substitute the currently active process for the higher priority process
preemptive
123
process schedulers
- long term or job scheduler
- short-term or CPU scheduler
- medium-term scheduler
124
* ____ brings the new process to the Ready State. It controls the Degree of Multi-programming, i.e., the number of processes present in a ready state at any point in time.
* It increases efficiency by maintaining a balance between I/O and CPU-bound processes.
* They operate at a high level and are typically used in batch-processing systems.
Long term scheduler
125
* ___ is responsible for selecting one process from the ready state for scheduling it on the running state.
* In ____, all scheduling algorithms are used.
* The ____ is responsible for ensuring no starvation due to high burst time processes.
Short-Term scheduler or CPU scheduler
126
it is responsible for loading the process selected by the Short-term scheduler on the CPU (Ready to Running State) Context switching is done by ____ only
the dispatcher
127
The dispatcher does the following:
* Switching Context;
* Switching to user mode;
* Jumping to the proper location in the newly loaded program.
128
It is responsible for suspending and resuming process. It mainly does swapping (moving processes from main memory to disk and vice versa).
It is helpful in maintaining a perfect balance between the I/O bound and the CPU bound.
It reduces the degree of multiprogramming.
medium-term scheduler
129
it may be necessary to improve the process mix or because a change in memory requirements has overcommitted available memory, requiring memory to be freed up.
swapping
130
the number of processes present in a
ready state at any point in time
degree of multi-programming
