WGU - C191 - Operating Systems for Programmers
Which of the following is a property of peer-to-peer systems? A. Clients and servers are not distinguished from one another. B. Peer-to-peer systems do not offer any advantages over traditional client-server systems. C. Peer-to-peer systems suffer from the server acting as the bottleneck in performance.
A. Clients and servers are not distinguished from one another. In a peer-to-peer system, no difference exists between a client and a server. All nodes are considered peers and may act as either a client or a server. Why is B wrong? Peer-to-peer offers advantages over traditional client-server computing as nodes providing a service can be distributed throughout a network, providing a layer of redundancy. In traditional client-server computing, a single server may become overwhelmed by requests and create a performance bottleneck. Why is C wrong? An overloaded server may become a performance bottleneck in traditional client-server computing, but peer-to-peer systems allow any node throughout the system to act as a server and avoid possible bottlenecks.
The following are definitions of operating environments. Select the best definition for real-time system. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
A. Computer that must respond rapidly to external events
3 independent processes are executing on 2 physical CPUs. Decreasing the number of CPUs from 2 to 1 will __________ speed of execution. A. Decrease B. Increase C. Not affect
A. Decrease All 3 processes will have to time-share the single CPU. 1 CPU provides less computational power than 2, so the speed of execution will not increase or stay the same.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Load a program into memory. A. Definitely B. Not necessarily
A. Definitely The OS must manage the partitioning of memory to protect concurrent users from one another and to optimize the use of memory.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Sleep for n seconds. A. Definitely B. Not necessarily
A. Definitely The OS must select and run another program while the requesting program is blocked to avoid wasting CPU time and other resources.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Exit current program. A. Definitely B. Not necessarily
A. Definitely When a program terminates, the OS must free up memory and other resources used by the program.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Input a character from the keyboard. A. Definitely B. Not necessarily
A. Definitely. All devices require OS support to carry out the complex interactions transparently to the user.
Changing the mode bit of the CPU _____ can only be done by a privileged instruction. A. From user mode to kernel mode B. From kernel mode to user mode C. In any way
A. From user mode to kernel mode Changing from user mode to kernel mode must be done in a controlled manner using a supervisor call instruction.
Will the PCB field of CPU_state change during a process's lifetime? A. May change B. Will not change
A. May change The CPU_state changes during every context switch.
Will the PCB field of memory change during a process's lifetime? A. May change B. Will not change
A. May change The amount of memory needed by a process typically varies over time and is adjusted accordingly.
Will the PCB field of open_files change during a process's lifetime? A. May change B. Will not change
A. May change The process can open and close any number of files during execution.
Will the PCB field of process_state change during a process's lifetime? A. May change B. Will not change
A. May change The process_state keeps changing as the process requests resources or is moved to/from the CPU.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Call a shared library function. A. Most likely B. Not necessarily
A. Most likely Due to the large numbers of possible library functions, the OS may postpone the loading and linking of a function until the function is actually needed.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Allocate n bytes of memory for a new data structure. A. Most likely B. Not necessarily
A. Most likely The OS must manage the partitioning of memory to protect concurrent users from one another and to optimize the use of memory. Some portion of the dynamic memory could be pre-allocated but, in general, an OS intervention is required.
Privileged instructions may be executed by _____. A. Only the kernel B. The kernel and system call libraries C. Any program
A. Only the kernel No program outside of the kernel is allowed to use privileged instructions.
Which of the following distinguishing OS features corresponds to the 5th generation? A. Parallel and distributed computing B. No OS support C. Time-sharing, keyboard and display terminal support D. User-friendly GUI E. Batch processing, multiprogramming
A. Parallel and distributed computing Connecting multiple CPUs and memories into a supercomputer enabled high-performance computing. Connecting multiple computers into networks enabled internet commerce, information sharing, and social interactions.
A supervisor call is a _____. A. Privileged instruction B. Library function C. Kernel function
A. Privileged instruction A supervisor call is a privileged instruction that transfers control to the kernel in kernel mode.
A/an ___ is an instance of a program in execution. A. Process B. Operating system C. Program counter
A. Process A process is an active entity and represents a program running on the computer system. Why is B wrong? An operating system is the collection of data objects and procedures that are invoked by CPU on interrupts and exceptions (such as traps, division by 0, etc.). Why is C wrong? A program in execution requires maintaining the next instruction to be performed and the the program counter holds the address of this next instruction.
Embedded computers typically run on a ____ operating system. A. Real-time B. Mobile C. Client-server
A. Real-time Embedded systems typically have strict timing requirements that are supported by real-time operating systems where a task must be guaranteed to complete within a specific amount of time or the system will fail. To provide support for tasks that have specific timing requirements, real-time operating systems are usually designed much differently than general-purpose operating systems.
A ______ is another term for command interpreter. A. Shell B. Shell script C. Gesture
A. Shell There are many different shell programs that can be used as a command interpreter, including C-shell, Korn-shell and the bash shell. Why is B wrong? A shell script is a program containing a series of commands that are run by a command interpreter. Why is C wrong? Gestures refer to the motions made by users as they press and move their hands across a touch screen interface, one alternate interface to the command interpreter for interacting with a computer system.
Which of the following statements concerning open source operating systems is true? A. Source code is made available. B. Open source operating systems are always more secure than commercial, closed systems. C. All open source operating systems share the same set of goals.
A. Source code is made available. Making source code for the operating systems available is a hallmark feature of both free operating systems and open-source operating systems. Why is B wrong? No guarantees exist that open source operating systems are more secure than commercial, closed-source systems. Both open and closed operating systems have had security breaches. Why is C wrong? Although open source operating systems share the common goal of making the source code available, open source operating systems all have different goals, including making the software available at no cost or charging a fee.
The transition (ready -> running) of a process p is caused by _____. A. The OS B. The process p itself C. Some other process
A. The OS Only the OS has the authority to decide when a process should continue to run and can perform the transition.
The transition (running -> ready) of a process p is caused by _____. A. The OS B. The process p itself C. Some other process
A. The OS The OS may wish to let some other process use the CPU. p has no reason to voluntarily give up the CPU. Only the OS has the authority to stop a running process.
Which of the following operating systems is not open source? A. Windows B. Solaris C. GNU/Linux
A. Windows Windows is a closed, commercial operating system with no source code availability. Although Solaris at one point was a closed, commercial operating system, Solaris was made available as an open source operating system in 2005. GNU/Linux is perhaps the best example of an open source operating system where the source code for all of Linux is made freely available.
The invention of integrated circuits marks the transition to the _____ generation of computer systems. A. 2nd B. 3rd C. 4th
B. 3rd Integrated circuits enabled the placement of many transistors on a single chip, thus marking the transition from the 2nd to the 3rd generation. The 2nd generation is associated with transistors. The 4th generation is associated with microprocessors.
The kernel can execute _____ instructions. A. Only privileged B. Both privileged and non-privileged
B. Both privileged and non-privileged The kernel always executes in kernel mode, which allows the use of privileged instructions in addition to non-privileged instructions.
A supervisor call can be executed _____. A. Only in kernel mode B. By any program C. By only library functions
B. By any program A supervisor call is an instruction that switches from user mode to kernel mode. Any program can make direct use of a kernel function by issuing the corresponding supervisor call.
Which of the following typical OS types is associated with very large scale integration? A. Batch OS B. Desktop and laptop OS C. Interactive multi-user OS D. OS for supercomputers, distributed systems, and mobile devices E. None
B. Desktop and laptop OS Very large scale integration (VLSI) allowed the development of on-chip microprocessors, leading to the development of personal desktop and laptop computers.
A ___ is a custom build of the Linux operating system. A. LiveCD B. Distribution C. VMWare Player
B. Distribution Several distributions of the Linux operating system exist. Distributions are custom-built so the build of the operating system may vary. Why is A wrong? A LiveCD is an operating system that can be booted and run from a CD-ROM rather than installing the operating system on the user's hard drive. A custom build of the Linux operating system could be made available via a LiveCD, but other operating systems, in addition to Linux, can be made available as well. Why is C wrong? VMWare player is software that runs on Windows, not Linux, and allows users to run other operating systems as applications known as virtual appliances.
A _____ provides a file-system interface which allows clients to create and modify files. A. Compute-server system B. File-server system C. Software as a service
B. File-server system A file-server system not only allows allows clients to create and modify files, but files can also be stored on the file server. Why is A wrong? A compute-server system is a client-server system where clients make requests to a server and the server "computes" the result and returns the result back to the client. Compute-server systems are not involved with the management and maintenance of files. Why is C wrong? Software as a service makes applications such as word processors and spreadsheets available via the internet and does not specifically only provide a file-system interface for creating and modifying files.
In a hypothetical system, the average computation spends 50% of total time using the CPU and the remaining 50% waiting for I/O. The use of time-sharing will _____. A. Speed up all computations B. Guarantee reasonable response to each computation C. Improve resource utilization
B. Guarantee reasonable response to each computation No computation can monopolize the CPU indefinitely.
Which of the following forms of storage has the largest capacity? A. Registers B. Hard-disk drives C. Nonvolatile memory
B. Hard-disk drives Although hard-disk drives don't have as much capacity as tertiary storage (optical disks and magnetic tapes), hard-disk drives have more storage capacity than both registers and nonvolatile memory.
3 independent processes are executing on 2 physical CPUs. Increasing the number of CPUs from 2 to 3 will __________ speed of execution. A. Decrease B. Increase C. Not affect
B. Increase Each of the 3 processes can now have a separate physical CPU.
An application that needs to access an I/O device could not be written without _____. A. Kernel and library functions B. Kernel functions
B. Kernel functions To access an I/O device, privileged instructions are needed, which only the kernel can execute. The application could rely on only kernel functions to access and use the I/O device. Library functions just provide more convenient access.
The following are definitions of operating environments. Select the best definition for mainframe. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
B. Large central computer used by large organizations
A system call is a _____. A. Privileged instruction B. Library function C. Kernel function
B. Library function A system call is a library function that uses supervisor calls to carry out a service function. It invokes kernel functions, but is itself more of a high-level operation than a kernel function.
In a hypothetical system, the average computation spends 50% of total time using the CPU and the remaining 50% waiting for I/O. To achieve best CPU utilization, _____ computations should run simultaneously. A. 2 B. More than 2 C. All available
B. More than 2 Using more than 2 computations increases CPU utilization but at the same time uses more memory and other resources. A careful balance must be found to minimize overhead while still increasing overall performance.
Which of the following distinguishing OS features corresponds to the 1st generation? A. Parallel and distributed computing B. No OS support C. Time-sharing, keyboard and display terminal support D. User-friendly GUI E. Batch processing, multiprogramming
B. No OS support Computers used vacuum tubes and magnetic drums for storage to perform computations without any software support.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Change the layout of a document. A. Definitely B. Not necessarily
B. Not necessarily A document is manipulated by a text editor. If the document is in memory then the change is made without requiring any OS services.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Call a function defined within the current program. A. Definitely B. Not necessarily
B. Not necessarily The compiler and the linker combine functions into a single module, where the call results in a branch instruction within the program. No OS involvement is needed.
The hardware/user gap is bridged by the OS or by other system software. Would the following task require OS support? Invoke a high-level matrix manipulation operation. A. Definitely B. Not necessarily
B. Not necessarily The compiler can translate high-level operations on complex data structures into the corresponding machine instructions, which then execute without any help of the OS.
An advanced aircraft is likely to have a _____ on board to help control the aircraft. A. Mainframe computer B. Real-time computer C. Desktop PC
B. Real-time computer Many functions of a modern aircraft depend on electronic circuits and computer systems, which need to respond in real-time to commands and sensor inputs. Mainframes are too large for most aircraft to carry on board. A desktop PC may fit on board, but would not be used to control the aircraft.
Which of the following operating system services is related to ensuring the efficient operation of the system and is unrelated to providing services to user programs? A. Program execution B. Resource allocation C. Communication
B. Resource allocation The operating system must allocate resources such as the CPU, main memory, and file storage for user programs while managing these limited resources to provide efficient overall operation of the computing system. Why is A wrong? The operating system provides features that allow a user to load a program into memory and run the program. Why is C wrong? Operating systems provide communication features that allow user programs to exchange data and information with one another.
Two important design issues for cache memory are ___. A. Speed and volatility B. Size and replacement C. Policy size and access privileges
B. Size and replacement The size of cache memory is small and because of this limitation, the replacement policy for managing data is crucial to gaining the most benefit from cache memory. Why is A wrong? Although cache memory is volatile (requires the computer to be powered-on to store data) , speed is not an issue as cache memory is the fastest form of memory after hardware registers. Why is C wrong? The size of cache memory is small, however there are generally no issues with access privileges for cache memory.
When the CPU with floating operations is replaced with a CPU without floating point operations, then __________. A. The correctness of the operations may change B. Speed of execution may change
B. Speed of execution may change The virtual CPU software will implement the same operations as the hardware but the hardware implementation is likely to be faster.
The transition (running -> blocked) of a process p is caused by _____. A. The OS B. The process p itself C. Some other process
B. The process p itself p causes the transfer when requesting a currently unavailable resource. The OS only executes the transfer. p becomes blocked only as a result of a failed resource request and thus only p can cause the transition.
The PCB contains an up-to-date copy of the CPU state of a process p _____ . A. When p's state is running B. When p's state is ready or blocked C. At all times
B. When p's state is ready or blocked At this point, p's PCB contains an exact copy of the CPU state at the point when p transitioned out of the running state. This CPU state is restored when p transitions back to the running state. Why is A wrong? The CPU state is stored in the PCB when the CPU is switched from p to some other process. While p's state is running, the CPU state keeps changing and the changes are not written back to the PCB until p transitions out of the running state. Why is C wrong? Only when p's state is not running does the PCB contain an up-to-date copy of the CPU state. When p's state is running, the CPU is advancing p's program counter with each instruction, but the PCB copy is not updated until p is transitioned out of the running state.
The invention of microprocessors marks the transition to the _____ generation of computer systems. A. 2nd B. 3rd C. 4th
C. 4th Using VLSI, an entire processor could be placed on a single chip, thus marking the transition from the 3rd to the 4th generation. The 2nd generation is associated with transistors. The 3rd generation is associated with integrated circuits.
A device controller informs a device driver it has completed an I/O operation using ________. A. Direct memory access (DMA) B. An interrupt handler C. An interrupt
C. An interrupt An interrupt is the mechanism a computer system uses for a device controller to inform the CPU about the change of status related to an I/O. Why is A wrong? Direct memory access (DMA) allows device controllers to move data between a devices and main memory without any intervention from the CPU. DMA only moves the data and requires another mechanism for informing the operating system the I/O operation is complete. Why is B wrong? The CPU will call an interrupt handler on an interrupt caused by the device controller after an I/O operation has completed.
Kernel functions may be invoked by _____. A. Only system call libraries B. Only system call or general libraries C. Any program
C. Any program Any program is allowed to issue a supervisor call to request service directly from the kernel.
Mainframes are considered _____. A. Supercomputers B. Embedded computers C. General-purpose computers
C. General-purpose computers Mainframes are stand-alone systems that can be programmed to perform a wide variety of tasks. Embedded computers are integral parts of any electro-mechanical system. Supercomputers generally encompass large numbers of CPUs and memories that work together in solving large computational problems.
Which of the following typical OS types is associated with integrated circuits? A. Batch OS B. Desktop and laptop OS C. Interactive multi-user OS D. OS for supercomputers, distributed systems, and mobile devices E. None
C. Interactive multi-user OS Integrated circuits allowed the development of microchips, which greatly reduced the size of computers and allowed the introduction of interactive computing.
The following are definitions of operating environments. Select the best definition for server. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
C. Large computer that responds to requests from individual clients
3 independent processes are executing on 2 physical CPUs. Increasing the number of CPUs further from 3 to 4 will __________ speed of execution. A. Decrease B. Increase C. Not affect
C. Not affect Each process can only use one CPU and thus only 3 CPUs can be utilized.
____ is not one of the major categories of system calls. A. Process control B. Communications C. Security
C. Security Security of a computer system is generally based on applying general security policies and not any specific system calls. Why is A wrong? There are system calls for creating, managing, and terminating processes. Why is B wrong? There are system calls that allow two, or more, processes to communicate. Communication may occur using either shared memory or message passing.
Examples of the _______ model include applications such as word processors or spreadsheets that run in the cloud and may be accessed via the internet. A. Platform as a service B. Hybrid cloud C. Software as a service
C. Software as a service Software as a service views applications such as word processors, spreadsheets, and presentation software as specific services that can be made available over the internet. Why is A wrong? Although platform as a service is made available via the internet, platform as a service is more than specific applications and provides an entire stack of software services such as database servers. Why is B wrong? A cloud can be used to deliver word processors and spreadsheets via the internet, but a hybrid cloud indicates the cloud infrastructure consists of both a public and private component.
The transition (blocked -> ready) of a process p is caused by _____. A. The OS B. The process p itself C. Some other process
C. Some other process p is waiting for a resource held by or generated by some other process q. The release of the resource or data by q causes the transition of p back to ready. The OS cannot make p ready until the requested resource or input data becomes available. p is not running and so cannot perform any actions.
What multiprocessors and multi- computers (distributed systems) have in common is _____. A. The same type of applications B. The same type of interconnection networks C. The ability to carry out operations in parallel
C. The ability to carry out operations in parallel Both types of computer contain multiple CPUs, interconnected and cooperating in different ways, which allow multiple computations to proceed in parallel. Why is A wrong? Multiprocessors perform high-speed parallel computations. Multi-computers are networks of independent nodes, used primarily for the exchange of information and services. Application types may differ significantly between the two. Why is B wrong? Multiprocessors require specialized and very fast interconnections among CPUs and memories. Multi-computers use a variety of networks, ranging from local area networks to public phone lines, and satellite/wireless connections.
Which of the following distinguishing OS features corresponds to the 3rd generation? A. Parallel and distributed computing B. No OS support C. Time-sharing, keyboard and display terminal support D. User-friendly GUI E. Batch processing, multiprogramming
C. Time-sharing, keyboard and display terminal support Interrupts enabled time-sharing of the CPU among multiple users, who interacted with the system using keyboards and cathode-ray display terminals.
When a process p is moved from the current state (running, ready, or blocked) to the suspended state, then upon reactivation, ________. A. p must be moved back to the same state where the suspension occurred B. p can always safely be moved to the ready state C. p is moved to either the ready or the blocked state
C. p is moved to either the ready or the blocked state If the suspension occurred in the blocked state then p must go back to the blocked state. If the suspension occurred in the running or ready state then p must go to the ready state.
The following are definitions of operating environments. Select the best definition for multi-computer. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
D. Network of independent computers
Which of the following typical OS types is associated with networking hardware? A. Batch OS B. Desktop and laptop OS C. Interactive multi-user OS D. OS for supercomputers, distributed systems, and mobile devices E. None
D. OS for supercomputers, distributed systems, and mobile devices Networking hardware enabled the harnessing of the power of multiple computers, leading to supercomputers, distributed systems, and mobile devices.
Which of the following distinguishing OS features corresponds to the 4th generation? A. Parallel and distributed computing B. No OS support C. Time-sharing, keyboard and display terminal support D. User-friendly GUI E. Batch processing, multiprogramming
D. User-friendly GUI Microprocessors gave rise to the personal computer, which required an intuitive, easy-to-use interface even for the casual user.
Which of the following distinguishing OS features corresponds to the 2nd generation? A. Parallel and distributed computing B. No OS support C. Time-sharing, keyboard and display terminal support D. User-friendly GUI E. Batch processing, multiprogramming
E. Batch processing, multiprogramming Multiprogramming improved the throughput of jobs submitted in batches of punch cards.
The following are definitions of operating environments. Select the best definition for desktop/laptop. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
E. Personal computer
The following are definitions of operating environments. Select the best definition for hand-held device. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
F. Small, portable, wireless-capable device for personal use
True or False: An application running on multiple physical CPUs must be modified in order to run correctly on a single CPU.
False A process can run on a dedicated CPU or with interruptions on a shared CPU. The context switches are transparent to the process, and the results are unaffected.
True or False: When a ready process p wishes to temporarily stop competing for the CPU, p moves itself to the suspended state.
False A process in the ready state is not running program code and so cannot perform any actions. Only the OS or p's creator (parent) can move p to the suspended state.
True or False: Virtual machine managers allow to make snapshots of host system.
False Many operating systems provide that basic feature for processes, but VMMs go one step further and allow copies and snapshots to be made of the guest.
True or False: Host system is protected from a virtual machine, but several virtual machines running on the same host are not protected from each other.
False One important advantage of virtualization is that the host system is protected from the virtual machines, just as the virtual machines are protected from each other. A virus inside a guest operating system might damage that operating system but is unlikely to affect the host or the other guests. Because each virtual machine is almost completely isolated from all other virtual machines, there are almost no protection problems.
True or False: The main objective of time-sharing is to improve resource utilization.
False Resource utilization is improved by multiprogramming, which overlaps CPU-bound and I/O-bound computations. Time-sharing only switches the CPU among different computations to create the illusion of simultaneous execution, which generally does not improve resource utilization beyond simple multiprogramming.
True or False: A context switch for a currently running process p may be caused by some other process q.
False The OS can take the CPU away from a running process p, or p can give up the CPU by requesting an unavailable resource. But some other process q cannot cause a context switch for process p.
True or False: The PCB is created by the process when execution starts.
False The PCB is a data structure created and maintained only by the OS, not by the process itself.
True or False: When a newly created process p is ready to compete for the CPU, p moves itself from the new to the ready state.
False The purpose of the new state is to allow the OS to control how many processes are competing for the CPU and thus only the OS can cause a transition from new to ready.
True or False: Multiprogramming and time-sharing are not used together.
False Time-sharing requires multiprogramming, since multiple computations must be active at the same time.
True or False: The main purpose of virtual CPUs is to improve the performance of a system.
False Virtual CPUs allow processes to transparently share a physical CPU, generally at the cost of reduced speed. Virtual CPUs also allow processes to run different physical CPUs without code modification or recompilation.
True or False: When a blocked process p is suspended and the resource needed by p becomes available, p is moved to the ready state.
False p is suspended for a reason different from waiting for a resource. Thus p must remain in the suspended state until explicitly reactivated. Only then is the process moved to the ready state.
True or False: The PCB becomes part of the program being executed by a process.
False The PCB is an independent data structure managed by the OS that is destroyed when the process terminates. The program remains unchanged.
The following are definitions of operating environments. Select the best definition for multiprocessor. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
G. System of multiple CPUs and memories interconnected by a fast network
Which of the following are typical defining characteristics of desktop and laptop OS? (Select Multiple) Time-Sharing Multiprogramming Parallel/distributed computing Networking GUI Interrupts Programs submitted on punch cards
GUI GUI is associated with desktop and laptop OS. GUI provides an intuitive interface for casual users.
The following are definitions of operating environments. Select the best definition for sensor network. A. Computer that must respond rapidly to external events B. Large central computer used by large organizations C. Large computer that responds to requests from individual clients D. Network of independent computers E. Personal computer F. Small, portable, wireless-capable device for personal use G. System of multiple CPUs and memories interconnected by a fast network H. Wired or wireless network of small, spatially distributed dedicated devices
H. Wired or wireless network of small, spatially distributed dedicated devices
Which of the following are typical defining characteristics of batch OS? (Select Multiple) Time-Sharing Multiprogramming Parallel/distributed computing Networking GUI Interrupts Programs submitted on punch cards
Multiprogramming, programs submitted on punch cards Multiprogramming and programs submitted on punch cards are associated with batch OSs. Multiprogramming allows the OS to make more efficient use of the CPU and other resources. Each program was represented by a sequence of punch cards, which were submitted in batches for processing.
Which of the following are typical defining characteristics of OS for supercomputers, distributed systems, and mobile devices? (Select Multiple) Time-Sharing Multiprogramming Parallel/distributed computing Networking GUI Interrupts Programs submitted on punch cards
Networking, parallel/distributed computing Networking and parallel/distributed computing are associated with OSs for supercomputers, distributed systems, and mobile devices. Networking allows multiple computers to exchange information. Parallel/distributed computing is enabled by interconnecting multiple computers or CPUs.
__________ provide an interface to the services made available by an operating system.
System calls Operating systems make their services available to application programmers by system calls.
Which of the following are typical defining characteristics of interactive multi-user OS? (Select Multiple) Time-Sharing Multiprogramming Parallel/distributed computing Networking GUI Interrupts Programs submitted on punch cards
Time-sharing, interrupts Time-sharing and interrupts are associated with interactive multi-user OSs. Time-sharing allows multiple users to utilize the systems at the same time. Interrupts allow the OS to enforce time-sharing and to support keyboards and display terminals.
True or False: Two processes can be executing the same program.
True A program can be executed multiple times simultaneously, each instance being a process. Each PCB has a separate program counter to keep track of each process' execution location in the program.
True or False: The transition of a process p from running to terminated can be caused by p itself.
True Completing all work or causing a fatal error causes p to transition from running to terminated.
True or False: Multiprogramming generally improves CPU utilization and throughput.
True Multiprogramming overlaps phases of computation and I/O from different computations to better utilize the CPU and other resources, which improves overall performance.
True or False: An OS uses a PCB to represent a process.
True The OS implements every process as a data structure called PCB, the process control block.
True or False: A context switch for a currently running process p may be caused by the OS.
True The OS may wish to let another process q use the CPU.
True or False: When a single image of a virtual machine is used as a source for multiple running guests, we call this templating.
True templating: In virtualization, using one standard virtual-machine image as a source for multiple virtual machines.
True or False: A context switch for a currently running process p may be caused by process p itself.
True This context switch may occur when process p requests a currently unavailable resource.
The invention of transistors marks the transition to the _____ generation of computer systems. A. 2nd B. 3rd C. 4th
A. 2nd Transistors replaced vacuum tubes, thus marking the transition from the 1st to the 2nd generation. The 3rd generation is associated with integrated circuits. The 4th generation is associated with microprocessors.
What best describes a maskable interrupt? A. An interrupt that can temporarily be disabled. B. An interrupt that must be responded to immediately, regardless what the operating system is performing at the moment. C. A technique for prioritizing various interrupts.
A. An interrupt that can temporarily be disabled. A maskable interrupt is one that can be ignored for as long as the interrupts corresponding to this mask are disabled. An interrupt that must be responded to immediately is known as a "non-maskable" interrupt, not a maskable interrupt
Which of the following is not considered a form of a system utility? A. Application programs B. Programming language support C. Background services
A. Application programs Although application programs such as web browsers, word processors, and spreadsheets may be supplied with an operating system, they are not considered system utilities that provide services on behalf of the operating system. Why is B wrong? Operating systems provide utilities for supporting developing programs such as compilers and debuggers. Why is C wrong? Several operating system utilities provide services that as supporting network communications that run in the background.
Which of the following typical OS types is associated with transistors? A. Batch OS B. Desktop and laptop OS C. Interactive multi-user OS D. OS for supercomputers, distributed systems, and mobile devices E. None
A. Batch OS Transistors made computers much smaller but also more expensive, requiring OS support to best utilize the scarce resources.
____ is/are not a technique for passing parameters from an application to a system call. A. Cache memory B. Registers C. Stack
A. Cache memory Cache is a form of high-speed memory and may contain any data. Cache is not a specific hardware or software data structure designed to hold specific data contents such as parameters to a system call. Why is B wrong? One of the techniques for passing parameters from a user application to a system call through hardware registers, however, this is uncommon. Why is C wrong? A stack is the most-common technique for passing parameters from a user application to a system call as it does not have any limitations to the length or number of parameters being passed.
What is the minimum number of physical CPUs an application consisting of 3 processes can utilize?
1 Each of the 3 processes can be time-shared on 1 physical CPU.
What is the maximum number of physical CPUs an application consisting of 3 processes can utilize?
3 Each of the 3 processes can run on a separate CPU.
An application consists of 3 processes. On how many virtual CPUs will the 3 processes run?
3 Each process can assume having a (virtual) CPU for itself.
