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OS Tutorial 1 Flashcards
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- 1What are the three main purposes of an operating system?1. Provides an environment for the user to execute programs on computer conveniently and efficiently
2. To allocate the separate resources of the computer as needed to sole the problem given. This should be done as fairly as possible.
3. As a control program, the OS serves two major functions: (1) to supervise the execution of user programs to prevent errors or improper use, (2) manage and control I/O devices [think, what's happening internally, and externally] - 2List the four steps necessary to run a program on a completely dedicated machine.1. Reserve machine time (this is a mystery term)
2. Manually load the program onto memory
3. Load starting address and begin execution
4. Monitor and control execution of a program from the console - 3Describe the Batch Operating SystemThe users of a batch operating system do not interact with the computer directly. Each user prepares his job on an off-line device like punch cards and submits it to the computer operator.
To speed up processing, jobs with similar needs are BATCHED together and run as a group. The programmers leave their programs with the operator and the operator then sorts the programs with similar requirements into batches. - 4Describe the Interactive Operating SystemAn interactive operating system is one that allows the user to directly interact with the operating system whilst one or more programs are running. There will be an user interface in place to allow this to happen. It could be a command line style of interface or it could be a graphical interface.
- 5Describe a Time-Sharing Operating SystemAllows multiple users to use the same CPU. The CPU switches rapidly from one user to another. Instead of having a job defined by spooled card images, each program reads its next control card from the terminal,
- 6Distributed Operating SystemSystem distributes computation among several physical processors. Rather than sharing a clock or memory, each has it's own memory and communicates through communication lines like busses or LANs.
- 7What are the main differences between operating systems for mainframe computers and personal computers?Operating systems for batch (mainframe) systems have simpler requirements than for personal computers: they don't have to interact with them, therefore response time is a much bigger issue for Personal computers.
Personal computers will also need to switch between multiple jobs, but batch systems may not have this requirement. - 8How does the distinction between monitor mode and user mode function as a rudimentary form of a protection / security system?It enforces protection of critical resources, as the certain instructions and hardware access can only occur when the CPU is in kernel mode, as well as controlling when interrupts are enabled or disabled. The CPU has limited capacity in user mode, thus providing protection.
- 9What are the differences between a trap and an interrupt?A trap is a software generated interrupt which can be used to call OS routines or catch arithmetic errors.
An interrupt (in general) can be hardware generated, signalling the completion of I/O to remove the need for polling. - 10Which of the following actions should be privileged (i.e. executed only in privileged mode): a. set value of the timer b. read the clock c. clear memory d. Turn off interrupts e. Switch from user to kernel modea. set value of the timer
c. clear memory
d. Turn off interrupts - 11Give two reasons why caches are useful. What problems do they cause? Why not just have a cache as large as a disk?Useful for two reasons:
1. SPEED in general
2. Buffer in caches are useful when two components are exchanging data at different speeds. The larger the buffer, the more the faster component can 'get ahead'.
Problems: cache data needs to be consistent with corresponding data on the components. If which piece of data changes on the components which is also kept on the cache, it must change to match. These can be a problem when the same piece of data is used by two processors in a multi-processor system.
A cache can replace a component of the same size, as long as (1) it saves state, and (2) is affordable (lol, good luck) - 12Name three hardware aids for writing an operating system that can operate without interference from malicious or undebugged user programs?a. Monitor/user mode
b. privileged instructions
c. clock
d. memory protection
(No explanation given :eyeroll: ) - 13What are the major activities of an operating system in regard to process management?1) The creation and deletion of user and system processes
2) Suspending and resuming processes
3) - 5): Providing mechanisms for process synchronisation (3) and communication (4), and for deadlock handling (5). - 14What are the major activities of an operating system in regard to memory management?1) Keep track of which parts of memory are being used and when
2) Decide which processes are to be loaded into memory when space is available
3) Allocate and de-allocate memory space as needed. - 15What are the major activities of an operating system in regard to secondary-storage management?(1) Free-space management
(2) Storage allocation
(3) Disk scheduling - 16What are the major activities of an operating system in regard to file management?Creating and deleting files, opening, writing, re-positioning, etc.
- 17What are the main purposes of system calls and programs?To allow user-level processes to request services from the OS.
System programs can be thought of as bundles of useful system calls that provide basic functionality so that user's don't have to manually do stuff themselves. - 18What are the main advantages of the layered approach?Similar to the benefits of modular design (as modules can't spread across layers):
-- Easier to debug and modify
-- Information is kept only where it's needed
-- Bugs or misinformation are limited to a particular area - 19What are the main advantages of the separation of mechanism and policy?Mechanism and policy should be separate to make systems easy to modify. System installations are different so the mechanism is also different, but the policy (describing WHAT the system does) can still remain the same. Provides a more flexible system (how?)
- 20What are the main advantages of virtual-machine architecture?Allows many different operating systems to run on one system, allowing better research for different OSs. Also ensures security issues are contained, and bugs can easily be fixed (how?)
- 21—
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- Operating Systems Karteikarten am OS Tutorial 1 Flashcards, erstellt von Joel Pearson am 30/10/2018.
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