Operating Systems Chapter 1 Review

What is a network and give 3 examples of networks.

- A network is a communications path. 1. Local Area Network (LAN) 2. Wide Area Network (WAN) 3. Metropolitan Area Network (MAN)

What are magnetic disks?

- Rigid metal or glass platters covered with magnetic recording material.

What are the 3 components that the I/O subsystem is responsible for?

1. Memory management of I/O including: buffering (storing data temporarily while it is being transferred), caching (storing parts of data in faster storage for performance purposes), and spooling (the overlapping of output of one job with input of other jobs). 2. General device-driver interface 3. Drivers for specific hardware devices.

What group created Open Source OS?

Free Software Foundation (FSF)

What is timesharing (multitasking) and what type of scheduling does it use?

- Timesharing is a logical extension in which CPU switches jobs frequently so that users can interact with each job while it is running. - Response time should be less than a second. - Each user has at least one program executed in memory. - CPU scheduling allows several jobs to be run at the same time. - Virtual memory allows execution of processes not completed in memory.

What do users want out of an OS and what do most users not really care about?

- Users want convenience (ease of use) - Users don't care about resource utilization

What does dual mode allow an OS to do?

- allows OS to protect itself and other system components.

What is caching?

- copying information into faster storage system; main memory can be viewed as cache for a secondary storage.

Clustered systems share storage via a storage-area network (SAN). T/F?

True

Handheld devices and mobile computers are resource poor. T/F?

True

What is the one program that is running at all times on a computer?

The Kernel

What are the 3 main OS activities regarding Mass-Storage management?

- Free space management - Storage allocation - Disk scheduling

What are clustered systems often used for?

- High-performance computing (HPC) - Applications must be written to use parallelization.

What is distributed computing?

- A collection of separate, possibly heterogeneous, systems networked together.

What is a process?

- A process is a program in execution.

In terms of interrupts, what is a trap?

- A software-generated interrupt caused either by an error or a user request.

Describe P2P computing

- All nodes are considered peers - each node may act as a client, server, or both - node must join P2P network.

What is the difference between multiprocessor systems and clustered systems?

- Clustered systems are similar to multiprocessor systems, but they constitute multiple systems working together.

What is the function of a disk controller?

- Determines the logical interaction between the device and the computer.

How is client-server computing structured?

- Dumb terminals supplanted by smart PCs - Many systems now servers, responding to requests generated by clients - Compute-server: provides an interfaact to client to request services. - File-server: provides interface for clients to store and retrieve files

What is secondary storage?

- Extension of main memory that provides large nonvolatile storage capacity.

What happens if the cache is checked for info. and the info is found in the cache? What happens if the info. is not found in the cache.

- If the info. is found in the cache, it is used directly from the cache (quick and easy) - If the info. is NOT found in the cache, info. is copied to the cache and then used.

How is a lost interrupt prevented?

- Incoming interrupts are disabled while another interrupt is being processed.

What is the purpose of a bootstrap program (2 answers)?

- Initializes all aspects of the system - Loads the Operating System kernel and starts execution.

What is the function of an interrupt?

- Interrupts transfer control of the interrupt service routine through the interrupt vector (contains addresses of all service routines).

Why is multiprogramming useful and what type of scheduling does multiprogramming use?

- It is needed for efficiency. - A single user cannot keep CPU and I/O devices busy at all times. - organizes jobs (code and data) 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, OS switches to another job

When does the bootstrap program load and where is it typically stored?

- Loaded at power-up or reboot. - Typically stored in ROM or EPROM, generally known as firmware.

What are the purposes of network operating systems?

- Network operating systems provide features between systems across networks. - Communication scheme allows systems to exchange messages - Illusion of a single system

What does a typical Computer System Organization structure look like?

- One or more CPU's, device controllers, I/O devices connected through a common bus providing access to shared memory. - Concurrent execution of CPU's and devices competing for memory cycles.

What are Open-Source Operating Systems?

- Operating Systems made available in source-code format rather than just binary closed-source

What is included in tertiary storage?

- Optical storage - Magnetic tapes

What does the typical computing environment for an office look like?

- PCs connected to a network, terminals attached to mainframe or minicomputers providing batch and timesharing. - Now portals allowing networked and remote system access to the same resources.

What are the roles of protection and security in regards to an OS?

- Protection: any mechanism for controlling access of processes or used to resources defined by the OS - Security: defense of the system against internal and external attacks.

What modes constitute "dual mode" and what is the purpose of these modes?

- Provides ability to distinguish when system is running user code or kernel mode. - Some instructions are designated as privileged and are only executable in kernel mode. - System call changes mode to kernel, return from call resets it to user.

What is the difference between a single threaded process and a multi-threaded process?

- Single-threaded process has one program counter specifying the location of next instruction to execute. Also, processes are executed SEQUENTIALLY, one at a time, until completed. - Multi-threaded process has one program counter per thread.

What are special purpose systems and give a couple examples.

- Special purpose systems are real-time embedded systems and are the most prevalent form of computers. - Multimedia systems which have streams of data that must be delivered according to time restrictions. - Handheld systems such as PDA's and smart phones. They have limited CPU, memory, and power. Also, reduced OS and limited I/O

What are the other operating system programs considered to be (excluding the kernel)?

- System Programs (Ships with the OS) - Application Programs

What is the entire speed of computer operation dependent on?

- The disk subsystem and its algorithms

Describe the transition from User to Kernel mode.

- There is a timer to prevent infinite loop/ process hogging resources. 1. set interrupt after specific period 2. Operating system decrements counter 3. when counter reaches zero, an interrupt is generated. 4. set up before scheduling process begins to regain control or terminate program that exceeds allotted time.

What is the purpose of Direct Memory access?

- Used for high-speed I/O devices able to transmit information at close to memory speeds. - Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention. - One interrupt generated per block.

What is an Operating System?

-A program that acts as an intermediary between a user of a computer and the computer hardware.

What are some examples of Open Source OS?

-GNU/Linux -UNIX

What are the 2 types of multiprocessing?

1. Asymmetric Multiprocessing 2. Symmetric Multiprocessing

What are the 5 process management activities that the Operating System is responsible for?

1. Creating and deleting both user and system processes. 2. Suspending and resuming processes. 3. Providing mechanisms for process synchronization. 4. Providing mechanisms for process communication. 5. Providing mechanisms for deadlock handling.

What are the 4 main OS activities regarding storage management?

1. Creating and deleting files and directories 2. Primitives to manipulate files and dirs 3. Mapping files onto secondary storage 4. Backup files onto stable (non-volatile) storage media.

What are the 3 goals of an Operating System?

1. Execute User Programs and make solving user problems easier. 2. Make the computer system convenient to use. 3. Use the computer hardware in an efficient manner.

What are the 4 components of a computer system? Provide a definition + example for each.

1. Hardware - provides basic computing resources (CPU, memory, I/O devices) 2. Operating System - Controls and coordinates use of hardware among various applications and users. 3. Application Programs - Defines the ways in which system resources are used to solve computing problems of users. (Word processors, compilers, web browsers, database system, video games). 4. Users - People, machines, other computers...

What are the 6 parts of the computer-system operation?

1. I/O devices and the CPU can execute concurrently. 2. Each device controller is in charge of a particular device type. 3. Each device controller has a local buffer. 4. CPU moves data from/to main memory to/from local buffers. 5. I/O is from the device to local buffer of controller. 6. Device controller informs CPU that it has finished its operation by causing an interrupt.

What are the 3 main OS activities regarding memory management?

1. Keeping track of which parts of memory are currently being used and by whom. 2. Deciding which processes (or parts thereof) and data to move into and out of memory. 3. Allocating and deallocating memory space as needed.

The OS serves as a ____________ and a _____________.

1. Resource allocator: manages all resources and decides between conflicting requests for EFFICIENT and FAIR resource use. 2. Control Program: controls execution of programs to prevent errors and improper use of the computer.

What are 3 advantages of Multiprocessors? What are Multiprocessors also known as?

Advantages: 1. Increased throughput 2. Economy of Scale 3. Increased reliability. Multiprocessors are also known as parallel systems or tightly-coupled systems.

Differentiate asymmetric clustering from symmetric clustering.

Asymmetric clustering: has one machine in hot-standby mode. Symmetric clustering: has multiple nodes running applications and monitoring each other

What are usually used to store data that does not fit in main memory or data that must be kept for a long period of time?

Disks.

A program is an active entity and a process is a passive entity. T/F?

False. - Program = passive entity. - Process = active entity.

Operating systems are not interrupt driven. T/F?

False. Operating Systems ARE interrupt driven.

What does the storage-device hierachy look like from bottom to top (7 components).

Magnetic tapes(bottom)> Optical disk> Magnetic Disk> Electronic disk> Main Memory> cache> registers (top)

What is the only storage media that the CPU can access directly and describe this type of storage.

Main Memory. 1. Random Access 2. Typically volatile

What gaming system uses P2P servers?

Nintendo Switch -.-

Is there a universal definition for an Operating System?

No, it depends on the point of view.

Does Peer 2 Peer computing distinguish clients and servers?

No.

What does a process need to accomplish its tasks?

Resources: - CPU , memory, I/O, files... - Initialization data

In terms of caching, information in use is copied from slower to faster storage temporarily. T/F?

True

Multiprocessor environments must provide cache coherency in hardware such that all CPUs have the most RECENT value in their cache. T/F?

True