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| main component of computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level… “The one program running at all times on the computer” |
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| this is the initial program that runs when the computer is started up or rebooted (loads the os) |
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| Multiprocessor system that has two or more processors in close communication, and they share the computer bus and sometimes the clock, memory and peripheral devices. |
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| Ability to continue providing service proportional to the level of surviving hardware. |
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| Computer where multiple processor boards, I/O boards, and networking boards are placed in the same chassis. Difference from traditional computer and this is that this-processor board boots independently and runs its own operating system |
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| an approach to building a supercomputer as a cluster of commodity off-the-shelf personal computers, interconnected with a local area network technology like Ethernet, and running programs written for parallel processing |
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| increases CPU utilization by organizing jobs(code and data) |
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| The running of two or more programs or sequences of instructions simultaneously by a computer with more than one central processor. |
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| Ensures the proper execution of the operating system by 2 different executions: one based on operating system mode code and another on user mode code |
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| A register in the control unit of the CPU that is used to keep track of the address of the current or next instruction. Typically, the program counter is advanced to the next instruction, and then the current instruction is executed. Also known as a "sequence control register" and the "instruction pointer” |
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| a faster storage system in which information is copied to temporarily |
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| any mechanism for controlling the access of processes or users to the resources defined by the computer system |
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| defends a system from external and internal attacks |
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| a collection of physically separate, possibly heterogeneous, computer systems that are networked to provide the users with access to the various resources that the system maintains |
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| p. Network operating system |
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| operating system that provides features such as file sharing across the network and that includes a communication scheme that allows different processes on different computers to exchange messages |
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| used to protect networks from security breaches |
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| use a time and scheduling algorithms to rapidly cycle processes through the CPU, giving each user a share of the resources… Today, traditional systems like this are uncommon |
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| s. Symmetric multiprocessing |
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Definition
| most common multiprocessor design, where all processors are considered peers and run independently of each other |
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| t. Asymmetric multiprocessing |
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| A multiple-processor type system, in which each processor is assigned a specific task. A master processor controls the system, and the other processors either look to the master for instruction or have predefined tasks. The master processor schedules and allocates work to the slave processors |
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Term
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| stands for non-uniform memory access, in which a CPU has faster access to some parts of main memory than to other parts |
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| Describe the goals of a Computer Operating System from the users view versus the system view. |
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Definition
| The goal of the user view is to maximize the work (or play) that user is performing. In this case, the operating system is designed for ease of use. From the system point of view the operating system is the program most intimately involved with the hardware. |
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Term
| Describe two reasons why secondary storage is needed in a computer system.(2) |
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Definition
| One reason is that main memory is too small to store all the needed programs and data indefinitely, and the second reason is that main memory is a volatile storage that loses its contents when power is turned off or otherwise lost. |
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| Describe the main purpose of direct memory access relative to CPU utilization. (1) |
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Definition
| After the CPU writes the address of a command block to the direct-memory-access controller, it then goes on with other work. The DMA controller then proceeds to operate the memory bus directly, placing addresses on the bus to perform transfers without the help of the main CPU. |
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| Describe the three main advantages of a multiprocessor system.(3) |
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Definition
| The three main advantages are increased throughput, economy of scale, and increased reliability. |
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Term
| Discuss the difference between asymmetric and symmetric clustering. (1) |
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Definition
| Asymmetric mode: On this mode, one machine will be in hot stand-by mode (machine that only monitors the active server), while the other is running the applications. In case of server failure, the hot stand-by computer becomes the server.Symmetric mode: Two or more hosts are running in applications and are monitoring each other. This mode is more efficient since it uses all of the available hardware. |
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| Discuss what causes the situation called cache coherency. (1) |
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Definition
| When depending on a DMA, data is moving all the time and may be stored in multiple temporary locations. The problem with this is that when the computer is asked to access information, it may not access the most recent information. |
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Term
| Describe three issues that must be considered when using a handheld system. (3) |
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| Because of their size, handheld devices have small amounts of memory, slow processors, and small display screens. |
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| provides an interface to the services made available by an operating system |
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| text based program whose main function is to get and execute the next user-specified command |
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| c. GUI (Graphical User Interface) |
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| allows users to interface with the operating system |
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| a system program designed to aid the programmer in finding and correcting bugs |
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Term
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| specifies a set of funtions that are available to an application programmer, including the parameters that are passed to each function and the return values the programmer can expect |
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| a batch-system concept, it is a command to manage the execution of a process |
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Term
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Definition
| generates the system by reading a given file, or asks the operator of the system for information concerning the specific configuration of the hardware system, or probes the hardware directly to determine what components are there |
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Definition
| used to denote various forms of instruction sets designed for efficient execution by a software interpreter as well as being suitable for further compilation into machine code |
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| The services and functions provided by an operating system can be divided into two main categories. Briefly describe the two categories and discuss how they differ |
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Definition
| Two main are providing an interface to hardware and providing isolation between processes. The services are used more to help the user and the functions are used so the computer runs more efficiently. |
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| List five services provided by an operating system that are designed to make it more convenient for users to use the computer system. (5) |
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Definition
| User interface, program execution, I/O operations, file-system manipulation, error detection |
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Term
| Describe three general methods for passing parameters to the operating system. (3) |
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Definition
| Pass parameters in registers, registers pass starting addresses of blocks of parameters, parameters can be placed, or pushed, onto the stack by the program, and popped off the stack by the operating system. |
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Term
| What is the purpose of the command interpreter and why is it separate from the kernel? (2) |
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Definition
| It reads the commands from the user or from a file of commands and executes them, usually by turning them into one or more system calls. The command interpreter is subject to changes and this is why it is usually not part of the kernel. |
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Term
| What are the two models of interprocess communication? What are the strengths and weaknesses of the two approaches? (2) |
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Definition
| One is message passing and its strength is that the message can be exchanged between the processes either directly or indirectly through a common mailbox. Its weakness is that it is slower than the other model, which is the shared memory model. The shared memory model’s strength is in its ability to allow maximum speed and convenience of communication. The weakness, however, lies in its protection and synchronization between the processes. |
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| Why is the separation of mechanism and policy desirable? (1) |
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Definition
| To ensure that systems are easy to modify. With mechanism and policy separate, the policy may be changed at will while the mechanism stays unchanged. This arrangement provides a more flexible system. |
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Term
| Who originated the GUI concept? (1) |
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Definition
| First appeared due in part to research taking place in the early 1970s at Xerox PARC research facility |
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Term
| How is using the API functions better than using a system call? (1) |
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Definition
| It is easier for the user and less easy to mess up the operating system. |
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Term
| How can a programmer invoke a system call from a JAVA program? (1) |
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Definition
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Term
| What is the layered approach to OS architectural design? (1) |
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Definition
| os is broken down into layers, layer 0 is hardware and the highest layer (n) is user interface |
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Term
| What is the main advantage of the microkernel approach to system design? (1) |
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Definition
| Easier to a extend a microkernal, easier to port the operating system to new architectures, more reliable (less code running in kernal mode), more secure |
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Term
| How do user programs and system services interact in a microkernel architecture? (1) |
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Definition
| The programs and the services interact indirectly by exchanging messages with the microkernel. |
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Term
| What are the disadvantages of using the microkernel approach? (1) |
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Definition
| Microkernels can suffer from performance decreases due to increased system function overhead. |
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Term
| In what ways is the modular kernel approach similar to the layered approach? |
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Definition
| The modular kernel approach is usually organized around a core kernel with several types of loadable kernel modules. This resembles the layered approach. |
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Term
| In what ways do the modular and layer approach differ? (1) |
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Definition
| The layer approach imposes a strict ordering of subsystems. Subsystems at the lower layers are not allowed to invoke operations corresponding to upper-layer subsystems. Modular does not have constrictions and are allowed to invoke each other without any constraints. |
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Term
| What is the main advantage for an operating-system designer in using a virtual-machine architecture? (1) |
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Definition
| Prevents the system from errors |
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Term
| Discuss the design goals of an OS from the user and system perspective. (1) |
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Definition
| From the user perspective the system should be easy and convenient to learn and use, should be reliable, safe, and fast. From the system perspective it should be easy to design, implement, design, and it should be flexible, reliable, error free, efficient. |
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Term
| What is the structural problem of MS-DOS in respect to user applications? (1) |
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Definition
| Doesnt protect user programs, and its interfaces and level of funtionality are not well separated |
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Term
| During system generation, what information must be obtained in order to configure the OS for installation or during installation? (1) |
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Definition
| What cpu is used, how will the boot disk be formatted, how much memory will be available, what devices are available, what operating system options are desired. |
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| What organization is credited with originating the virtual-machine concept in OS design? (1) |
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Definition
| IBM (International Business Machine Corporation) |
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Term
| What are the three essential components of the Java technology? (3) |
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Definition
| Programming language specification, application programming interface(API), virutal machine specification |
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