OS A program that manages the computers hardware an provides the environment in
which programs are executed
- its a resource allocator and control program
CPU The processor that performs the computations
I/O devices Items such as the terminal, disks, video board, printer, network card key are a...
WGU C191 MODULE 1 Latest Update Graded A OS ✔✔A program that manages the computers hardware an provides the environment in which programs are executed - its a resource allocator and control program CPU ✔✔The processor that performs the computations I/O devices ✔✔Items such as the terminal, disks, video board, printer, network card key are all considered one of these Main Memory ✔✔This contains data and programs used by the CPU System bus ✔✔This is the communication medium between CPU, memory and peripherals kern el ✔✔the one program running at all times on the computer - everything else is system or application program Kernel Mode ✔✔When the OS has control of the computer rather than the user, it is in what mode? Privileged instructions ✔✔These instructions are restricted to use only by the OS and make it so that the user may not access , memory, halt the machine, disable and enable interrupts, or address I/O directly System Call ✔✔Provides interface to services made available by OS. Ca uses traps to allow the kernel to execute privileged instructions device controllers ✔✔connect through common bus providing access to shared memory - each controller is in charge of particular device type - each controller has local buffer - informs CPU that it has finished an operation by causing interrupt interrupt vector ✔✔which contains the addresses of all the service routines interrupt handling ✔✔1. The OS preserves the state of the CPU by storing registers and program counter. 2. Determines whi ch type of interrupt has occurred: polling/vectored. 3. Separate segments of code determine what action should be taken for each type of interrupt. traps ✔✔What do system calls cause? device status table ✔✔contains entry for each I/O device indicating its type, address, and state application programming interface ✔✔API direct memory access structure ✔✔Used for high -speed I/O devices able to transmit information at close to memory speeds clustered systems ✔✔- multiple systems working together - usually sharing storage via SAN - provides high availability service which survives failures - asymmetric and symmetric clustering - some clusters are for high performance computing(HPC) Asymmetric Clustering ✔✔one machine is in hot -standby mode while the other is running applications symmetric clustering ✔✔has multiple nodes running applications, monitoring each other caching ✔✔Important principle, performed at many levels in a computer (in hardware, opera ting system, software) Information in use copied from slower to faster storage temporarily Faster storage (cache) checked first to determine if information is there API - definition ✔✔Specifies a set of functions that are available to an application pr ogrammer, including the parameters that are passed to each function and the return values the programmer can expect Trap or Exception ✔✔Software generated interrupt. It causes the kernel to take over and initiate a process. Trap or Interrupt handler ✔✔This uses the parameter to the system call to jump to the appropriate handler( I/O, terminal etc) Register ✔✔A small set of data holding places that are part of the computer processor. It can hold an instruction, a storage address, or any kind of data 1. Text 2. Data 3. Stack ✔✔What are the 3 segments in a process? Accounting ✔✔This term is used in tracking usage statistics for users Communications ✔✔One process exchanging information with another process Error Detection ✔✔The process by which an operating system detects and responds to errors
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