INPUT & OUTPUT MANAGEMENT
• Managing input & output in Windows XP involves many operating system componets.
• User-mode processes interact with an enviroment subsystem and not directly with kernel-mode componets.
• The enviroment subsystem pass input & output request to the input & output manager,which interacts with devices drivers to handle such request.
• Sereval device drivers,organized into a driver stack,cooperate to fulfill an input & output request.
• The plug and play manager dynamicaly recognizes when new devices are added to the system and allocates and deallocates resources,such as input & output ports or DMA channels, to them.
• The power manger administers the operating system’s power mangement policy.
• The power policy detemines whether to power down devices to conserve energy or keep them fully powered for high responsiveness.
5.3 Elaborate the concept of buffering
• Buffer overflow weakness is one of the many disadvantages of this type of security computer
• Buffer overflow attacks occur when the excessive Attacker provide input on the plan on the run
• Buffee overflow results from the weakness of the programming language c, c + +, fortran, and assembly, which does not automatically check the limit input when the program is executed
• The program is so complex, sehinnga programmers themselves do not know the weaknesses of the program
• Relies on external data to control the program
• Buffer is provided at the memory allocation, such as arrays or pointers in C. in the language C and C + +, there is no automatic restrictions on buffernya, where users can write through the input buffer. For example:
int main () {
int buffer [10];
buffer [20] = 10;
}
• Program in C above is a valid program, and each compiler to compile without error
• A process is a program in execution.
5.4 Recognize spooling technique
• In computer science, spooling refers to a process of transferring data by placing it in a temporary working area where another program may access it for processing at a later point in time.
• The normal English verb "spool" can refer to the action of a storage device that incorporates a physical spool or reel, such as a tape drive.
• Spooling refers to copying files in parallel with other work.
• The most common use is in reading files used by a job into or writing them from a buffer on a magnetic tape or a disk.
• Spooling is useful because devices access data at different rates. The buffer provides a waiting station where data can rest while the slower device catches up.
• This temporary working area would normally be a file or storage device.
• The most common spooling application is print spooling: documents formatted for printing are stored onto a buffer (usually an area on a disk) by a fast processor and retrieved and printed by a relatively slower printer at its own rate.
• Spooler or print management software may allow priorities to be assigned to jobs, notify users when they have printed, distribute jobs among several printers, allow stationery to be changed or select it automatically, generate banner pages to identify and separate print jobs, etc.
• The temporary storage area to which E-mail is delivered by a Mail Transfer Agent and in which it waits to be picked up by a Mail User Agent is sometimes called a mail spool
5.1 Explain on input-output management
• In economics, an input-output model uses a matrix representation of a nation's (or a region's) economy to predict the effect of changes in one industry on others and by consumers, government, and foreign suppliers on the economy
• Input-output depicts inter-industry relations of an economy. It shows how the output of one industry is an input to each other industry
• most uses of the input-output analysis focuses on the matrix set of interindustry exchanges, the actual focus of the analysis from the perspective of most national statistical agencies, which produce the tables, is the benchmarking of gross domestic product
• The mathematics of input-output economics is straightforward, but the data requirements are enormous because the expenditures and revenues of each branch of economic activity have to be represented
