CSE 435- Final Exam Prep

Can be written out in batches problem 1 list and

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Unformatted text preview: s can be written out in batches. Problem 1 list and briefly define three techniques for performing I/O? Programmed I/O: The processor issues an I/O command, on behalf of a process, to an I/O module; that process then busy waits for the operation to be completed before proceeecling. Interrupt-driven I/O: The processor issues an I/O command on behalf of a process. There are then two possibilities. If the I/O instruction from the process is nonblocking, then the processor continues to execute instructions from the process that issued the I/O command. If the I/O instructions is blocking, hen the next instruction that the processor executes is from the OS, which will put the current process in a blocked state and schedule a another process. Direct memory access (DMA): A DMA module controls the exchange of data between main memory and an I/O module. The processor sends a request for the transfer of a block of data to the DMA module and is interrupted only after the entire block has been transferred. Problem 2 What is the difference between block-oriented devices and stream-oriented devices? Give a few examples of each? A block-oriented device stores information in blocks that are usually of fixed size, and transfers are made one block at a time. Generally, it is possible to reference data by its block number. Disks and USB keys are examples of block-oriented devices. A stream-oriented device transfers data in and out as stream of bytes, with no block structure. Terminals, printers, communications ports, mouse and other pointing devices, and most other devices that are not secondary storage are stream oriented....
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