The process of using a cache is known as caching

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Unformatted text preview: sector address, reads the contents of the sector, and transfers the contents directly to main memory, without any intervention from the CPU (Figure 6.12(b)). This process where a device performs a read or write bus transaction on its own, without any involvement of the CPU, is known as direct memory access (DMA). The transfer of data is known as a DMA transfer. After the DMA transfer is complete and the contents of the disk sector are safely stored in main memory, the disk controller notifies the CPU by sending an interrupt signal to the CPU (Figure 6.12(c)). The basic idea is that an interrupt signals an external pin on the CPU chip. This causes the CPU to stop what it is currently working on and to jump to an operating system routine. The routine records the fact that the I/O has finished and then returns control to the point where the CPU was interrupted. Aside: Anatomy of a commercial disk. Disk manufacturers publish a lot of high-level technical information on their Web pages. For examp...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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