Consider a system employing interrupt-driven I/O for a particular device that trans- fers data at an average of 8 KB/s on a continuous basis. a. Assume that interrupt processing takes about 100 μs (i.e., the time to jump to the interrupt service routine (ISR), execute it, and return to the main program). De- termine what fraction of processor time is consumed by this I/O device if it inter- rupts for every byte. b. Now assume that the device has two 16-byte buffers and interrupts the processor when one of the buffers is full. Naturally, interrupt processing takes longer, be- cause the ISR must transfer 16 bytes. While executing the ISR, the processor takes about 8 us for the transfer of each byte. Determine what fraction of processor time is consumed by this I/O device in this case. c. Now assume that the processor is equipped with a block transfer I/O instruction such as that found on the Z8000. This permits the associated ISR to transfer each byte of a block in only 2 µs. Determine what fraction of processor time is con- sumed by this I/O device in this case.

Consider a system employing interrupt-driven I/O for a particular device that trans- fers data at an average of 8 KB/s on a continuous basis. a. Assume that interrupt processing takes about 100 μs (i.e., the time to jump to the interrupt service routine (ISR), execute it, and return to the main program). De- termine what fraction of processor time is consumed by this I/O device if it inter- rupts for every byte. b. Now assume that the device has two 16-byte buffers and interrupts the processor when one of the buffers is full. Naturally, interrupt processing takes longer, be- cause the ISR must transfer 16 bytes. While executing the ISR, the processor takes about 8 us for the transfer of each byte. Determine what fraction of processor time is consumed by this I/O device in this case. c. Now assume that the processor is equipped with a block transfer I/O instruction such as that found on the Z8000. This permits the associated ISR to transfer each byte of a block in only 2 µs. Determine what fraction of processor time is con- sumed by this I/O device in this case.

Systems Architecture

7th Edition

ISBN:9781305080195

Author:Stephen D. Burd

Publisher:Stephen D. Burd

Chapter4: Processor Technology And Architecture

Section: Chapter Questions

Problem 2PE: If a microprocessor has a cycle time of 0.5 nanoseconds, what’s the processor clock rate? If the...

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