SCMP 391 – Homework 7

  1. What is the difference between the memory bus and the PCI bus?
  2. Calculate the bus bandwidth needed to display 1280 × 960) color video at 30 frames/sec. Assume that the data must pass over the bus twice, once from the CD- ROM to the memory and once from the memory to the screen.
  3. A computer has instructions that each require two bus cycles, one to fetch the instruction and one to fetch the data. Each bus cycle takes 10 nsec and each instruction takes 20 nsec (i.e., the internal processing time is negligible). The computer also has a disk with 2048 512-byte sectors per track. Disk rotation time is 5 msec. To what percent of its normal speed is the computer reduced during a DMA transfer if each 32-bit DMA transfer takes one bus cycle?
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