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?