You
need not show the bit pattern for each instruction; just use the mnemonics listed, followed in each case
by the appropriate operand(s).
MOV 50, EDX // copy what??™s in 50 to the register
ADD 51, EDX // add what??™s in 51 to the register
MOV EDX, 101 // store the result in 101
3.10 What Intel x86 instructions would you use to accomplish subtraction using 2??™s complement addition?
This instruction set has a SUB instruction, but don??™t use that; write your own 2??™s complement routine
instead.
MOV 51, EDX // copy what??™s in 51 to the register
NEG EDX // take 2s complement of register
ADD EDX, 50 // subtract contents of 51 from 52
MOV EDX, 101 // store the result in 101
3.11 What are the advantages of a larger computer word size? Are there disadvantages? If so, what are the
disadvantages?
Advantages:
Easy to represent large numbers.
Easy to address large memory space.
Disadvantages:
Memory use is likely to be less ???bit-efficient??? when numbers are small.
Processors and supporting hardware are more expensive.
3.12 Assume that cache memory has an access time of 10 nanoseconds, while main memory has an access
time of 100 nanoseconds. If the ???hit rate??? of the cache is .70 (i.e., 70% of the time, the value needed is
already in the cache), what is the average access time to memory?
.
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