Assume a CPU with a fixed 32-bit instruction length has the following instruction forma
Assume a CPU with a fixed 32-bit instruction length has the following instruction format:
opcode mode [operand1] [operand2] [operand3]
The mode encodes the number of operands and each operand’s mode. For instance, one mode indicates three registers, another indicates two registers and an immediate datum, another indicates a main memory reference, etc. Assume there are 94 instructions and 22 modes. Answer the following.
a. One mode indicates three registers. How many registers can be referenced in this mode?
b. One mode indicates two registers and an immediate datum in two’s complement. Assuming there are 32 registers, what is the largest immediate datum that can be referenced?
c. One mode has a destination register and a source memory address (an unsigned
number). Assuming 16 registers, what is the largest memory reference available?
d. One mode has two memory addresses, both using base displacement. In both, the bases
are stored in index registers and the displacements are specified in the instruction.
Assuming we have 4 index registers, what is the largest displacement (displacements
are unsigned numbers)?
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