A. An instruction set executes a single low-level operation.
B. The access calls to main memory are fewer as compared to RISC.
C. The instruction set supports all the low-level programming languages.
D. The programmer is explicitly required to call the loading and storing functions.
The correct answer is B.
The access calls to main memory in CISC are fewer than reduced instruction set computer (RISC).
Each instruction in CISC executes multiple low-level operations, such as an arithmetic operation, a memory load or a memory store. The instruction sets are complex, which in effect reduces the program size. The access calls to memory are also less than RISC because a single instruction set executes multiple operations. Therefore, small program sizes and fewer access calls to main memory are attributed to the compact size of the microprocessor instruction set architecture (ISA) in CISC. The complex instruction sets in CISC contribute to an adverse effect on the performance of the processor. The overhead of decoding the instructions also increases with the complexity of the instruction set.
CISC does not support all of the low-level programming languages.
The programmer in CISC is not required to explicitly call the loading and storing functions because the instructions directly operate on the processor’s memory. Motorola 68000 and CDC 6600 are examples of CISC processors.
When microcomputers were first developed, the instruction fetch time was much longer than the instruction execution time because of the relatively slow speed of memory accesses. This situation led to the design of CISC.
CISSP Question of the Week courtesy of Transcender Labs.