ISA & Assembly

What is a characteristic of a load-store architecture such as RISC-V?

  1. AArithmetic instructions such as add read values directly from memory and write results back to memory
  2. BOnly load and store instructions access memory; arithmetic is done between registers
  3. CIt has no registers and computes by pushing all values onto a stack
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Answer: B. Only load and store instructions access memory; arithmetic is done between registers

In a load-store architecture, a memory value is first loaded into a register, arithmetic such as add or compare is done between registers, and results are written back to memory with a store if needed. Because arithmetic instructions never touch memory, instructions have a uniform shape and are easy to pipeline. This contrasts with designs like x86, where an arithmetic instruction such as "add eax, [mem]" can read memory.

  • A. Arithmetic instructions operating on memory is a CISC trait, as in x86.
  • B. Correct. Memory access is limited to loads and stores.
  • C. That is a stack machine, not a load-store design.
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More ISA & Assembly questions

  1. What is the property of register x0 (zero) in RISC-V?
  2. Which describes the general-purpose integer registers of RISC-V RV32I (the 32-bit base integer instruction set)?
  3. What is the relationship between assembly language and machine code?
  4. Which real instruction does the assembler use for the RISC-V pseudo-instruction "nop" (do nothing)?
  5. What is the difference between the RISC-V "add" and "addi" instructions?