RISC-V Architecture Question & Answers January 31, 2026 By WatElectronics RISC-V is a modern, open-standard Instruction Set Architecture (ISA) that has rapidly gained adoption across academia, industry, and research due to its simplicity, modularity, and openness. Unlike proprietary ISAs, RISC-V allows designers, researchers, and students to freely study, implement, and extend the architecture, making it an ideal platform for learning computer architecture and experimenting with processor design. This collection of 100 Multiple Choice Questions (MCQs) on RISC-V Architecture is carefully designed to test not only basic conceptual understanding, but also deeper architectural insights. The questions cover a wide range of topics including the base integer ISA, instruction formats, load-store architecture, control flow, extensions (M, A, F, D, C, V, K, etc.), privilege modes, Control and Status Registers (CSRs), pipeline considerations, and design philosophy of RISC-V. Each question is accompanied by four options, a useful hint, and a clear explanation to help learners understand why a particular answer is correct. Many questions are intentionally slightly tricky, reflecting the type of thinking required in competitive exams, technical interviews, university assessments, and research discussions. This MCQ set is suitable for: Undergraduate and postgraduate students studying Computer Architecture. GATE / university exam aspirants. Embedded systems and processor design engineers. Researchers and self-learners exploring RISC-V. By working through these questions, readers can strengthen their conceptual foundation, identify knowledge gaps, and develop a more practical and architectural understanding of RISC-V beyond rote memorization. 1). What is the primary reason RISC-V is described as an “open” ISA? It has fewer instructions It is royalty-free and openly specified It only supports open-source CPUs It is simpler than ARM None Hint 2). Which part of RISC-V ensures long-term software compatibility? Microarchitecture Privileged specification Base ISA stability Compiler optimizations None Hint 3). What does “RV64I” indicate? 64-bit registers with integer base ISA 64 instructions 64-bit floating point 64-bit compressed instructions None Hint 4). Which register is hard-wired to zero in RISC-V? x31 x1 x0 sp None Hint 5). How many general-purpose registers does RISC-V define? 16 24 32 64 None Hint 6). Why is the instruction length fixed at 32 bits in the base ISA? To reduce memory usage To simplify decoding To increase instruction density To match ARM None Hint 7. Which extension adds multiplication and division instructions? F A M C None Hint 8). What happens if an implementation omits the M extension? The CPU becomes non-RISC-V compliant Software must emulate multiply/divide The compiler fails Floating point is disabled None Hint 9). Which instruction format is used by ADD? I-type S-type R-type U-type None Hint 10). Which field distinguishes ADD from SUB? Opcode funct3 funct7 rd None Hint 11). Why does RISC-V not include branch delay slots? A. Compiler inefficiency Pipeline complexity Simplicity and cleaner semantics Performance loss None Hint 12). What is the alignment requirement for RISC-V instructions? 1 byte 2 bytes 4 bytes 8 bytes None Hint 13). Which instruction is used for unconditional jumps? BEQ JAL JALR AUIPC None Hint 14). Why does JALR clear the least significant bit of the target address? Security Alignment enforcement Pipeline hazard avoidance Instruction compression None Hint 15. Which branch instruction compares signed values? BLTU BGEU BLT BEQ None Hint 16). Why is RISC-V called a load-store architecture? Only load instructions exist Memory is accessed only via loads/stores All instructions access memory No registers are used None Hint 17). Which instruction loads a signed byte? LBU LH LB LW None Hint 18). What happens on misaligned memory access in RISC-V? Always allowed Always ignored Traps or handled by hardware Converted to aligned access None Hint 19). Which instruction stores a word? SH SB SW SD None Hint 20). Why are immediate values sign-extended in most instructions? Simpler hardware Larger range Faster execution Compiler convenience None Hint 21). What is the purpose of the C extension? Cryptography Compressed instructions C language support Cache control None Hint 22). Which extension enables atomic operations? A M F D None Hint 23). Why are extensions optional in RISC-V? To increase fragmentation To allow scalable designs To reduce compiler complexity To remove backward compatibility None Hint 24). Which extension supports single-precision floating point? D Q F M None Hint 25). What does “Z” signify in RISC-V extensions? Experimental Deprecated Standard but optional Vendor-specific None Hint RISC-V Architecture MCQs for Exams 26). How many privilege modes does RISC-V define (standard)? 2 3 4 5 None Hint 27). Which mode has full hardware control? User Supervisor Hypervisor Machine None Hint 28). Which register holds trap cause information? mtvec mepc mcause mscratch None Hint 29). Why is Supervisor mode optional? To simplify OS design For embedded systems For backward compatibility For virtualization None Hint 30). What does mtvec store? Trap return address Interrupt enable bits Trap handler base address Stack pointer None Hint 31). Why does RISC-V avoid condition codes (flags)? Slower execution More instructions Better pipelining Reduced instruction set None Hint 32). Which instruction can act as a NOP? ADD x0, x0, x0 SUB x0, x0, x0 AND x0, x0, x0 All of the above None Hint 33). Why is AUIPC useful? Absolute addressing PC-relative addressing Stack manipulation Function calls None Hint 34). What makes RISC-V suitable for deep pipelines? Few instructions No microcode Simple decode and no flags High clock speed None Hint 35). Which hazard is most reduced by load-store design? Structural Control Data Memory aliasing None Hint 36). What enables formal verification in RISC-V? Fewer instructions Open specification Fixed registers Modular extensions None Hint 37). Why does RISC-V support variable instruction lengths? Performance Power savings Code density Compiler simplicity None Hint 38). What distinguishes RISC-V from ARM at ISA level? Pipeline depth Instruction encoding freedom Endianness Cache coherence None Hint 39). Why is there no dedicated stack instruction? Inefficient Compiler handles stack Hardware complexity Legacy reasons None Hint 40). Which feature helps RISC-V scale from IoT to HPC? Fixed instruction count Open governance Modular ISA Single privilege mode None Hint 41). Which register conventionally holds the return address in RISC-V? x0 x1 x2 x10 None Hint 42). Which instruction uses the U-type instruction format? ADD JAL LUI BEQ None Hint 43). Which RISC-V extension supports double-precision floating-point operations? F D Q M None Hint 44). Why does RISC-V allow flexibility in endianness? To increase performance To simplify compilers For system integration flexibility To reduce instruction size None Hint 45). What prevents undefined instruction behavior in RISC-V? Compiler checks Hardware exceptions Fully specified instruction encodings Privileged modes None Hint 46). Which CSR primarily controls global interrupt enable bits? mtvec mcause mstatus mepc None Hint 47). What does XLEN represent in RISC-V? Instruction length Address width Register width Cache line size None Hint 48). Which instruction is commonly used for PC-relative function calls? JAL JALR AUIPC BEQ None Hint 49). Why does RISC-V avoid microcode? To reduce power consumption To simplify hardware design To improve compatibility To support legacy systems None Hint 50). Which extension adds bit-manipulation instructions? M B K C None Hint RISC-V Architecture MCQs for Interviews 51). What is the primary purpose of the mscratch register? Stack pointer Interrupt vector Temporary storage during traps Debugging None Hint 52). Why are immediates split across instruction fields? Performance reasons Security reasons Encoding efficiency Compiler limitation None Hint 53). Which instruction returns from a machine-mode exception? SRET URET MRET RET None Hint 54). Which privilege mode typically runs the bootloader? User Supervisor Hypervisor Machine None Hint 55). Which CSR stores the program counter of the trapped instruction? mcause mtvec mepc mstatus None Hint 56). Why does the base RISC-V ISA not include SIMD instructions? Complexity Low performance Optional specialization via extensions Compiler issues None Hint 57). What is the name of the RISC-V vector extension? B V P K None Hint 58). Why is RISC-V attractive for academic research? Fewer instructions High clock speed Custom extension support Smaller binaries None Hint 59). Which instruction loads an unsigned half-word? LH LHU LW LB None Hint 60). Why is the privileged specification separated from the base ISA? To reduce hardware cost To simplify OS development To keep ISA minimal and scalable To improve security None Hint 61). Which instruction supports PC-relative address calculation without branching? JAL AUIPC LUI ADDI None Hint 62). Why are branch offsets limited in size? Performance reasons Pipeline constraints Instruction encoding width Compiler limitations None Hint 63). Which extension enables virtualization support? S V H N None Hint 64). What does a WAR (Write After Read) hazard indicate? Structural conflict Instruction dependency Memory collision Control hazard None Hint 65). Which register is conventionally used as the stack pointer? x1 x2 x8 x10 None Hint 66). Why is the ABI kept separate from the ISA? To reduce hardware complexity To allow software evolution To improve execution speed To enable virtualization None Hint 67). Which instruction uses the S-type format? LW ADD SW BEQ None Hint 68). Why are most branches PC-relative in RISC-V? Faster execution Easier relocation Reduced power Better caching None Hint 69). Which extension introduces cryptographic instructions? B V K M None Hint 70). Why is RISC-V especially suitable for teaching computer architecture? Small register file Minimal legacy complexity Fewer instructions High performance None Hint 71). What defines whether an instruction encoding is legal? Compiler support Hardware implementation ISA specification Privilege mode None Hint 72). Why is register x0 particularly useful? Faster execution Hardware optimization Always contains zero Used for interrupts None Hint 73). Which instruction performs an unsigned comparison? BLT BGE BLTU BEQ None Hint 74). Why does RISC-V use a fixed number of registers Simpler decoding Lower power Compiler optimization Memory efficiency None Hint 75). What part of the immediate does LUI ignore? Upper 20 bits Lower 12 bits Sign bit Opcode None Hint RISC-V Architecture MCQs for Quiz 76). Which privilege mode has the highest interrupt priority? User Supervisor Hypervisor Machine None Hint 77). Why are CSRs modular in RISC-V? Performance Security Scalability Backward compatibility None Hint 78). Which extension targets DSP-style workloads? V P B K None Hint 79). Why does RISC-V avoid branch delay slots? Performance Pipeline complexity Cleaner programming model Legacy support None Hint 80). Which instruction performs an indirect jump? JAL BEQ JALR AUIPC None Hint 81). Why is RISC-V suitable for hardware accelerators? High clock speed Simple pipeline Custom ISA extensions Fixed instruction size None Hint 82). Which register is conventionally used as the global pointer? x1 x2 x3 x4 None Hint 83). What is special about the RV32E variant? 64-bit registers Embedded focus with fewer registers No floating-point support No privilege modes None Hint 84). Why are memory accesses explicit in RISC-V? Security Predictability Performance Compatibility None Hint 85). Which extension supports quad-precision floating point? D Q F V None Hint 86). Why is instruction fetch simpler in RISC-V? Fewer instructions Fixed base instruction length Smaller cache No branches None Hint 87). What ensures long-term binary compatibility in RISC-V? Compiler design Frozen base ISA ABI stability Privileged spec None Hint 88). Which instruction is commonly used for bit masking? OR XOR AND ADD None Hint 89). Why is RISC-V considered vendor-neutral? Few instructions No microcode Open governance model Fixed pipeline None Hint 90). Which extension supports user-level interrupts? H S N K None Hint 91). Why are CSRs accessed using special instructions? Performance Security Uniform access model Legacy design None Hint 92). How is subtraction with an immediate performed in RISC-V? SUBI ADDI with negative immediate SUB XORI None Hint 93). Why does RISC-V avoid condition flags? Reduced instruction count Better compiler support Avoid hidden dependencies Lower power None Hint 94). How do compilers build large constants in RISC-V? Single ADDI LUI only LUI + ADDI AUIPC only None Hint 95). Why is RISC-V considered future-proof? High performance Fixed ISA Reserved extension space Simple pipeline None Hint 96). Which instruction loads an unsigned byte? LB LBU LH LW None Hint 97). Why are branch offsets signed? Performance Encoding simplicity To support backward branches Security None Hint 98). Which privilege mode typically runs user applications? Machine Supervisor Hypervisor User None Hint 99). Why does RISC-V separate integer and floating-point registers? Performance Simpler cores Better precision Compiler simplicity None Hint 100). What makes RISC-V a “clean-slate” architecture? Small instruction set No backward compatibility No legacy constraints Minimal registers None Hint Time's up
