RISC-V and RISC Zero

Motion's primary VM

RISC Zero is a zero knowledge virtual machine based on the RISC-V instruction set. As a blockchain VM, RISC-V's most notable difference from the EVM instruction set is that it's register-based and not stack-based. Additionally: RISC stands for Reduced Instruction Set Computer, meaning RISC-V has a smaller amount of potential operations.

The design challenges section of Scroll's zkEVM blog post better covers the implications here. You'll notice that, from the jump, the second to fourth points already don't apply to RISC-V, the first and sixth impact RISC-V to a lesser extent, and Motion's architecture mitigates the fifth.

Without going too heavily into technical details, the above give a RISC-V zkVM key advantages over its counterparts:

1. Lower system requirements: a RISC machine can operate while keeping track of less information. This is ideal for a proving system because less complexity = lower constraint count = less memory and CPU overhead per frame and a wider pool of potential provers.

2. Less specialized development: RISC-V is a general use architecture; a network using it inherits R&D from a much wider development community. For instance, developer tools like disassemblers, debuggers, compilers, and toolchains already work today. There's very little, if any, catch-up to play on technical maturity.