in or1-ab.h, it seems that div insn is lost. The other questions: 1. why bal and jal? it seems these two are the same. 2. it seems that no multiply-and-subtract insn. 3.you don't wanna use "multiply unsigned" multiplication? it seems that only the opcode doesn't specify it's a signed or unsigned multiplication. 4.you discard the data cache operation insn? 5.the sched insn? Best regards, Jimmy