s − single instruction execution, enters subprocedures
S − single instruction execution, steps over subprocedures [ count ]
[ count ] and allow single instruction execution of client code. executes a single instruction. executes a single instruction except when that instruction is a or instruction, in this case, executes all instructions of the subprocedure until the procedure returns to the site of the or will fail to regain control if the subprocedure does not return. Both and may optionally take a count, which causes that count of instructions to be stepped. For both the or commands, branch instructions and the following instruction in the branch delay slot are considered "atomic" and a single step executes both instructions. brk(1spp), unbrk(1spp), c(1spp)