Question

Why are 31 registers considered a bad compromise instead of the 32 registers used by MIPS?

Answer 1

Why are 31 registers set considered as bad compromise rather than the 32 registers set used by MIPS:

Answer:

• Design principles say that “smaller is faster” but 31 register may not be significantly faster than 32 registers. Designer should desire more registers to keep the instruction clock cycle fast.

• Most of the MIPS instructions are of 32-bits. The MIPS instruction permits 5 bits to specify source and destination registers. 32 is the maximum number that can be represented by 5 bits. So, there is 32 register set.

• The 5 bit register fields $0 to $31 have given various name according to their usage where first register will always returns 0.

• MIPS is the RISC – reduced instruction set computer architecture that gives higher performance. It consists of 32 registers as the CPU actually has that many physical registers. Reducing the available registers to 31 means it will give slower RAM execution.