Currently all data we work with is in words (32-bit blocks):
.Each register is a word.
.lw and sw both access memory one word at a time.
So how do we represent instructions?
.Remember: Computer only understands 1s and 0s, so “add $t0,$0,$0”
is meaningless.
.MIPS wants simplicity: since data is in words, make instructions
be words too
One word is 32 bits, so divide instruction word into “fields”.
Each field tells computer something about instruction.
We could define different fields for each instruction, but
MIPS is based on simplicity, so define 3 basic types of instruction
formats:
R-format, I-format, or J-format
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