MIPS R4000 Microprocessor User's Manual 15
Introduction
The instruction set can be further divided into the following groupings:
• Load and Store instructions move data between memory and
general registers. They are all immediate (I-type) instructions,
since the only addressing mode supported is base register plus
16-bit, signed immediate offset.
• Computational instructions perform arithmetic, logical, shift,
multiply, and divide operations on values in registers. They
include register (R-type, in which both the operands and the
result are stored in registers) and immediate (I-type, in which
one operand is a 16-bit immediate value) formats.
• Jump and Branch instructions change the control flow of a
program. Jumps are always made to a paged, absolute address
formed by combining a 26-bit target address with the high-
order bits of the Program Counter (J-type format) or register
address (R-type format). Branches have 16-bit offsets relative
to the program counter (I-type). Jump And Link instructions
save their return address in register 31.
• Coprocessor instructions perform operations in the
coprocessors. Coprocessor load and store instructions are
I-type.
• Coprocessor 0 (system coprocessor) instructions perform
operations on CP0 registers to control the memory
management and exception handling facilities of the processor.
These are listed in Table 1-18.
• Special instructions perform system calls and breakpoint
operations. These instructions are always R-type.
• Exception instructions cause a branch to the general exception-
handling vector based upon the result of a comparison. These
instructions occur in both R-type (both the operands and the
result are registers) and I-type (one operand is a 16-bit
immediate value) formats.
Chapter 2 provides a more detailed summary and Appendix A gives a
complete description of each instruction.
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