Instruction Set Architecture and Design - Fundamentals of Computer Organization and Architecture - page 28

TABLE 2.4 Some Common Arithmetic Operations

Arithmetic operations Meaning

ADD Perform the arithmetic sum of two operands

SUBTRACT Perform the arithmetic difference of two operands

MULTIPLY Perform the product of two operands

DIVIDE Perform the division of two operands

INCREMENT Add one to the contents of a register

DECREMENT Subtract one from the contents of a register

DIVIDE instructions on their instruction set. Table 2.4 shows some common arith-
metic operations and their meanings.
Logical instructions are used to perform logical operations such as AND, OR,
SHIFT, COMPARE, and ROTATE. As the names indicate, these instructions per-
form, respectively, and, or, shift, compare, and rotate operations on register or
memory contents. Table 2.5 presents a number of logical operations.

2.3.3. Sequencing Instructions

Control (sequencing) instructions are used to change the sequence in which
instructions are executed. They take the form of CONDITIONAL BRANCHING
(CONDITIONAL JUMP), UNCONDITIONAL BRANCHING (JUMP), or CALL
instructions. A common characteristic among these instructions is that their
execution changes the program counter (PC) value. The change made in the PC
value can be unconditional, for example, in the unconditional branching or the
jump instructions. In this case, the earlier value of the PC is lost and execution of
the program starts at a new value specified by the instruction. Consider, for example,
the instruction JUMP NEW-ADDRESS. Execution of this instruction will cause the
PC to be loaded with the memory location represented by NEW-ADDRESS
whereby the instruction stored at this new address is executed. On the other hand,

TABLE 2.5 Some Common Logical Operations

Logical operation Meaning

AND Perform the logical ANDing of two operands

OR Perform the logical ORing of two operands

EXOR Perform the XORing of two operands

NOT Perform the complement of an operand

COMPARE Perform logical comparison of two operands and

set flag accordingly

SHIFT Perform logical shift (right or left) of the content

of a register

ROTATE Perform logical shift (right or left) with

wraparound of the content of a register