CONCEPT OF INSTRUCTION
The CPU is a semiconductor integrated circuit chip consisting of a large number of
transistors. In personal computers, the CPU is also referred by the term Microprocessor.
Every CPU is capable of performing certain instructions (known as machine instruction).
Modern CPUs have the logic built in to perform 400-550 machine instructions. The
machine instructions that a CPU can execute demonstrates its capability. Every processor
is capable of performing certain operations. An instruction refers to an operation that can
be performed by the processor directly. The entire set of instructions that can be executed
by the processor directly, through the logic in hardware, form the instruction set of the
processor. An instruction tells the processor what task is to be performed and what
microoperations need to be completed to perform the task. Every instruction execution
requires
execution of a set of arithmetic and logical operations (micro-operations). The size and
format of the instruction varies with different processors.
Every instruction is comprised of two parts: opcode and operands. The opcode specifies
the operation to be performed and the operands provide the data on which the operation is
to be performed. To understand the concept of instruction more clearly let us assume a
simple hypothetical computer which the capability to perform eight different operations.
Every operation is specified by a unique opcode as given in Table 2.2.
Table 2.2 : Unique OPcode
Operation Opcode
Addition 000
Subtraction 001
Multiplication 010
Division 011
Modulus 100
Complement 101
Bitwise AND 110
The CPU is a semiconductor integrated circuit chip consisting of a large number of
transistors. In personal computers, the CPU is also referred by the term Microprocessor.
Every CPU is capable of performing certain instructions (known as machine instruction).
Modern CPUs have the logic built in to perform 400-550 machine instructions. The
machine instructions that a CPU can execute demonstrates its capability. Every processor
is capable of performing certain operations. An instruction refers to an operation that can
be performed by the processor directly. The entire set of instructions that can be executed
by the processor directly, through the logic in hardware, form the instruction set of the
processor. An instruction tells the processor what task is to be performed and what
microoperations need to be completed to perform the task. Every instruction execution
requires
execution of a set of arithmetic and logical operations (micro-operations). The size and
format of the instruction varies with different processors.
Every instruction is comprised of two parts: opcode and operands. The opcode specifies
the operation to be performed and the operands provide the data on which the operation is
to be performed. To understand the concept of instruction more clearly let us assume a
simple hypothetical computer which the capability to perform eight different operations.
Every operation is specified by a unique opcode as given in Table 2.2.
Table 2.2 : Unique OPcode
Operation Opcode
Addition 000
Subtraction 001
Multiplication 010
Division 011
Modulus 100
Complement 101
Bitwise AND 110
