Data Transfer and Manipulation | Computer Architecture

Data Transfer and Manipulation in Computer Architecture – Most of the computer systems have a common set of basic set of operations and corresponding instructions. However, the opcode for these instructions may differ for the same operation in different computer systems.

The general instruction set of a computer has already been discussed in the given article. – Instructions Types in Computer Architecture. So, in brief, again we can classify instruction set in three categories.

1. Data Transfer Instructions
2. Data Manipulation Instructions
3. Program Control Instructions

Data Transfer Instructions

Data transfer instructions move the data from one location (source) to another location (destination) without changing the contents of the source location. The most common transfers are between memory and processor registers, between processor registers and input/output, and between the processor registers themselves. The table shows the most common data transfer instructions with their respective mnemonic and function.

Name	Mnemonic	Function
Move	MOV	Load (copy) the data from memory to processor registers (mostly the accumulator)
Store	ST	Copy the data from the source location to the destination location.
Load	LD	Load (copy) the data from memory to processor registers (mostly the accumulator)
Input	IN	Write the data from the processor registers to the top of the stack.
Output	OUT	Transfer data from processor registers (mostly the accumulator) to the output terminal.
Push	PUSH	Write the data from the processor registers to the top of the stack.
Pop	POP	Read the data from the top of the stack to the processor registers.
Exchange	XCH	Write the data from the processor registers to the top of the stack.

Data Manipulation Instructions

The data manipulation capability of a computer system shows its computational capability. The data manipulation instructions can further be classified into three categories:

1. Arithmetic
2. Logical
3. Shift Instructions

There are four basic arithmetic operations: addition, subtraction, multiplication, and division. However, some small computers have only addition and subtraction capabilities. Multiplication and division are performed through subroutines. The table below shows some of the arithmetic data manipulation instructions.

Arithmetic Name	Arithmetic Mnemonic	Logical Name	Logical Mnemonic	Shift Name	Shift Mnemonic
Add	ADD	AND	AND	Logical shift right	SHR
Subtract	SUB	OR	OR	Logical shift left	SHL
Increment	INC	Exclusive OR	XOR	Arithmetic shift right	SHRA
Decrement	DEC	Complement	COM	Arithmetic shift left	SHLA
Multiply	MUL	Clear	CLR	Rotate right	ROR
Divide	DIV			Rotate left	ROL

Logical instructions perform binary operations on strings of bits stored in processor registers.

These instructions are useful for manipulating individual bits or a group of bits. The common logical operations are AND, OR, XOR, and NOT. Instructions for these operations are given in the above table.

In data manipulation instructions, there are four types of shift operations: (i) logical, (ii) arithmetical, (iii) rotate left, and (iv) rotate right. The related instructions are shown in the above table.

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