Process to Design a Flowchart of Program

Flowchart Design Process – The development steps of a program can be shown with a pictorial format, called a flow chart. Hence, the flow chart is a graphical tool that allows programmers to represent various actions that are to be performed. The role of a flow chart to solve any problem through software is the same as that of a block diagram in any hardware.

The graphical representation is very useful for a better understanding of the programming logic. In the flow chart, general language instructions are converted into symbolic representation. The advantage of symbolic representation is that a common person can understand the meaning of the instruction. Graphic symbols used in a flow chart are shown in the figure below.

Let’s take an example program to write an assembly language program to add two hexadecimal numbers, 13H and 26H, and display the result at port address 02H.

Solution: Development of the program involves the following steps.

1. Problem statement
2. Problem Algorithm
3. Implementation of Instructions
4. Debugging
5. Manual Assembling
6. Store the program
7. Execute the program

Problem statement – Instruct the processor to add 13H and 26H and display the sum at the port address 02H.

Problem Analysis – Analysis of the problem is done with the help of an algorithm and a flow chart.

Algorithm:

• Step 1: Store the numbers in two different registers, where one must be the accumulator.
• Step 2: Add the second register contents to the contents of the accumulator.
• Step 3: Display the result at the port address 02H.
• Step 4: Stop the execution.

Flowchart of the program – A flowchart is the pictorial representation of the sequence of steps discussed in an algorithm. The flowchart for the given problem is shown in the figure below.

Implementation of Instructions – The next step is to convert the flowchart into an assembly language program. Assembly language translation is shown as follows:

Algorithm	Flow Chart	Instruction	Comments
Step 1	Block 1	MVI A, 13H MVI B, 26H	Load Accumulator with 13H Load register B with 26H
Step 2	Block 2	ADD B	Add the contents of register B to the contents of accumulator
Step 3	Block 3	OUT 02H	Display the sum (contents of the accumulator) at port address 02H
Step 4	Block 4	HLT	Stop the execution

Debugging – Now the assembly language program is ready and can be tested for proper functioning.

Manual Assembling – The assembly language program is now to be converted into its equivalent machine language program.

Instruction Opcode	Instruction Operand	Hex Code
MVI	A, 13H	3E 13
MVI	B, 26H	06 08
ADD	B	80
OUT	02H	D3 02
HLT		76

Store the Program – The next step is to store the program in the predefined memory space. Let the user memory start from 7000H.

Instruction Opcode	Instruction Operand	Hex Code	Address
MVI	A, 13H	3E 13	7000H 7001H
MVI	B, 26H	06 26	7002H 7003H
ADD	B	80	7004H
OUT	02H	D3 02	7005H 7006H
HLT		76	7007H

Execute the Program – Now execute the program written in memory space from 7000H to 7007H. To execute the given program, the starting address 7000H has to be provided to the processor.