Program to convert ASCII to HEX in 8085 Microprocessor

Here we will see one 8085 Microprocessor program. This program will convert ASCII to HEX values.

Problem Statement −

Write an 8085 Assembly language program to convert ASCII to Hexadecimal character values.

Discussion −

We know that the ASCII of number 00H is 30H (48D), and ASCII of 09H is 39H (57D). So all other numbers are in the range 30H to 39H. The ASCII value of 0AH is 41H (65D) and ASCII of 0FH is 46H (70D), so all other alphabets (B, C, D, E, F) are in the range 41H to 46H.

Here the logic is simple. We are checking whether the ASCII value is less than 58H (ASCII of 9 + 1) When the number is less 58, then it is numeric value. So we simply subtract 30H from the ASCII value, and when it is greater than 58H, then it is alphabetical value. So for that we are subtracting 37H.

Input

first input

Address	Data
…	…
8000	41
…	…

second input

Address	Data
…	…
8000	35
…	…

third input

Address	Data
…	…
8000	46
…	…

Flow Diagram

Program

Address	HEX Codes	Labels	Mnemonics	Comments
F000	21, 00, 80		LXI H, 8000H	Load address of the number
F003	7E		MOV A,M	Load ASCII data to Acc from memory
F004	FE, 58		CPI 58H	Compare with ASCII(9) + 1
F006	D2, 0E, F0		JNC NUM	The input is numeric
F009	D6, 37		SUI 37H	Subtract offset to get Alphabetic character
F00B	C3, 10, F0		JMP STORE	Store the result
F00E	D6, 30	NUM	SUI 30H	Subtract 30 to get numeric value
F010	23	STORE	INX H	Point to next location
F011	77		MOV M,A	Store Acc content to memory
F012	76		HLT	Terminate the program