Packing & Unpacking of BCD numbers: 8085 programming

In this post, we will write programs in 8085 Assembly Language for Packing and unpacking of BCD numbers.

Packing of BCD numbers: 8085 programming

Problem statement:

Pack the two unpacked 4-bit single digit BCD numbers stored in memory locations C200H and C201H and store result in memory location C300H. Assume the least significant digit is stored in C200H.

Input Data:

Memory Address(H)	Data(H)
C200 C201	04 09

PROGRAM (8085 assembly code) for Packing of BCD numbers

Memory Address(H)	Machine Code(H)	Label	Mnemonics(Instruction)	Comments
C000 C001 C002	3A 01 C2		LDA C201H	Get the Most significant BCD digit
C003 C004 C005 C006	07 07 07 07		RLC RLC RLC RLC	Adjust the position of the second digit (09 is changed to 90)
C007 C008	E6 F0		ANI FOH	Make least significant BCD digit zero
C009	4F		MOV C, A	store the partial result
C00A C00B C00C	3A 00 C2		LDA C200H	Get the lower BCD digit
C00D	81		ADD C	Add lower BCD digit
C00E C00F C010	32 00 C3		STA C300H	Store the result
C011	76		HLT	Terminate program execution

BCD NO.: The numbers “0 to 9” are called BCD (Binary Coded Decimal) numbers.

Result

Memory Address(H)	Data(H)
C300	94

Unpacking of BCD numbers: 8085 programming

Problem statement:

Unpack the two digit BCD number in memory location C200H and store the two digits in memory locations C300H and C301H, such that memory location C300H will have lower BCD digit

Input Data:

Memory Address(H)	Data(H)
C200	58

PROGRAM (8085 assembly code) for Unpacking of BCD numbers

Memory Address(H)	Machine Code(H)	Label	Mnemonics(Instruction)	Comments
C000 C001 C002	3A 00 C2		LDA C200H	Get the 2 digit packed BCD number
C003 C004	E6 F0		ANI FOH	Mask lower nibble
C005 C006 C007 C008	0F 0F 0F 0F		RRC RRC RRC RRC	Adjust higher BCD digit as a lower digit
C009 C00A C00B	32 00 C3		STA C300H	Store the partial result
C00C C00D C00E	3A 00 C2		LDA C200H	Get the original BCD number
C00F C010	E6 0F		ANI OFH	Mask higher nibble
C011 C012 C013	32 01 C3		STA C301H	Store the result
C014	76		HLT	Terminate program execution

Result

Memory Address(H)	Data(H)
C300 C301	08 05