GeeksforGeeks App
Open App
Browser
Continue

# 8086 program to subtract two 8 bit BCD numbers

Problem – Write a program in 8086 microprocessor to find out the Subtraction of two 8-bit BCD numbers, where numbers are stored from starting memory address 2000 : 500 and store the result into memory address 2000 : 600 and carry (borrow) at 2000 : 601.

Example –

Algorithm –

1. Load data from offset 500 to register AL (first number)
2. Load data from offset 501 to register BL (second number)
3. Subtract these two numbers (contents of register AL and register BL)
4. Apply DAS instruction (decimal adjust)
5. Store the result (content of register AL) to offset 600
6. Set register AL to 00
7. Add contents of register AL to itself with carry (borrow)
8. Store the result (content of register AL) to offset 601
9. Stop

Program –

400MOV AL, [500]AL<-[500]
404MOV BL, [501]BL<-[501]
408SUB AL, BLAL<-AL-BL
40BMOV [600], ALAL->[600]
40FMOV AL, 00AL<-00
413MOV [601], ALAL->[601]
417HLTEND

Explanation –

1. MOV AL, [500] load data from offset 500 to register AL.
2. MOV BL, [501] load data from offset 501 to register BL.
3. SUB AL, BL subtract contents of registers AL AND BL.