SBB

Syntax: SBB R

Where R can be any of the general purpose registers (A,B,C,D,E,H andL)

Byte: 1byte

Addressing Mode: Register Addressing

Working: 

1. 

2. A= A- R-b

3. 

4. Flag

Example: SBB D

where [D] = 10H , [A]= 22H

and [c flag]= 1

After execution of SBB B

[A] = 11H 

[D] = 10H

// A= A-R-b => 22-10-1 =11H

Program: write an ALP for subtraction of values present in Registers A ,B and C. Where A carries 44H and B carries 30H and C carries 10H. Store result at memory location 5000H.

Label  Mnemonics  Comments

Start: SUB B ; a=a - b// 44-30= 14h

          SBB C ; a= a - c - cy... A= 14-10-0 = 4h

          STA 5000H 

 Stop: HLT

Output: [5000H]= 04H