SBB

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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

     

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