One,Two and Three byte Instructions

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One Byte Instructions needs only one Byte of memory for execution.
Here, in these instructions, general purpose registers are used as operands i.e. Source Register Rs and Destination Register Rd.
Example: MOV , LDAX, STAX, XCHG

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SBI

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Syntax: SBI 8bit  Where 8-bit is an immediate data operand.  Byte: 2byte Addressing Mode: Immediate   Addressing Working:  1.  2. A= A- 8bit -b 3.  4. Flag Example: SBI 10H where  [A]= 22H and [c flag]= 1 After execution of SBI   10H [A] = 11H  // A= A-8bit-b => 22-10-1 =11H Program: write an ALP for subtraction of 30H value from Registers A  Where A carries 44H and Cy flag carries borrow value 1. Store result at memory location 5000H. Label  Mnemonics  Comments Start:   SBI 30H        ;  a= a-8bit- cy...                                    ; A= 44- 30 -1 = 13h             STA 5000H   Stop: HLT Output: [5000H]= 13H      
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LXI Instruction

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Syntax: LXI Rhp,16-bit Where Rhp is Higher Order Register of the pair. (I.e. BC, DE, HL) Byte: 3byte Addressing Mode: Immediate Addressing Working: For execution of LXI Instruction, microprocessor will allocate first byte for opcode, second byte for lower order address/data and third byte for higher order address/data. Example: LXI H,2200H After execution of  LXI H,2200H [L] = 00H [H] = 22H
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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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