Arithmetic and logic part A

To do Addition operation use instruction?

• ADD

• SUBB

• MUL

• DIV

After an ADD operation, the result will be stored in the destination operand.

Which operand serves as the destination?

• DPTR

• ADD

• A

• B

When adding two 16-bit data operands, the propagation of a carry from lower byte to higher byte is concerned.

How to perform addition of 16-bit?

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BCD is Binary Coded Decimal.

which answer most related to unpacked and packed BCD?

• BCD numbers are from 0 to F and a single byte has two BCD number in it.

• BCD numbers are from 0 to 9 and a single byte has two BCD number in it.

• Only the lower 4 bits of the number represent the BCD and a single byte has two BCD number in it.

• The lower 4 bits of the number represent the two BCD number. and a single byte has only a BCD number in it.

How to solve the problem of BCD number greater than 9

• add F to the lower digit.

• add 6 to the lower nibble.

• add F to the upper nibble.

• add 6 to the upper digit.

The “DA” instruction works only on A; while the source can be an operand of any addressing mode, the destination must be in register A in order for DA to work.

• TRUE

• FALSE

Which perfect explanation about DA instruction

• DA instruction will solve any problem associated with BCD.

• DA instruction will solve problem associated with BCD addition.

• DA instruction will add 6 to the lower nibble.

• DA instruction will add 6 to the lower nibble or higher nibble.

8051 has both SUB and SUBB (subtract with borrow) instruction

• TRUE

• FALSE

8051 used ADDER Circuit. to perform subtraction to reduce the number of transistor and simplify the operation.

How it is possible?

• does "CLR C" which clear the carry flag.

• does 2nd complement.

• if CY=0 (positive number) does 2nd compliment else no need.

• if CY=1 (negative number) does 2nd compliment then invert the result, else no need.

Both the MUL and DIV instructions utilize both the A and B registers, and the result is stored in these registers.

• TRUE

• FALSE