What is the format of the MUL instruction

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The MUL(unsigned multiply) instruction has three formats: The first is to multiply an 8-bit operand by al. The second is to multiply a 16-bit operand by ax; the third is to multiply a 32-bit operand by eax

Multiplier and multiplicand must be the same size, and the size of the product must be twice the multiplier/multiplicand size. All three formats accept both register and memory operands. However, immediate operands are not accepted (note this).

For example:

If you want to multiply the value in the al register by 2, you need to store the immediate number 2 in a register and multiply it by mul, or place the immediate number in a memory address and multiply it by a memory location.

Examples:

mov bl, 2

mul bl ; Multiply the value in bl register by the value in al register at this point

The only operand in an instruction is a multiplier.

That is, when our multiplier is 8 bits, multiply by al, if our multiplier is 16 bits multiply by ax, if our multiplier is 32 bits multiply by eax register.

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