MUL instruction in 8086 | Instruction set of 8086 microprocessor
MUL instruction in 8086
The IMUL instruction allows the multiplication of two signed operands. When the operand is a byte, it is multiplied with AL register and when it is a word, it is multiplied with AX register. The operation of MUL and IMUL instructions are same.
The mul instruction has 2 operands: one is specified and the other one is implicit. When you write mul cx it means something like: ax = ax * cx . Actually it means dx:ax = ax * cx - the high half of the full 32-bit product is always written to dx . dx will be zero for small products where the result "fits" in ax