DEAR TO ALL, I AM DEALING WITH C8051F120 MICROCONTROLLER.UTILIZING 16 X 16 MAC ENGINE OPERATION.I AM DOING ASSEMBLY LANGUAGE PROGRAMMING USING THIS MICROCONTROLLER FOR MULTIPLICATION. IS IT POSSIBLE TO MULTIPLY TWO UNSIGNED 16 BIT INPUTS? IF YES, THEN HOW ?
"That is a question that's usually treated in large books."
It is a common fallacy that the mere act of writing in assembler will inherently give you fast, tight code.
This is simply not true: it takes a great deal of skill and experience to write fast, tight code in any language! Sure, assembler gives you more opportunities - but you need to know how to use them!
If you need to ask basic questions like how to use ACALL and LCALL, you're probably not quite ready to be turning out super-optimised code...
You might even find that the compiler can do a better job - especially with optimisations enabled (but then that gives you the issues with debugging - which comes back to skill & experience)