I need to multiply two 4 byte numbers. I can store those values in the x,y,z registers but then how do I multiply them since I can only multiply 8x8 bits at a time? I know how to allocate memory in dseg but arithmetic functions can't be performed there.
 The devices I'm using for simulation are 169p and the 2560. Mul may be used. 

I have tried using the x,y,z registers but I can't figure how to take care of the carries and such. I know that they can be found in registers 0,1 and so fourth. I tried to allot memory locations large enough to store the numbers for arithmetic but I would have to move them to registers for operations anyway.