Richard,

There is another code:

MVI D,000H ;New value Y in E
DAD H ;2*X
XCHG
DAD D ;HL=2*X+Y, DE=2*X
XCHG
DAD H ;HL=4*X
DAD H ;HL=8*X
DAD D ;HL=10*X+Y

It works on 20% faster and use HL and DE only.

Regards,

George