hi Harsha;
May be you are right.I was just looking for a way to do it without using usual ANL.
Also my code should work independent of byte positions.NO DATA/IDATA problem due to R0 use.

BTW i had typed last line wrong.this is correct one.

upper_nibble equ xy
lower_nibble equ upper_nibble+1

nibble_join:

mov r0,#upper_nibble
mov a,@r0
swap a
inc r0
xchd a,@r0
ret

Pranav