Hello Sunny,

Think of the reset as a (non-maskable) interrupt which has 00h as its vector-address. Simply do as you do with other interrupts:

ORG 00h
LJMP  MAIN

Then define the starting address of MAIN:

ORG xxh
MAIN:
 ~ your code ~

I would advise agains starting MAIN at 23h, because that is the vector address for the serial interrupt. It is also a good idea to have a RETI instruction at each unused interrupt vector address. By the way, 03h is not the address for a timer interrupt, but for the External 0 interrupt.

Hope this helps.

Best regards,
Rob.