Thanks Peter I will try that code
Charles i am using metalink asm51 assembler and it does not give error any way that part of code is of no use as it is simple delay.
i have now made program using polling posted at
http://www.8052.com/users/gop8051/gopal.asm
but again it is giving wrong result.
the result as i get on hyperterminal is given below the code
which gives igh period and low period of wave form in hex code

I checked with an oscilloscope.This is result i got
Period of wave 300us
high period 130 us
low period 170us
Duty cycle=0.32-0.0047*temp
using this value i cal temp and was correct at 25 degree celcius

so i am pretty sure i am doing some mistake in intialisation of timers.Pls can somebody point out the mistake