Dear Vijayganesh
Excuse me if my reply ia late, unfortunately i am very busy nowadays.
But I read your code exactly.I have 2 questions
and offer 3 suggestions.

question:
1).
what is relation between external and timer interrupts.

2).
Have i understand correctly your problem?
Do you want start fetching look up table when coming external interrupt
and repeat it periodically with masking interrupt.
If my guess is ok why you don't polling a pin until it goes high or low?
and if you want every second fetching will occur
why when r1=0,total execution time before reaching to [sjmp repeat]
is 6.0451936 Second.It is a very large moment that damage to your
1 hertz's desired duration!


suggestion: {If i was understand your aim.}

1).
because of pulse generation is starting from external interrupt
You can provide the first pulse manually and then resume every 1 second
with desired delay loop depending your code,for example 19 ms

2).
Why you set and reset r1 as a flag? the interrupt is the best flag
in every program.just you must optimize your achievement.


ORG 0X0000
LJMP MAIN

ORG 0X0013
ISR_IE1:
SETB TR1
ORG 0X001B
ISR_TR1:
...
...
...
...
RETI


MAIN:
SJMP MAIN

so ISR_IE1 & ISR_TR1 is same executing


3).
it is not necessary clearnig ie.2 in edge triggering mode or
external interrupt routine.


If new things is existed please notify us for more help.
Regards
Mehdi