helo sir i have wrote asm code below. my 89c52 works on 12.0Mhz crystal.
/////////////////hardware points/////////////////////////
1) BUSY of ICL7135 connected to INTO of 89c52
2) CLOCK of ICL7135 connected to timer-0 pin of 89c52
////////////////////////////////////////////////////////

MOV TMOD, #0Dh ;timer-0 in 16bit counter mode and gated with INT0
MOV TH0, highbyte(-10,001d) ; load value with -10001 d
MOV TL0, lowbyte(-10,001d)
SETB TR0 ; start timer-0
JB INT0, $
MOV R0,TL0
MOV R1,THO