Hello,
uC is AT89C52
clock is 11,0592 MHz
platform is Keil C
Im using Timer0 as 16 bit timer, with TH0 reload value of
0xA600.

Question : Is time between two interrupts equal 25 mS ?

Program :
void main {
TCON = 0x05;//IT1,IT0 = 1, (Irq0, Irq1 = H->L),
TMOD = 0x21;//Timer0 16 Bit Timer
TH0 = 0xA6;
TL0 = 0x00;
PT0 = ENABLE;
IE = 0x17; //Enable T0 Irq
TR0 = 1;

EA = ENABLE;
while (1) {
....Program
}//while
}//void main

void T0_Irq() interrupt TF0_VECTOR
{
EA = DISABLE;
TH0 = 0xA6; //TL0 avtomaticly conut up

...Program
EA = ENABLE;
}//End T0

Iztok