Hi Vaclav and Peter, thank you for your suggestion. Actually I have considered of using a divided by 4 chip to get the 50Hz signal. However, a frequency divider will always give me a 50% duty cycle which is something I don't like. In fact, the RC servo operates at about 5 to 12% duty cycle.

This is my code written in C. However, it doesn't works quite right.

*********************************************

main()
{
main2()
}

org 0x8100
main2()
{
TMOD = 0x11

TL0 = 58
TH0 = 143
ET0 = 1
EA = 1

TL1 = 190
TH1 = 10
ET1 = 1
EA = 1

TR0 = 1
TR1 = 1

P1.0 = 0
Repeat
goto Repeat
}

// Timer 0 overflow interrupt routine
org 0x800B
timint0vector()
{
TR0 = 0
TMOD = 0x11
TL0 = 58
TH0 = 143
ET0 = 1

TL1 = 190
TH1 = 10
ET1 = 1
EA = 1
TR0 = 1
TR1 = 1

P1.0 = 1
reti()
}

// Timer 1 overflow interrupt routine
org 0x801B
timint1vector()
{
P1.0 = 0
TR1 = 0
reti()
}

I don't know what's wrong :(
Hey guys, thanks for you help again.

Michael