You have to convert the number 65486 into hecadecimal. In other words convert from base 10 to base 16. I use a calculator that has hex mode to do this conversion. (for example Hewlett Packard 20S Scientific. Casio also has come models which do this).

The conversion 65486 == FFCEh.

The high byte if this is FFh and the low byte is CEh.

So to program this value into the timer 0 register is like:

MOV TH0,#FFh
MOV TL0,#CEh

Note that the "calc.exe" that comes with Windows has the capability to do decimal to hex conversion as well.

Michael Karas