Hi George,

Yes, it is possible to change the reload register while the counter is running. If you use, for example, C/T 0, TL0 will hold the actual counter value and TH0 holds the reload value. When TL0 overflows (i.e. from 'FF' -> '00' ) the value of TH0 is copied into TL0 and TF0 is set (which will generate an interrupt, if enabled).

Hope this answers your question. Regards,
Rob Klein