Yeah, something like this maybe:


PUSH PSW
CLR TR0 ;Stop timer
XCH A,TL0 ;Read overflow
ADD A,#LOW -TID0 ;Add new with comp for
XCH A,TL0 ;stopped cycles
XCH A,TH0 ;Also reload HI
ADDC A,#HIGH -TID0
XCH A,TH0
SETB TR0 ;Restart
POP PSW

Anders