Thanks again Melanie,
Hmmm, I think I almost understand what's going on with that code. I must actually be learning something.

I ended up with this, from the code you supplied and it works excellent.

Code:
increminute: 

        rtcmathtemp =(rtcmin>>4)*10+(rtcmin & $0F)  'convert BCD minutes into Decimal minutes
        
        rtcmathtemp=rtcmathtemp+1   'increment by 1
        If rtcmathtemp>59 then      'If minutes exceeds 59
        rtcmathtemp=0               'reset to 0
        endif
  
        rtcmin=((rtcmathtemp DIG 1)<<4)+rtcmathtemp DIG 0 'convert Decimal back to BCD

        gosub settime
       
        return