Thanks a lot for you guys' help!!
It turns out that if I select,
'CKSEL = 0010 Internal RC Oscillator'
instead of 'CKSEL=1111 External Crystal/Ceramic Resonator' in the fuse bit, I would be able to perform ISP. However, how come I cannot use the CKSEL=1111 option since I do have an external crystal at 2.45MHz on the STK500 with the proper oscel jumper and my Tiny12 is for 8MHz?
My second question is what are the steps to setup the micro-processor to use external crystal. Do I need to set the port direction by setting DDRB to 0 and PORTB to 1?
My last question is when I set the fuse bit to 'CKSEL = 0010 Internal RC Oscillator' and I assign OSCCAL to 0xFF in my code, it only give me a 1MHz clock. What do I need to do in order to have the maximum
2.5MHz?
Thanks again for your help, I greatly appreciate.
Regards, feilip