Hello,
OPTION.5 = 1 simply sets bit 5 in the option register but like I said in my previous post PBC doesn't support direct register access like that so you'll have to use POKE to write the registers and PEEK to read them. Look at the memory map of the device you're working with. You'll find at which adresses the various registers are. On the 16F628 the OPTION register is at location 80h for example.

Look in the PBC manual on how to use POKE and PEEK.

Why did I want to set bit5 in the option register? That's because it is the bit that select if TMR0 is a timer or counter and I found that information in the section of datasheet dedicated to TMR0.

/Henrik.