PortB = PortBnewdata & $FE ' Will this only change the values on bits 1 to 7
This will leave all <7:1> as is BUT it will clear bit0

Assuming PortBnedata=$FF - AND with $FE give... $FE

If you want set set a bit, you'll need to use -OR-

Portb = PortBnewdata | $1

You can use windows calc in scientific mode if you want. From the link you have posted, looked at the one i've posted about boolean operations/theory.