10100000
Is the R/W bit. Leave it as "0" and PBP takes care of parsing it to a "1" if needed.

10100000
Are the A0 and A1 bits. If pins A0 and A1 are connected to the zero rail leave as zero. Mixing and matching on or the other or both gives the four combination's for up to four chips on the same bus.

10100000
Is the bit to set to read or write to the first or second block.