Looking at page 8 of this manual. (Table 7)
It shows the GDRAM Display and the X address is 0x00 to 0xFF (0 to 15) and each column consisting of two bytes or 16 bits.

If this is so then the display will be 256 x 64 and not 128 x 64 as stated.
Can you please clarify

Thanks in advance

Secondly writing data to GDRAM it states that the address counter is automatically incremented (or decremented) after the second byte of data is recieved. is this the X address or the Y address? or does it increase X up to 0xFF then increment the Y address while zeroing the X address?