Writing a register with reserved bits-LPC1317 64P

[lpcware]

Content originally posted in LPCWare by aamir ali on Sat Feb 09 05:19:26 MST 2013
How to write a register with reserved bits.
Like I have DIR register & its P1.30 is reserved (just assumed)

Then should I always write zero to reserved bit, or I should
first mask the reserved bit & then write the register.

[lpcware]

Content originally posted in LPCWare by micrio on Sat Feb 09 07:03:52 MST 2013
By convention, and often explicitly stated, you should always write zero to
reserved bits.     If it is a bit banded register then you could use that feature
to avoid writing the bit but it is not necessary.

Pete.