Nokia RH-9 Series Ccs Technical Documentation page 53

RH-9
CCS Technical Documentation System Module & UI
Figure 18: An XOR comparison of the data indicates more equal bits
Figure 19: An XOR comparison indicates more unequal bits
The Power Save function provides additional delay (10-15 ns) in random access, there-
fore it is only active in burst mode. Also, PS mode does not apply to the address, so the
address will always be presented in its true value. For burst access, it is possible to
remove the delay caused by the comparison logic by pipelining the power save function
and comparing the contents of the data in the burst with each other before putting it on
the bus. The PS function is disabled at initial power up and needs to be activated through
writing to the command register.
Block Locking
Block locking is used to prevent accidental writing to some sectors in the flash. AMD and
Intel will implement their block locking in the following ways.
Currently, all block locking is done with software and the hardware locking with the WP#
pin is not activated (in the hardware configuration software) and is therefore not used at
all.
Intel
The locking scheme offers two levels of protection. The first allows software-only control
of block locking (useful for frequently changed data blocks) while the second requires
Issue 1 11/02 ãNokia Corporation Page 53