WriteParam
WriteParam Write Parameter RAM data to non-volatile RAM #include <OSUtils.h> Operating System Utilities
WriteParam copies the 20 bytes of data starting at SysParam into the non-volatile clock-chip memory. This can be used after modifying one or
more system parameters (such as the default speaker volume) to make those
parameters "permanent".
prWrErr (-87) Couldn't verify the write
system parameters in memory, then use WriteParam to make those values "permanent".
It is possible to alter the contents of the Parameter RAM so much that the
Mac won't start next time you boot. In that case, you can reset the
Parameter RAM by pulling the battery for about 5 minutes.
To zap the PRAM, hold down the cmd, shift and option keys and select the
Control Panel from the Apple menu.