Nanosecond One billionth of a second. Abbreviated to ns. Most DRAM rruns from 100ns to 60ns. Most cache RAM is under 20ns. This is where things like the time and date are stored when you turn off the power.
PRAM lives inside the clock chip.
Hold down the Command, Option, P and R keys as you restart your Mac. Keep these keys down until the Mac restarts twice. This will reset the PRAM back to the factor defaults. PROM Programmable Read Only Memory. RAM Random Access Memory.