Executive Summary of the
Non Volatile Memory Chips Inside Apple Computers.
Commonly known as "NVRAM" chips.

• Generally speaking, this type of ram is equivalent to the nvRAM the BIOS uses in a IBM-PC type computer to save the time and date.
  
  
• The "Open Firmware" chip in a Apple, and again generally speaking, is equivalent the the BIOS chip like the Phoenix or AMI chip used in a IBM-PC type computers.
  
  
• Understanding this type of memory is often confusing in Apple computers, especially in their laptops.
  
  
• Going to the Apple support website and others does not help, and will get you even more confused!!!

1. The "Parameter Random Access Memory" or pRAM:
   
   • Stores the information "Open Firmware" uses.
   • It is managed via the /usr/sbin/nvram terminal command.
   • The use of the nvram terminal command, is why it is often referred to as NVRAM incorrectly !
   
   
2. The Power Management Unit or PMU and the System Management Controller or SMC:
   - Both perform similar functions, but are called different names depending on what CPU you have.
   • The PMU, is used on the older PPC computers.
     - The PowerPC CPU chip is made by Motorola.
     
     
   • And the SMC, is used on the newer INTEL based computers.
     - The INTEL CPU chip is made by ....... guess who .....
   
   
3. And a THIRD type is often included, but is not RAM at all.
   (It's kinda sorta like a secret disk partition)
   
   • Is called rEFIt or EFI...

Not sure if you have a PPC or INTEL CPU chip ? Open up a terminal window and type,
/usr/sbin/system_profiler SPHardwareDataType | grep "Processor Name"

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