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Hi, I have a few things I need to clear about on memory.

Is RAM memory on today's computer all (Volatile) that means that when the computer is turned off all data in the memory is lost? Or is part of it "stay resident?" and if part of it is stay resident, how is it kept alive ? (The CMOS is form of memory ROM and is stay resident and kept alive with the metal oxide battery).

Finally if I had to change all the memory of my computer with new modules, will that cause any loss of settings or configurations (basing on the idea that RAM is partly "stay resident").

RAM has always been volatile... say you were doing work you forgot to save... the data is stored in RAM temporarily and lost when the machine powers off.

Adding or upgrading (e.g. PC100 to PC133) modules usually has no significant difference, just that your BIOS will automatically take effect of the new settings.
Ok so if RAM is lost when the computer is turned off, how does your computer remember all your preferences and settings? Are they recorded in your registry and is your registry stored on your hard disk or in memory?

the CMOS settings are saved on the motherboard in a type of memory that, by definition, could be called "RAM"... although, its not the same "RAM" or "Memory" as you are thinking of.

That CMOS storage area can be called CMOS RAM.

The CMOS settings could NOT be saved on the hard drive (including the registry) since the CMOS settings are what allows your computer to figure out how to use the hard drive to begin with... without having the CMOS settings loaded, your computer has no idea how to use the hard drive

There is a type of RAM was can retain information after losing power.. called SRAM ... but SRAM is very expensive and it usually used in memory caches.

The computer BIOS is stored in an EPROM (Erasable Programmable Read Only Memory). It functions, for all intents and purposes as Read-Only memory.. but can be reprogrammed with new information (aka "Flashing your BIOS")

I hope this helps
So to make it clear, what is the main difference between the CMOS and the BIOS?, is the BIOS the EPROM chip? or the BIOS the low level software? WHen you enter the BIOS during boot up, is that programme saved in the BIOS chip which is a form of EPROM?

I'm just a bit confused between the two :confused
think of it this way... the BIOS is the programming the manufacturer wrote... and is stored on the EPROM... if you went back to the computer 10 years later, the BIOS would still be intact... since the EPROM chip can store information for the physical life of the chip.. or until its overwritten.

the CMOS is your specific settings that you selected (hard drive type, memory type, memory speed, enable/disable certain system devices) from the BIOS setup program. Your responses are stored in CMOS RAM which requires a tiny amount of energy to keep the information intact.. without the battery on the motherboard, your answers (the customized settings in the BIOS) would vanish

So.. to sum it up... when you run the setup at boot time, the setup program is from the BIOS, while your answers are saved in the CMOS

hope that helps
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