It should be noted that the first commonly-used "main store" in computers was "core" -- tiny toroids of ferrite material arranged in an array, with wire running through them in 3 directions.

To write a 1 you'd send equal strength pulses through the corresponding X and Y wires, to "flip" the core. (To write a zero you wouldn't.) You'd have to erase the location before writing.

To read you'd try to write a 1 and see if a corresponding pulse was generated on the "sense" wire -- if so the location used to be a zero. Then you'd of course have to write the data back, since you'd just erased it.

(This is a slightly simplified description, of course.)

But the stuff was non-volatile. You could shut down the computer, start it up a week later, and the data would still be there. And it was most definitely "RAM".

(Before "core" most computers operated directly of a magnetic "drum", with only a few registers of CPU memory, and a few used stuff like storage CRTs.)

So, the answer as to why RAM (in it's current, most common form) is volatile is simply that that form is cheap and fast. (Intel, interestingly enough, was the early leader in developing semiconductor RAM, and only got into the CPU business to generate a market for their RAM.)

It should be noted that the first commonly-used "main store" in computers was "core" -- tiny toroids of ferrite material arranged in an array, with wire running through them in 3 directions.

To write a 1 you'd send equal strength pulses through the corresponding X and Y wires, to "flip" the core. (To write a zero you wouldn't.) You'd have to erase the location before writing.

To read you'd try to write a 1 and see if a corresponding pulse was generated on the "sense" wire -- if so the location used to be a zero. Then you'd of course have to write the data back, since you'd just erased it.

(This is a slightly simplified description, of course.)

But the stuff was non-volatile. You could shut down the computer, start it up a week later, and the data would still be there. And it was most definitely "RAM".

(Before "core" most computers operated directly off a magnetic "drum", with only a few registers of CPU memory, and a few used stuff like storage CRTs.)

So, the answer as to why RAM (in it's current, most common form) is volatile is simply that that form is cheap and fast. (Intel, interestingly enough, was the early leader in developing semiconductor RAM, and only got into the CPU business to generate a market for their RAM.)