Dumb question about Built-in Storage

I have read a few threads on this board about people saving files into this "Built-in Storage". I can see it under Settings/System/Memory/Storage Card. I have 21.24MB free space and I ventured to write a file to it and it worked!

This leads me to wonder what "Built-in Storage" is? Is it RAM or ROM? If it's ROM, why would I be able to write to it? Is it the same as my SD card? Would the information stored there be safer than in the Main Memory which is RAM?

I hope someone is kind enough to take the trouble to educate me:-) Thanks!

[JakeRich]

It is ROM. It's the "left over" portion of the ROM to which Dell has given us access. You can put things there and they will survive a hard reset. I put my backup files there so that if the Ax dies, I can rebuild it without having to connect to a PC somewhere.

ROM has a cycle life. I have heard that the Dell estimate is 100,000 writes. That's a lot of writes, so I wouldn't sweat it too much, but I would generally not want to put files in the ROM that change a lot. My average PPC "life" is about 2 years, let's say 750 days. That gives me about 133 writes per day. I suppose a busy person could get that many writes if you put something really volatile there, say the IE cache or Avantgo files.

thanks for the prompt reply. :P