bootable ram drive

I remember running accross a set of schematics for a bootable "ram drive". It was an old set of schematics and was only a 1 meg or so ram drive. I am looking for a way to tell the computer (bios) that there is a harddrive hooked up. and the specs of the drive. the device will plug into the IDE cable as a regular harddrive would.

If anyone had any information that might help. thank you.