The 400 was the computer to come out first. At the time, the Atari VCS was Atari's cash cow and with the millions of dollars it was just feeding Atari, there was almost nothing Atari couldn't get in to. SInce Atari had all of this money, what else to do but to spend it on research for some powerful computers! They decided to the the still Popular 6502 processor and eventually created Candy and Colleen, better known as the 400 and 800 computers. The 400 was to be an entry level computer with smaller childen in mind. The 400 had a membrane keyboard as so small children could not spill their food or drink into the keys 'gunking' them up. The 800 was more appealing to the Adults with its full stroke keyboard and greater expandability. Being almost Identical to the 400 internally the 800 could still beat the 400 with its more RAM and better cartridge ports.