Four months later, Atari released the 600 and 800 XL computers in hope of getting Atari Computer users back to buying their computers. This time the XL computers WERE compatable to the older 400 and 800 computers. But, Really they weren't exactly...why? When the newer XL's were released they came with a translator disk which was really the 400/800 OS! so once it was loaded into RAM, a 400/800 program could be run with ease as there was enough RAM for both OS and Program. as long as the program was coded with almost perfect skills it was compatable. The 600XL was now the entry level computer and as such was cheaper to buy.