The Atari 820 printer provided Atari 400/800 users with a quick and simple printer.   No drivers or special interfaces were needed.   The Atari 820 printer plugged directly onto the Atari SIO bus and allowed users the ability to make 40 column printouts which were good for tracking finances, printing out program listings and other files.   The printer made an interesting sound which could only be described as a washing machine.