HeatkitHeathkit / Zenith ET-3400 microcomputer learning system, very popular object in 1976 designed to teach the principles of programming and computers in universities in the 70s. Used to educate students in the knowledge of new components, hardware and software inside the computer through assembler and programming.It was delivered assembled or in kit form. It also featured a prototype area and could be used for the design and development of special interface circuits, such as a common 6820 parallel interface or 6850 asynchronous chips.Several ROM software were available. These include an assembler and a small BASIC.