Abstract: A controller for a multi-item vendor includes a memory, a set of manually operable selectors, an alphanumeric display, and a logic circuit. Information associated with the vending of items is electronically stored in the memory by categories such as price, throw, sales and diagnostic tests and each category is subdivided into units such as price for each item or a particular diagnostic test. Each category of information has its own selector. The logic circuit causes the display to display an identifying multi-character alphanumeric designation of a unit of information for each actuation of the corresponding selector and a numeric value, if any, of that unit. All units of a given category may be displayed by a sufficient number of actuations of the appropriate selector. A data security key permits a supervisor to prevent others from gaining access to certain categories of information, the locked categories being selectable and changeable by the supervisor by using the key.