Abstract: A control circuit for a vendor for vending a plurality of items comprising a microprocessor, an electrically alterable memory, a display circuit and an interrogation circuit. Values of parameters, typically prices, associated with the items to be vended are stored in the memory. The interrogation circuit can be activated to retrieve from memory the value of the parameter (e.g., price) associated with any given item. The parameter value is thereupon displayed by the display circuit. The display circuit displays the parameter value retrieved from memory independently of whether the microprocessor has another input equal in value to the value of that parameter. The parameter value stored in the memory for any given item can be altered by the microprocessor.