A data acquisition unit accepts serial bit streams from a control device for a vending machine, and it records the data represented by those serial bit streams. The data in one of those serial bit streams will include the number of vends of each product corresponding to the various selection switches of the vending machine, and the data in the other of those serial bit streams will include the price data. The data acquisition unit will store the price data in a non-resettable location and also in a resettable location. A readout can be actuated to effect the displaying of the selection line number and of the corresponding settable and non-resettable price data.