A data processing system according to the invention comprises a system controller and a plurality of ECRs connected to the system controller. Each ECR has a keyboard for inputting sales data per slip number (kind). The ECR obtains the subtotal per kind of the input sales data. The subtotal is transmitted...http://www.google.com/patents/US5018066?utm_source=gb-gplus-sharePatent US5018066 - System for processing sales data on slips used in restaurants
