Transaction system with independent transaction modules and associated executing code

摘要

A transaction system, e.g. a vending machine comprises a plurality of transaction units 4,6,8,10 each for performing a respective type of transaction, e.g. coin changer, banknote validator, card reader, vending mechanism. The units are interconnected via a serial link, and there is a common controller 16 which has respective protected memory areas (28,30,32,34 in fig.2) storing Java (RTM) code for controlling the respective units. High level operation of the transation units is performed by a Java Virtual Machine (26 in fig.2). A further code unit handles overall transaction control and authorisation. The controller has an Application Programmer Interface (API), consisting of Java bytecodes representing Java classes which can be used by the various transaction units.