Abstract: A transaction system comprises a plurality of transaction units each for performing a respective type of transaction. The units are interconnected via a serial link, and there is a common controller which has respective protected memory areas storing Java code for controlling the respective units.

Abstract: An electrical discharge produces an acoustic impulse, and a reflection of the impulse from the upper coin in a coin stack is sensed so that the level of the coin stack can be determined from the time taken for the reflection to be received. Alternatively, or additionally, the acoustic impulse can be used to detect coin jams, the presence and/or width of a coin store, the state of a coin routing gate or the quantity of a vendible product.

Abstract: An electrical discharge produces an acoustic impulse, and a reflection of the impulse from the upper coin in a coin stack is sensed so that the level of the coin stack can be determined from the time taken for the reflection to be received. Alternatively, or additionally, the acoustic impulse can be used to detect coin jams, the presence and/or width of a coin store, the state of a coin routing gate or the quantity of a vendible product.

Abstract: A transaction system comprises a LAN incorporating a plurality of transaction units and a server. The server can cause the transaction units to perform operations, such as revaluations, on respective, predetermined smart cards inserted into the transaction units in response to instructions received externally, for example via the internet. The unit server stores a database, accessible via the internet, including the credit values stored by the data-carrying devices. The information is reconciled each time a device is inserted in the transaction unit. Revaluation can take place in a progressive, timed manner.

Abstract: A method of testing coins comprising at least taking two measurements of an unknown coin: and accepting said unknown coin as corresponding to a first coin type if the point defined by the measurements lies, in the space defined by the axes of the measurements, on a first side of a discriminant surface at which the Mahalanobis distances of the centers of the distribution of said first coin type and a second coin type are in a predetermined relationship, characterized in that said relationship corresponds (at least approximately) to equality of the sums of the respective Mahalanobis distances with respective predetermined constants at least one of which is non-zero.