GB2348728A - Method of transferring data with redundancy - Google Patents

Abstract

A method of transferring data between a plurality of machines using a plurality of portable data storage elements individually insertable into the machines comprises dividing the data into sections and writing a section of data to each of a plurality of the data storage elements so that the data is carried in a redundant manner. Preferably different overlapping sections of data are written to different storage elements, e.g payment cards which also store credit data, and the sections of data are reassembled once they have all been received. In a preferred embodiment audit data is written to the cards when they are presented to a vending machine in which the cards are used to make purchases and the audit data is read from the cards, and then receipt data is written to the cards, by a machine which increases the amount of credit on the cards. The data transferred may alternatively relate to the configuration of the vending machine. A system for performing the method is also claimed. Other methods, systems and machines for manipulating and transferring data redundantly, in sections, or in addition to credit information on payment cards, are additionally claimed.

Description

Method and Apparatus for Collecting and Transferring Data The present invention relates to the collection and transfer of data, especially to the collection and transfer of data relating to machines for vending products or services, such as beverage dispensers, food dispensers, payphones and gaming machines. It is also applicable to other machines such as currency dispensers and machines for accepting payment such as a terminal in a shop.

For convenience, all such machines are referred to in the following as vending machines. Furthermore, the invention is more widely applicable, for example, to machines which use cards or other elements for operation or for identification of the carrier of the card or element.

In a preferred embodiment, the invention relates to vending machines which can accept payment from a card. It has been proposed that vending machines should accept payment by means of"smart cards", that is, payment cards which are generally credit-card shaped and sized, contain a memory and usually a microprocessor, and are machine-readable. It has also been proposed that certain types of such cards should store a credit value, which can be replenished in exchange for the owner making a payment, and which is diminished in accordance with the value of a product or service received by the owner. The term"card"will be used in the following, but that term is intended to cover memory-containing tokens which need not be credit-card shaped and sized.

It is known to collect data in a vending machine relating to the operation of the machine. More specifically, it is known to store audit data, relating to transactions performed by a machine, in the machine. The audit data is then collected from the machine, by various different means, for analysis at a site remote from the machine. EP 0 018 718 A, the contents of which are incorporated herein by reference, describes a system where a device including a removable module containing a non-volatile memory is fitted to a vending machine. Data concerning transactions which have been carried out by the vending machine is transferred into the module's memory. The module is then removed and fitted to a machine which can read out the contents of the module's memory. GB 2 129 173 A, the contents of which are incorporated herein by reference, describes a similar system. GB 2 176 639 A, the contents of which are incorporated herein by reference, describes a system where data from a plurality of gaming machines is transferred to a central computer via a communications link such as a public telephone network. It is also known to transfer audit data using an infra red or optical link between a vending machine and a portable data storage module.

A disadvantage of the known systems described above is that they either require a serviceman to visit a machine in person, which is relatively timeconsuming, or they require a set-up which is relatively complicated and expensive.

The present invention provides a method and apparatus for dividing data into sections and writing a section of data to each of a plurality of portable data storage elements individually insertable into a machine to carry data to and/or from said machine with redundancy. Further aspects of the invention are set out in the appended claims.

The invention can provide a system similar to a network for transferring data, without the cost of hardware or installation. In an application to vending machines for collecting audit data, it is not necessary to send a serviceman to visit each vending machine individually, or to invest in audit devices for each serviceman, which may result in a reduction in expenses. Also, the cost of the scheme after development is low. In a system using payment cards for transactions, the amount of data for transfer is related to the number of cards available for transferring the data, because the more transactions there are, the more cards there are available to carry the resulting data.

Embodiments of the invention will be described below with reference to the accompanying drawings, of which: Fig. 1 is a schematic drawing of a vending machine system according to the first embodiment; Fig. 2 is a schematic drawing of a vending machine; Fig. 3 is a schematic drawing of a vending machine system according to a fourth embodiment; and Figs. 4 to 7 are schematic drawings showing steps of a method according to the fourth embodiment.

Fig. 1 is a schematic illustration of a vending machine system according to the first embodiment of the invention. The vending machine operates using payment cards including an electronic cash feature. In other words, the cards can store a credit value, which can be replenished in exchange for the owner of the card making a payment and which is diminished in accordance with the value of a product or service received by the owner. The cards also include a data carrier feature, which will be described in more detail below. An example of a card which can support an electronic cash feature and a data carrier feature is a multi-application smart card such as a card with MULTOS, which is a multi-application operating system for smart cards. The vending machine system has n vending machines 2a to 2n, and two revaluation terminals 10,12, for increasing the credit value of the payment cards in exchange for cash. The revaluation terminals 10,12 are connected to a system manager 14, in the form of a central computer, by a network.

Each of the n vending machines will accept payment from cards with electronic cash which has been credited at one of the two specified revaluation terminals 10,12, but not from any cards with electronic cash which has been credited at any other revaluation terminals. Thus, the n vending machines, the revaluation terminals and the corresponding payment cards together define a self-contained system, known as a closed system, where each component of the system is usable with the other components of the system but not with the components of another such system. Such a system may typically be found, for example, in the premises of a company or in a hotel.

Referring to Fig. 2, which represents each of the vending machines 2a...

2n, each vending machine has a product vending section 16, a card reader 18 for reading from and writing to a card inserted into the vending machine, a control unit 20 and an input/output unit 22 comprising a display and a keypad.

The control unit of the vending machine includes a memory 24 for storing information about the operation of the vending machine. More specifically, the memory stores audit data, including transaction data containing information about each transaction carried out by the machine, and other data such as price information for each product available in the machine. The audit data can also include information such as the amount of credit accumulated to date, the total number of products sold, the number of products of each type sold, the number of failed transactions, and details of any identified faults in the machine. Transaction data includes, for example, the item selected for each transaction, the cost of the selected item, the type of payment and the identification code of the customer as indicated on the payment card.

The audit data are particularly useful to the operator of the vending machine, for example, for monitoring the day-to-day use and operation of the machine.

As described in more detail below, the system collects audit data including transaction data from the vending machines and supplies it to the system manager, using the data carrier feature of the payment cards which are presented to the vending machines and to the revaluation terminals.

To credit a payment card, it is inserted into a revaluation terminal, where the value of cash also inserted into the terminal is credited to the card.

When the customer wishes to use the card in a vending machine, the card, shown at 26 in Fig. 2, is inserted into the card reader 18. The card reader 18 then reads the credit value from the card 26 and the control unit 20 causes this value to be displayed on the display of the output unit 22. Alternatively, the credit value may be displayed on a display (not shown) of the card reader 18.

The card reader 18 may also read the identification code of the card. The customer can then operate the keypad to select a product for vending. Before the product is vended, the value stored on the card 26 is cancelled and an amount corresponding to the initial value minus the value of the vended product is written onto the card 26.

When the card reader recognises that a card has been inserted, it also writes audit data from the memory 24 to the data carrier portion of the card 26.

The amount of audit data stored by the memory 24 of the control means is typically larger than the amount of data storage available on a single card, and so in this embodiment the audit data is divided into blocks, and a block of data is written to the card.

The size of the blocks is chosen with regard to the storage capacity of a card usable within the system and the speed of the data transmission link between the control means and the card reader, so that a data block can be transferred to the card within a period of time that is acceptable to the customer.

In this embodiment, the payment card is held within the card reader 18 where it cannot be accessed by the customer until a block of data has been written to the card. Only after the data transfer is completed is the card returned to the customer. Alternatively, the card may be read in a position where it is accessible by the customer, but there is then a risk that the customer may remove the card before transfer of a block of data has been completed. In such a case, the transfer of the audit data may be performed before the credit data is displayed and the vend transaction takes place.

Each block of data is labelled. For example, suppose at a given time the audit data is divided into 9 complete blocks and 1 incomplete block, then the blocks are labelled in order as 1 to 10, where 10 is the incomplete block. Audit data increases with time, and accordingly the number of blocks also increases with time, each new block being labelled with the next integer.

In use, a single block is transferred to the payment card, together with the label of the data block, in this case, block 1, the time and date of the transfer, and a code indicating which vending machine has produced the data.

After the block of data has been transferred to the card, the card is returned to the customer. The customer may not be aware that audit data has been transferred to the card.

Similar steps to those described above are carried out each time a customer presents a payment card for a vend transaction. However, when a given data block is transferred in a given transaction, then the subsequent data block is transferred in the subsequent transaction, and so on, up to data block 10 in this embodiment. Then, for the next transaction, assuming that data block 10 is still the last data block, the card reader 18 returns to the beginning and transfers data block 1 to the payment card, and so on. This is carried out repeatedly so that each data block is transferred to several payment cards. When the audit data increases sufficiently that a new data block is created, then it is added to the sequence in position and written to the cards in turn.

In this example, the storage capacity of the payment card and the size of each data block is such that only one data block can be stored on the card. When a payment card 26 is already storing a data block, and it is used for other transactions in a vending machine, the card reader 18 recognises that a data block is already stored and does not attempt to write any additional data blocks.

However, in other embodiments, the payment card 26 may be able to store several data blocks. In such a case, the card reader 18 checks the labels of the data blocks already stored by the card and only writes the next data block in line to be written if it is different from those already stored. Alternatively, the card reader 18 may skip to the next block not already on the card 26 and write that block to the card 26.

Eventually, for a given payment card, the credit on the payment card will be reduced to such an extent that it is necessary for the customer to return to one of the revaluation terminals 10,12 and replenish the credit on the card.

At the revaluation terminal 10,12, the customer inserts the payment card 26. At this point, the revaluation terminal 10,12 reads and stores the block of audit data, together with the associated label, time, date and machine code from the card and deletes it from the card. The revaluation terminal 10,12 then writes a receipt for the particular data block to the payment card 26. A receipt is written by the revaluation terminals 10,12 each time a data block is received by the revaluation terminal 10,12, even if the data block has already been received by the terminal. The terminal then proceeds with the revaluation procedure in the usual manner.

Audit data received by the revaluation terminal 10,12 is sent to the system manager 14 through the network. At the system manager 14, the data blocks are combined and reassembled over time when they are received, using a suitable program, to obtain a complete picture of the audit data for each machine for a given time.

After revaluation as described above, the next time the payment card 26 is inserted into the card reader 18 of one of the vending machines 2a to 2n, the card reader 18 reads the receipt from the card 26. The control unit 20 checks if the receipt corresponds to a data block for the respective vending machine. If it does not, it is ignored. If it does, the receipt is deleted from the card 26 and the control unit 20 checks the memory 24 for the corresponding data block. If the data block is found, it is deleted, and thus it is no longer transferred to any further payment cards used in the vending machine. Alternatively, instead of deleting the block from the memory, transfer of the data block to payment cards may be inhibited, while the data block is retained within the memory 24, so that it can still be retrieved from the memory if necessary by other means. If the receipt corresponds to a data block that has already been deleted from the memory 24, because a receipt for that data block has already been received, no further action is taken. The data carrier application of the payment card is now freed, and a new audit data block is transferred to the card 26 as described above. In an alternative embodiment, the amount of data for the receipt and the size of the data storage on the card may be such that audit data can still be written to the card 26 even if it is carrying receipt data, say for a data block originating from a different vending machine. As the vending machine ceases sending data blocks that it knows have been received by the revaluation terminal, the probability that new data blocks will be received by the revaluation terminal is increased and thus the efficiency of the data transfer is improved.

The transfer of audit data and receipt data to and/or from a payment card as described above is carried out each time a payment card is presented to either a vending machine or a revaluation terminal. Also, the transfer of a given data block and a receipt for a given data block is carried out repeatedly, on different cards. Thus, at a given time, a particular data block may be stored on one or a plurality of payment cards which are in circulation. Furthermore, a receipt for a given data block may be stored on one or a plurality of payment cards. In time, as the cards are used in the vending machines and the revaluation terminals, audit data blocks are transferred from the vending machines 2a to 2n, to the system manager 14 by means of the payment cards 26 and the revaluation terminals 10,12 and data, in this example, receipts for the audit data, also flow in the opposite direction from the revaluation terminals 10,12 to the vending machines 2a to 2n.

A second embodiment, which is a modification of the first embodiment, will now be described. In the second embodiment, at each transaction in one of the vending machines, in addition to the audit data the machine also writes data to the payment card indicating which data block receipts the vending machine has received, to inform the revaluation terminals that they do not need to continue sending receipts for those data blocks. This is done, in this embodiment, by indicating a range rather than issuing individual acknowledgements for each data block receipt. More specifically, the card reader writes a number which indicates that, for all data blocks up to and including that number, the corresponding receipts have been received. Only a single number is used whatever the size of the range of receipts, thus reducing the amount of data to be sent compared with a situation where each receipt is acknowledged individually. This acknowledgement information is transferred on the payment cards to the revaluation terminals in a similar manner described to that above in Embodiment I in relation to the audit data. When the revaluation terminal receives the acknowledgement of a range of receipts, it stops sending any receipts within that range.

Similarly, in a variation of the first or second embodiment, in a third embodiment the revaluation terminal, instead of sending individual receipts for each data block, sends a receipt for a range of data blocks. For example, when a payment card is presented to a revaluation terminal and delivers a data block, the revaluation terminal writes to the card a number indicating that it has received all data blocks up to block p, say, which may or may not include the data block just read from the payment card. The revaluation terminal may write such receipt information for more than one vending machine to any given payment card.

A fourth embodiment of the invention will be described with reference to Figs. 3 to 7.

According to the fourth embodiment, as shown schematically in Fig. 3, three vending machines 30a, 30b, 30c are arranged on a site, for example, on a university campus. Each vending machine is capable of accepting payment from payment cards having either an electronic cash, a credit or a debit application. More specifically, unlike the first embodiment, there is no requirement that all payment cards used in the vending machines must be returned to one or more specific revaluation terminals. This is known as an "open"system. In contrast to the first embodiment, instead of collecting data by means of a revaluation terminal, in this embodiment, data relating to all three machines is collected in the third vending machine 30c, and sent from the third vending machine 30c to the bank 32. Confirmations of receipt of the transaction data are sent from the bank 32 to the machines 30a, 30b, 30c via the third vending machine 30c.

At least some of the payment cards 34 for use in the fourth embodiment have a data transfer application 36 in addition to the payment application 38.

Figs. 4 to 7 show schematically steps of the method of operation, according to this embodiment, described below.

Each time a payment card 34 is used for a transaction in one of the vending machines, a transaction record, shown in Fig. 4 as transaction n+5, is made and stored in the transaction store 40 for that vending machine 30a. The transaction record may include, for example, the account number of the debit card used with the amount charged as a result of the vend and the type of product selected. The bank uses the transaction record to transfer the appropriate amount from the cardholder's account to the account of the operator of the vending machine or of the supplier of the selected product. After the transaction has been completed, the card reader (not shown) in the vending machine 30a then writes transaction data about transactions that are stored in the transaction store 40 to the card 34 using the data transfer application. The transaction data written to the card may or may not include data about the transaction that has just taken place. In this embodiment, transaction data is transferred to the card in blocks, where each block corresponds to data for a single transaction. Each block of data is stored on the card with an associated header, which contains network management data, including source information such as details of which machine provided the data. The card reader writes as many complete blocks of data to the card as possible in the time before the card is removed from the card reader. As shown in Fig. 4, data for transactions n, n+1 and n+2 are written to the card during the time the card is within the machine for transaction n+5.

At the next transaction in the first vending machine with a payment card including a data transfer application, the machine will write transaction data starting from transaction n+3 and so on. During subsequent transactions, the machine cycles through the stored transaction data so that the data for each transaction is transferred to a multiplicity of cards. The machine also, however, takes account of what data the card is already carrying. For example, if a card is already carrying data for transactions n and n+1, the machine will skip those and proceed to write other transaction data to the card.

The second vending machine operates like the first vending machine to store transaction data and to write it to appropriate payment cards.

In time, a payment card storing transaction data is used in the third vending machine for a vend. Referring to Fig. 5, again transaction data relating to the specific transaction, here transaction m+9, is sent to the transaction store 43 for the vending machine 30c. In addition, the machine also reads the data stored in the data transfer application on the card and transfers data relating to any transactions it has not already received from the card to the transaction store 43. More specifically, as shown in Fig. 5, data for transaction m+9 is created and sent to the transaction store 43, and transaction data for transactions n, n+1 and n+2 is read from the data transfer application of the card.

Once a day, all the transaction data stored in the third vending machine is sent to the bank along a telephone link 45. Other means for transferring data from the third vending machine 30c to the bank may of course be used.

Once the bank has successfully received transaction data from the vending machine 30c, it sends confirmations to that machine along the telephone link. As shown in Fig. 6, the confirmation data is stored in a confirmation buffer 46 of the third vending machine 30c, for subsequent transfer to payment cards 34 used in the third vending machine 30c. Here, transaction data n, n+1 and m+9 has been successfully received and confirmed by the bank, but transaction n+2 was not successfully received, and so no confirmation for that is sent to the third vending machine 30c. If the third vending machine 30c receives a confirmation, then it deletes the corresponding transaction data from the transaction store 43; otherwise it keeps the transaction data and sends it to the bank again in the next batch.

The next time a payment card with a data transfer application is used in the third vending machine 30c after confirmations have been received from the bank the following steps are performed. The vending transaction is carried out, and then the transaction record, here transaction m+11, is stored in the transaction store 43. Then, any data stored in the data transfer application on the card is transferred to the transaction store 43, as described above. Next, confirmation data is written from the confirmation buffer 46 to the data transfer application 36 of the card 34, in the same manner as the transfer of transaction data in the other vending machines 30a and 30b. The confirmation data transferred to the card includes an identification of which vending machine the original transaction data came from. Similar operations take place for each card with a data transfer application used in the third vending machine 30c.

When a card is used in, say, the first vending machine 30a, referring to Fig. 7, after the transaction, transaction n+25, is performed and the transaction logged, the machine checks the data transfer application for any confirmations relating to its previous transactions. Any such confirmations are read to a confirmation buffer 48 and used to delete the corresponding transaction data from the transaction store 43 of the vending machine 30a, as indicated by the cross-hatched area in Fig. 7. Accordingly, those transaction data are no longer written to any cards. Next, the card writes transaction data which is still held within the transaction store 43 to the card 34, as described above. The amount of confirmation data stored in the third vending machine 30c will grow over time. Particular confirmation data may simply be deleted after it has been stored for a certain period of time, say 3 weeks. Alternatively, a serviceman may periodically remove the confirmation data from the vending machine 30c and then visit the other vending machines to perform the confirmations manually.

Alternatively, as in Embodiment 2, each of vending machines 30a, 30b may be arranged to send acknowledgements for the confirmations from the vending machine 30c.

As in the previous embodiments, the various steps of transferring data to and from payment cards including checking for transaction data and/or confirmations are performed each time a card with a suitable data transfer application is used in one of the vending machines. Thus, at a given time, various sections of data are being carried on a plurality of payment cards and various transfers are carried out at each vend transaction, as described above.

As described above, transaction and confirmation data are transferred in complete blocks of data. It is possible that only part of a block of data is written to a card before the data is removed from the card reader. In this embodiment, that block will be the first block to be written to the next card and it is written as a complete block. Alternative, it may be arranged that, when an incomplete data block is written, at the next transaction the remainder of that data is written rather than the whole block. Sufficient information to enable blocks to be reassembled from partial blocks is then also provided.

Various modifications to the embodiments described above are possible.

Some modifications are discussed below. It is to be noted that the various features of each of the above embodiments can be applied to the other embodiments as appropriate.

In the embodiments above, the data to be transferred is divided into data blocks each of a predetermined size. Alternatively, the data can be divided up into blocks according to different criteria. For example, one block may contain all the audit data for a given day. The data may be divided up into a first set of data blocks, and once those blocks have been written to payment cards, the data is then divided up into a different set of data blocks, which are of the same size but where the division starts from a different point. In that way, each new block overlaps with blocks from the previous set, but is not the same as any previous block. The new blocks are then written to the payment cards. Each block must contain sufficient information to enable the original total data to be reassembled.

Generally, after a certain period of time, a given block of data generated by the vending machine will have arrived at its destination and the acknowledgement will arrive back at the vending machine, whereupon the vending machine will stop transferring that block to payment cards. In that way, the flow of new data will be promoted. However, it is possible that sometimes the vending machine will not receive a receipt for a given data block. To deal with such an eventuality, the vending machines may be arranged to stop writing any given data block to the cards if a receipt for that block has not been received after a certain period of time, say, two months. The data block can be deleted, or archived in a memory. Preferably, the data transfer systems described above are supplemented by a manual system, where a serviceman visits the vending machines periodically, say once every three months to download audit data, and other data, stored in the vending machines. In that way, data blocks can still be recovered from the archive even if they were not successfully transferred by the payment cards.

The embodiments above have been described in the context of either an "open"or"closed"system. The invention and the embodiments are not limited to either arrangement. Also, a combination of the two, such as a system which is essentially closed, as hereinbefore defined, but where each vending machine also accepts a predetermined number of payments from electronic cash cards c via one or more machines linked to a system manager. Other examples of data that can be transferred include information about new prices for products together with information about the date on which such prices are to become effective, and"black list"data, that is information about cards, which may be lost or stolen, which should not be accepted.

The links between the revaluation terminals and the system manager, or between the vending machine and the bank, in the above embodiments, may be any suitable type of link, such as a telephone link, a network, an optical data link or a portable data storage means.

In the embodiments, data is transferred using payment cards in the form of multi-application smart cards. However, other types of data storage elements can be used, including a simple memory card.

The embodiments of the invention described above relate to payment cards and vending machines. However, the invention may be used in many different applications, and the invention is not limited to payment cards and vending machines. Cards are already used in many applications, and it is expected that they will become far more common in the future. A suitable data transfer application can be added to other applications on a card and used to collect any kind of data of interest from the machines in which they are used.

For example, identification cards that are swiped through card readers to obtain access to buildings or areas can be used to carry data stored in the card reader about other card use. The data can be collected from the cards when they are used at a central point, which might be, for example, the card reader at the main entrance to the buildings. Other examples include cards for obtaining access to a travel system such as the London Underground, loyalty cards such as those used in supermarkets, cards used in personal computers, such as cards giving authorisation to use the computer, and cards used in satellite decoders which can be used to transfer information about viewing habits.

Claims (34)

1. Claims: 1. A method of transferring data between at least a first machine and a second machine using a plurality of portable data storage elements individually insertable into said machines, the method comprising dividing the data into sections and writing a section of data to each of a plurality of said data storage elements so that the data is carried with redundancy.
2. 2. A method as claimed in claim 1 wherein a section of data is written repeatedly to a plurality of data storage elements.
3. 3. A method as claimed in claim I or claim 2 wherein different overlapping sections of data are written to different data storage elements.
4. 4. A method as claimed in any one of claims I to 3 wherein said data is written to and/or from the data storage element when it is presented to said first or second machine for a different purpose.
5. 5. A method as claimed in any one of claims 1 to 4 wherein the data storage elements are cards.
6. 6. A method as claimed in claim 5 wherein the data storage elements are payment media.
7. 7. A method as claimed in claim 6 wherein the payment media are for storing credit data representing monetary value.
8. 8. A method as claimed in claim 7 wherein the first machine is a terminal for increasing the amount of credit data stored on the element.
9. 9. A method as claimed in any one of claims 6 to 8 wherein the second machine is an automatic vending machine.
10. 10. A method as claimed in any one of claims 1 to 9 wherein the transferred data comprises audit data relating to the operation of a machine.
11. 11. A method as claimed in any one of claims 1 to 10 wherein the transferred data comprises a receipt for data.
12. 12. A method as claimed in any one of claims 1 to 11 wherein the transferred data comprises data relating to the configuration of a machine.
13. 13. A method as claimed in any one of claims 1 to 12 wherein data is transferred from a plurality of machines.
14. 14. A method of retrieving data transferred by a method according to any one of claims I to 13 comprising reassembling the original data.
15. 15. A system comprising at least first and second machines for receiving portable data storage elements individually insertable into said machines, and means for writing data to a plurality of said data storage elements so that the data is carried between the machines with redundancy.
16. 16. A system as claimed in claim 15 further comprising a plurality of data storage elements.
17. 17. A machine for use in transactions, the machine being operable to accept payment by decreasing the value of credit data stored on a payment card, the machine being operable to transfer data to a payment card presented to the machine for a specific credit transaction, said data being additional to the credit data for the specific credit transaction.
18. 18. A machine as claimed in claim 17 wherein additional data is stored in the machine and a portion of the total additional data is transferred to a payment card.
19. 19. A machine as claimed in claim 17 or claim 18 wherein the same additional data is transferred to a plurality of payment cards.
20. 20. A machine as claimed in any one of claims 17 to 19 wherein the additional data comprises audit data relating to the operation of the machine.
21. 21. A machine as claimed in any one of claims 17 to 20 wherein the additional data comprises data relating to a plurality of transactions carried out by the machine.
22. 22. A machine as claimed in any one of claims 17 to 21 wherein the additional data comprises a receipt for data.
23. 23. A machine for increasing the value of credit data stored on a card in return for payment, the machine being operable to transfer data additional to the credit data of the card, the additional data relating to the operation of at least one machine for use in transactions to which a card has been presented, from the card.
24. 24. A machine for use in transactions, the machine being operable to transfer additional data to or from a payment card presented to the machine for a specific transaction, the additional data being additional to data for the specific transaction.
25. 25. A method of transferring data between a machine operable to accept payment by diminishing the value of credit data stored on a payment card and a machine operable to increase the value of credit data stored on a payment card comprising transferring said data to said payment card when it is presented to one of said machines and transferring said data from said card when it is presented to the other of said machines, said data being additional to credit data.
26. 26. A method as claimed in claim 25 wherein data is transferred to a plurality of payment cards.
27. 27. A method of transferring a block of data comprising transferring the data block in sections to separate credit data-storing payment cards when the cards are presented to a machine for changing the stored credit data.
28. 28. A method as claimed in claim 27 wherein each section is transferred to multiple cards.
29. 29. A method of retrieving data which has been transferred in sections to multiple credit data-storing payment cards comprising reading the sections from the payment cards when they are presented to a machine for changing the stored credit data.
30. 30. A method of retrieving data which has been transferred in sections to multiple credit data-storing payment cards comprising reassembling the total data from a plurality of sections of data.
31. 31. A system for transferring data using payment cards for storing credit data comprising at least one machine for increasing the value of credit data stored on a payment card and at least one machine for decreasing the value of credit data stored on a payment card, wherein at least one type of said machines is operable to transfer additional data to a payment card when it is presented to that machine for a credit transaction and at least one of the other type of said machines is operable to transfer additional data from a payment card when it is presented to that machine for a credit transaction, said additional data being additional to the credit data for the specific credit transactions.
32. 32. A system as claimed in claim 31 wherein at least one type of said machine is operable to transfer additional data to and from a payment card.
33. 33. A machine for use in transactions substantially as hereinbefore described with reference to the accompanying drawings.
34. 34. A method of transferring data substantially as hereinbefore described with reference to the accompanying drawings.