| 摘要 |
<p>A portable token, containing a storage circuit capable of being re-written, adapted to store a representation of a monetary value (a "credit"). Such representation being in a number-complement form, that is, the value being represented as the difference between the highest number which can be represented in the given storage, and the value actually intended to be represented. The said token being so adapted as to accept the input of a second number, said second number being in normal arithmetic representation, constituting the cash-value of a "charge" which it is desired to apply against the stored credit aforesaid. The application of said "charge" being made by performing a normal arithmetic addition upon the stored value, and the said "charge" number. The appearance of a "carry" at the conclusion of such addition (i.e. denoting that the resulting sum is too large to store in the available storage means) serving to denote an invalid charge, said "carry" serving both to inhibit any alteration of the said stored credit value, and to indicate to an associated reader means, that the attempted transaction may not proceed.</p> |
