Abstract: This paper describes small cash systems and the use of iButton® SHA devices, specifically, the DS1963S and DS1961S, as the electronically readable tokens in which the cash is stored. Two scenarios are presented. In scenario A, both the tokens and the coprocessor are DS1963S iButtons. In scenario B, the DS1963S functions as coprocessor in a system that uses the DS1961S as tokens or carriers of electronic cash. White Paper 1 SHA Devices Used in Small Cash Systems www.maxim-ic.com INTRODUCTION Paying for products in the store is easy and convenient, provided that the store accepts "plastic money" and the convenience fee doesn't cut too deeply into the profit of the merchant. Naturally, for small purchases plastic is not accepted, which throws the customer back into the age of paper money and coins. Traditional vending machines operate on coins only. As prices for products and services increase the probability of having the right selection of coins on hand decreases. The……