The authors present an MC68000-based computer and the interfaces that allow its use as a point-of-sale unit and make it possible to remotely reprogram system parameters through a regular telephone line. The terminal is capable of reading different types of magnetic cards (i.e., credit cards, debit cards, etc.), obtaining an approval code, requesting remote information about the user, and printing receipts, among its basic functions. The hardware and software design considerations are discussed. The use of microcontrollers is shown to perform data entry and enhance the printing speed of the system. The system presented is a modular system, since upgrading can be performed very easily. The modularity of the software allows the system to operate in a multitasking scheme, making it suitable for real-time applications.
