A method and apparatus are provided for updating or changing configuration data stored in the PROM of a target system, the data being used to configure one or more reprogrammable logic devices such as FPGAs. In one embodiment the apparatus comprises a modem used to communicate remotely with a host system, a shadow PROM for receiving new configuration data intended for use in a target system, an interface for relaying configuration data from the shadow PROM to the target, and means for controlling the components of the update system.

A method of executing communication programs in a modem apparatus. A plurality of communication programs used to perform data communication or facsimile communication are stored in an internal memory space (e.g., ROM) in a processor after they have been compressed. A communication program to be executed in ROM is decompressed and developed in a work area external to the processor (e.g., RAM). The developed communication program is then executed by the processor. The data decompression is performed according to an exclusive program decompression program or a program in the communication programs which is adapted to provide a data decompression function.

A terminal unit of the present invention and applicable to a wired services network distinguishes two or more different kinds of plugs possibly connected to its general-purpose modular jack, reads a particular protocol matching the plug out of its storage, and then sets the protocol as its own protocol. Therefore, a plurality of data terminals each having a particular protocol can share a single terminal unit. In addition, a protocol adequate for a desired data terminal can be automatically set. This enhances the convenient use of terminal equipments.

A system permits the shared use of lines in a cursor control device coupled to a PS/2 interface or a serial interface. A computer pointing device such as a mouse can be coupled to either the PS/2 interface or the serial interface. The current supplied by the serial interface is limited by conventional circuitry within the interface itself. However, a clock line, normally used when the pointing device is coupled to the PS/2 interface, can be used to supply additional current to the pointing device when coupled to a serial interface. A Schottky diode is coupled in series between a V.sub.cc /RTS line and a power supply node within the pointing device. A second Schottky diode is coupled from a CLK/DTR line to the power supply node. When the pointing device is coupled to the PS/2 interface, the first Schottky diode provides current from a V.sub.cc source within the PS/2 interface. The second Schottky diode is not active when the pointing device is coupled to the PS/2 interface. When the pointing device is coupled to the serial interface, both the first and second Schottky diodes are active and both supply current to the power supply node. The first Schottky diode also prevents reverse current flow during initialization of the serial interface.

Devices and methods to monitor a distributed system for supplying goods or services and to generate messages concerning the state of the system and the supplied goods or services, Two-way communication within the system occurs between remote local units and a host computer in a control and information processing center. The local units are equipped with a microcontroller with a memory coupled to a plurality of sensors that detect the occurrence of and provide information regarding specified events, such as sales of goods, unauthorized entry into the local unit, and notification of low inventory stock.