Abstract: A method and system for article selection and purchase in a retail establishment utilizes customer selection of articles from a plurality of display panels displaying samples of the articles. Information including customer identity, article selection and article quantity is provided to the system by entry devices on the display panels. A record of customer selections is generated at a precheck terminal using this information, which is also used to transport the selected articles from a product stocking area to an order accumulation area, where a record is made of the accumulated articles. The two records are compared at a finalizing terminal, where customer payment is received and the purchased articles are delivered to the customer.

Abstract: An interrupt control unit which couples a plurality of peripheral devices to a central processor includes a counter for outputting signals for monitoring a plurality of encoders each coupled to a number of peripheral devices, each encoder outputting the address of a requesting peripheral device when enabled. A memory unit outputs the address of the highest priority peripheral device for each output signal of the counter and a comparator compares the address of the peripheral device having the highest priority access outputted by the memory unit with the address of the previously interrupting peripheral device to determine priority access to the central processor.

Abstract: An adapter for use with a host processor for processing interrupts between a host processor and a plurality of remote data terminal devices is disclosed. The adapter includes a microprocessor, counter means which is incremented by a clock for sequentially interrogating a plurality of remote data terminal devices to determine whether or not a remote device is requesting access to the host processor and an external buffer for storing the output of the counter. The output of the counter is transferred to the microprocessor upon the sensing of a request signal for use by the microprocessor in identifying the requesting remote data terminal device and for processing the data from the requesting device to the host processor. The operation of the counter means is controlled by the microprocessor in accordance with the availability of the microprocessor to service the requesting data terminal device.

Abstract: Communications between processor terminals are carried out through the use of communication adapters. Each adapter receives selected control signals for transmitting or receiving data over a serial communication link to or from a remote terminal. The transmission portion of an adapter includes pretransmission control circuitry which receives control signals and stores transmission control signals which are used to control the format and serial transmission of a frame of data to a remote terminal. Each frame of data is begun and terminated with a uniquely encoded flag byte. Following the first flag byte are successive address and control fields. An optional information field may follow the control field and may include encoded information designating a dynamic change in the byte size of the data.

Abstract: A technique and implementation of generating and supplying synchronization and error checking signals to a serially transmitted data stream includes the generation of flag bytes which define the end boundaries of the serial data stream, an abort character for aborting the transmission of a frame of data in response to certain conditions, and a diagnostic evaluation character inserted into the data stream. In addition, the invention provides a technique for ensuring that the unique binary code by which a flag byte is defined occurs in the transmitted data stream only where intended. The flag code has been chosen to contain a prescribed number of consecutive one bits, (i.e. -- six) flanked by zeroes, and circuitry monitors the contents of a data frame as it is being serialized out for transmission to a remote terminal at times other than during flag transmission.