Apparatus for bridging between two local area networks is disclosed. The apparatus has two bridge sides each including means for receiving or transmitting a message frame, controller means for directing an incoming message frame into a memory means shared between the bridge sides or directing a frame out of the memory means for transmission, address reading means for reading an address portion of the incoming frame and processor means for determining frame transmissibility from the address portion as provided by the address reading means. The apparatus is configured such that the processor means determines incoming frame transmissibility substantially concurrent with the controller means directing the incoming frame into the memory means.

A processing circuit executes a data producing process and a data consuming process. The data producing process produces a stream of data, the data consuming process consumes the stream of data concurrently with production of the stream. A first-in first-out buffer passes data from the stream between the data producing process and the data consuming process. The buffer comprises buffer memory, the buffer writes data-items from the stream in circular fashion into the buffer memory. A consuming process interface is arranged to process a command for making a data grain from the stream available to the data consuming process. The interface responds to the command by testing whether addresses of data within the grain to which access has to be gained wrap around in the circular FIFO buffer. The interface copies the grain from the FIFO buffer to the auxiliary memory region, on condition that the addresses wrap around, so that the wrap around is eliminated in the copied grain, The interface returns an indication to the consuming process to read the grain from the FIFO buffer when the addresses do not wrap around inside the grain, or an indication to read from the auxiliary memory region, when the addresses wrap around.

A software buffer is implemented without using notoriously slow locking mechanisms by employing a so-called atomic microprocessor operation to increment a counter tracking the total number of messages inserted into the buffer by various processes. In this manner, a unique slot is guaranteed to be assigned to each respective message to be inserted. Additionally, a count of the total number of removed messages is used to handle situations where two messages are assigned the same slot due to buffer overflow.

A simplified bus interface circuit for stores applications includes on-chip pseudo-dual port memory that is user-configurable into receive and transmit portions that are further separable into blocks associated with various sets of commands by means of a pointer set of assignable pointers. The circuit provides for echo-back comparison of transmissions and confirmation, in the case of RT to RT commands that the correct terminal has initiated a message.

A method and apparatus for distinguishing and separating material items having different levels of absorption of penetrating electromagnetic radiation by utilizing a source of radiation for irradiating an irradiation zone extending transversely of a feed path over which the material items are fed or passed. The irradiation zone includes a plurality of transversely spaced radiation detectors for receiving the radiation beams from the radiation source. The material items passing through the irradiation zone between the radiation source and the detectors measures one or more of the transmitted beams in each item passing through the irradiation zone to produce processing signals which are analyzed by signal analyzers to produce actuated signals for actuating a separator device in order to discharge the irradiated items toward different locations depending upon the level of radiation absorption in each of the items. One example of material items which have been successfully separated are recyclable plastic containers, such as polyester containers and polyvinyl chloride (PVC) containers.