Abstract: A method and apparatus for measuring isotherms comprising a two-pressure and/or two-temperature humidity generator having a temperature controlled internal chamber and a microbalance mounted externally such that the mass of a sample suspended within the chamber can be determined without disturbing the controlled environment surrounding the sample. The two-pressure humidity generator has a front panel for controlling humidity and temperature within the internal chamber and an access port that extends into the internal chamber. The balance is situated near the port such that the balance mechanism extends within the internal cheer. The balance mechanism utilizes a means for holding a sample within the chamber such that the mass of the sample can be determined as it equilibrates to the temperature and relative humidity maintained within the internal cavity.

Abstract: A controller for a communication system having a plurality of networks and a plurality of stations communicating with each other by sending messages from a source station to a destination station is disclosed. A plurality of stations may be assigned to a group. A communication history for the stations is determined, where the history corresponds to the messages communicated. The stations are connected into a common network in accordance with the communication history. The communication history corrresponds to a series of packets and is based on a source address and a destination address of each of the packets. A station may have a matrix, the matrix having rows indexed by source system address and columns indexed by destination system address, for storing a value indicating a quantity of information transferred from each station to each other station.

Abstract: A data communication system having a plurality of nodes is disclosed. A number of transceivers is provided, each transceiver being coupled to a respective one of the plurality of nodes, for data communication between the transceiver and its associated node. Each transceiver is also provided with a controlled current source. The data communication system is also equipped with a data bus for communication of a transmitted data signal between the transceivers. A current bus which is coupled to each transceiver receives a current signal from the controlled current source when a transceiver is placing the data onto the data bus.

Abstract: Transceiver apparatus includes a transmitter circuit constructed with either emitter coupled logic (ECL) circuitry or programmable array logic circuitry, and a receiver circuit constructed with ECL circuitry. The transmitter circuit encodes a binary data signal received for transmission as a three-level modified duobinary encoded data signal and the receiver circuit decodes the received three-level encoded data signal to provide a binary data signal corresponding to the data signal received at the transmitter circuit for transmission. Both the transmitter and receiver circuits include features enabling transmitting and receiving high data-rate data signals.

Abstract: A system for determining the physical location of nodes on a network. The system includes two stations each of which has a clock. Each station uses its clock to determine the arrival times at the station of a packet transmitted over the network from a first node to a second node and of a reply packet sent by the second node to the first node. The arrival times of the packets and the corresponding reply packets are then used to calculate the distance along the network which separates the first and second node. Measurement of packet arrival times for all of the nodes yields the position of all of the nodes on the network.

Abstract: A computer network interface ("NIC") exhibits reduced electromagnetic interference and emission through capacitively coupling an output transformer center tap both to reference ground and to logic ground of the NIC's transceiver. Transmit signal lines on both sides of the transceiver are also capacitively coupled to both grounds. Other aspects of the invention reduce electromagnetic interference and emission through improvements in the construction of the NIC printed circuit board and the technique for intercoupling a plurality of NIC's using shielded twisted-pair cable.

Abstract: A squelch circuit is disclosed that distinguishes between noise impulses and valid packets of data transmitted over a transmission line such as a twisted pair media within a local area network. The squelch circuit converts supplied data into a stream of positive and negative pulses and detects a sequence of positive and negative pulses quantified in time based on prior knowledge of the characteristics of a valid packet of data and permits the supplied data to pass if it has the characteristics of a valid packet of data or prohibits the supplied data from passing if it does not have the characteristics of a valid packet of data.

Abstract: A pass-through and isolation switch for connecting a terminal to a computer and for disconnecting the terminal from the computer without disrupting any sessions which may have been opened on the computer by the terminal. The switch includes a first gate and a second gate for switching in and out balanced termination loads across corresponding input terminals of the switch depending on the state of a control signal. And it includes a third gate and a fourth gate for preventing or allowing the passage of signals between the terminal and the computer, also depending upon the state of the control signal.

Abstract: An adapter for allowing high frequency local area network signals to be transmitted over low cost twisted pair cable. The adapter performs two functions, to act as a converter to match the impedance of the coaxial cable to that of twisted pair cable, as well as an output balancer, to insure that the alternating current or high frequency components of the signals sent over the twisted pair cable are complementary. Only one of the complementary signals carries DC collision information.

Abstract: A coffee making apparatus is disclosed for automatically mixing instant coffee and for maintaining the coffee hot during dispensing thereof. The coffee is housed within an urn similar to that utilized for drip coffee although simpler in construction and designed specifically for instant or freeze-dried applications. Provisions are also made for dispensing hot water.