Honeywell Information Systems Inc.

Microcom Systems, Inc.

Hewlett-packard Development Company, L.p.

Microcom Corporation

Jerry Falk

Richard A Carey

Lewis A Bergins

Michael F Onorato

Dennis Kloc

Roy Greene

Anthony P Amundson

An improved system for the transmission of data over a cellular telephone channel is provided. The system is especially adapted to reduce the cost associated with cellular telephone calls by allowing data transmission only when the channel signal level is greater than a pre-defined value, so as maximize the probability that a transmission will be successful. In addition, the system provides for user transparent reconnection and reestablishment of a dropped link, allowing transmission to continue where dropped without the need to retransmit data already successfully received. As an additional benefit, the system provides a mechanism for call timing and billing so that an estimated bill may be generated based on connection time.

Transmission of data over a radio frequency channel

A data telecommunications system and method is provided for sending a data stream of characters in distinct data packets between two units of data terminal equipment (which can be either terminals and/or computers) connected over communication lines. A modem is connected between each unit of data terminal equipment and the communication lines, and one initiating modem includes a means for changing the packet size of the data which is transmitted. The receiving modem checks the packets for errors, and if errors are found, the packet is retransmitted. The initiating modem counts the number of transmissions of data packets as well as the number of retransmissions of data packets. A ratio of retransmissions to transmissions is used to determine the optimum packet size. The packet size is continually subject to change as the ratio changes during transmission.

Method and apparatus for transmitting data in adjustable-sized packets

An interactive terminal computer system is disclosed having a system bus for communicating between elements of the computer system which has apparatus for permitting the execution of a maximum number of concurrent bus cycles without interference with each other.

Apparatus for maximizing bus utilization

An interactive computer terminal system having a bus for communication between elements of the system is disclosed having apparatus for assigning control of the computer bus on a predetermined order of priority. The CPU receives requests from computer system elements and assigns time slots for use of the system bus by arbitrating among various resources competing for access to the bus.

Bus arbitration logic

An interactive terminal includes a central processor unit (CPU) having a microprocessor and a random access memory (RAM). Signals from the microprocessor place the RAM in a write protect mode. If the RAM receives a write instruction from the microprocessor when the RAM is in the write protect mode, then an illegal condition is indicated and a nonmaskable interrupt is generated to allow the terminal to recover. When the RAM is in the write protect mode, signals from the microprocessor restore the RAM to its normal read/write mode.

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Medway, MA, United States of America

Jerry Falk