International Business Machines Corporation

Jon E Fox

Kian-Bon K Sy

Fuyung Lai

Daniel S Abensour

Phillip R Epley

Mehendra J Joshi

Mahendra J Joshi

Jerome P Dahl

Fu-Yung Y Lai

The system and method of the present invention provide a seamless approach for providing ATM connectivity for a Frame Relay DTE using an intelligent Terminal Adapter (TA). Using the system and method of the present invention, an enhanced Frame Relay protocol runs between the DTE and the ATM TA, the Frame Relay DTE is provided with not only the connectivity to the ATM network but also the full advantages of ATM transport mechanism. For instance, the FR DTE can choose to transmit its data using ATM Adaptation Layer (AAL) 1,3/4 or 5. Using the system and method of the present invention, a FR DTE may communicate with another FR DTE or to an ATM DTE through wide area or local area ATM network. The Frame Relay DTE can send data, image, voice, or video traffics across the ATM network via the FR/ATM terminal adapter.

System and method for providing ATM support for frame relay DTEs with a

A terminal adapter interfaces between a Data Terminating Equipment (DTE) and either a Frame Relay or a Switched Multimegabit Data Service (SMDS) telecommunications network so that the type of network over which the DTE is communicating is transparent to the DTE. The terminal adapter performs mapping from one protocol to another so that a native frame relay DTE can access an SMDS network and so that a native SMDS DTE can access a frame relay network. The address mapping method performed by the terminal adapter uses a parallel table look-up technique which reduces the chance of collision (when two or more addresses hash into the same table entry), eliminates the traditional comparison function to detect a collision, and eliminates the traditional pointer technique when a collision occurs.

Combined terminal adapter for SMDS and frame relay high speed data

A sensing apparatus for detecting impedance changes in a variable impedance matrix keyboard. A microcomputer is utilized to control the basic key intersection scanning and for accurately calibrating and adjusting the sensing threshold of the sense amplifier prior to testing each key intersection so that the effects of stray impedance and varying voltage levels may be compensated for. The micro computer supplies sense amplifier sensitivity threshold selection address codes to set the sensing level for the amplifier. Trial drive pulses are applied to a reference capacitor and are gated to the sense amplifier while the sensing level thereof is varied until no output is obtained. This effectively adjusts the sensing circuits for variable voltage power fluctuations occurring over a short time and compensates for variable capacitive effects not associated with actual key switch movements. The micro computer also has a memory containing known stray capacitance values associated with a given keyboard design and these values are also used to compensate by modifying the sensing threshold above or below the calibrated sensing level achieved. Thisis done after driving and measuring the capacitance response until a zero output is obtained so that the sensing level may be individually set for each given key in the matrix at that precise level which can provide the highest non-saturating sensitivity level for the amount of stray capacitance known to be associated with the key and for the existing power and capacitance conditions as originally determined by checking the reference capacitor.

Program controlled capacitive keyboard variable threshold sensing system

Growing community of inventors

Cary, NC, United States of America

Jon E Fox