Abstract: A circuit for determining connection status of a phone line shared by multiple telecommunications devices, such as modems and phones, is provided. The phone line includes respective tip and ring lines. The circuit comprises a first transistor stage coupled to receive a signal indicative of a voltage difference between the respective tip and ring lines. The first transistor stage is configured to supply an output signal having a predetermined time response. The circuit further comprises a second transistor stage coupled to the first transistor stage and configured to supply an output signal having a slow time response relative to the output signal from the first transistor stage.

Abstract: A field-testable integrated circuit that includes a plurality of analog signal channels for receiving a respective analog signal during a normal mode of operation is provided. Individual test circuits are built-in within the integrated circuit for selecting respective ones of the plurality of channels to receive predetermined reference signals during a test mode of operation while uninterruptedly providing the normal mode of operation in any remaining unselected channels. Each test circuit includes a channel decoder responsive to predetermined channel select signals for producing a respective channel decoder output signal. A multiplexer is responsive to predetermined reference select signals and to the decoder output signal for supplying during the test mode of operation a selected one of the predetermined reference signals to the respective analog channel being coupled to the individual test circuit therein.

Abstract: In order to solve the problem of the proximity effects which occurs in the fabrication of integrated circuit devices, a facile method is provided for automatically creating a new pattern in which variably spaced windage correction is applied over the mask. This permits the utilization of conventional design fabrication rules and systems without the concomitant problem of producing small feature sizes in isolated structures. The method produces highly desirable chip masks and is readily implemented on commercially available CAD systems presently being employed for the production of circuit masks. The method is automatic and extremely easily implemented.

Abstract: A method is described for forming a desired pattern in a layer of polymethyl methacrylate resist formed on a substrate by irradiating the layer with a pattern of radiation substantially identical to the desired pattern and thereafter immersing the layer of polymethyl methacrylate in a solution of acetone to remove the irradiated portion of the layer of polymethyl methacrylate.