Abstract: The disclosed communication system enables communications between reconfigurable data terminals and a variety of connected computers, having dissimilar operating parameters, by automatically reconfiguring the operating parameters of the calling terminal to match those of the called computer. The system controller, in response to receiving the dialed number of the called computer from the calling terminal, accesses its memory for the operating parameters of the called computer and transmits these operating parameters to reconfigure the calling terminal. Another embodiment enables the operating parameters of a terminal to be reconfigured in any of a number of operating modes in response to a reconfiguration request signal sent to the system controller from the terminal.

Abstract: The UNIX.RTM. and MS-DOS.RTM. operating systems are supported in a multi-tasking computer. At the heart of the computer is a microprocessor having protected and non-protected modes. The computer includes special-purpose hardware which prevents the MS-DOS system and its applications, which execute in the non-protected mode, from interfering with the UNIX system and its applications, which execute in the protected mode. In particular, this hardware monitors addresses generated by the computer and, by selectively inhibiting the associated control pulses, prevents the MS-DOS system from, for example, writing in UNIX-system-allocated memory, or accessing I/O devices that the UNIX system is currently using. In addition, a context switching feature is provided whereby the user can select, via a keyboard operation, to have displayed on the computer video monitor at any given time the image generated from the current UNIX system screen data or the image generated from the current MS-DOS system screen data.

Abstract: The UNIX.RTM. and $MS-DOS sup R $ operating systems are supported in a multi-tasking computer. At the heart of the computer is a microprocessor having protected and non-protected modes. The computer includes special-purpose hardware which prevents the MS-DOS system and its applications, which execute in the non-protected mode, from interfering with the UNIX system and its applications, which execute in the protected mode. In particular, this hardware monitors addresses generated by the computer and, by selectively inhibiting the associated control pulses, prevents the MS-DOS system from, for example, writing in UNIX-system-allocated memory, or accessing I/O devices that the UNIX system is currently using. In addition, a context switching feature is provided whereby the user can select, via a keyboard operation, to have displayed on the computer video monitor at any given time the image generated from the current UNIX system screen data or the image generated from the current MS-DOS system screen data.

Abstract: A light-transmissive device, illustratively a glass plate, is disposed adjacent to a plurality of light-emissive pixel locations, illustratively the pixel locations of a cathode ray tube (CRT). The glass plate entraps light originating from the CRT at least when an object, such as a document, is placed on one of the surfaces of the light-transmissive device, the amount of light that is entrapped being a function of the reflectivity characteristics of the document. The pixel locations are successively energized and a light detection signal indicative of the level of the entrapped light is generated by photodetection circuitry disposed adjacent to the edge of the glass plate. A pixel signal is stored for each energized pixel location, that signal being a function of the level of the light detection signal during the time that that pixel location was energized. The ensemble of stored pixel signals can then, for example, be displayed.