Browse Prior Art Database

Video Terminal Controller

IP.com Disclosure Number: IPCOM000043869D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Mehta, MA: AUTHOR [+3]

Abstract

A technique is described whereby a single device, a Video Terminal Controller (VTC), is used as an interface to interconnect a keyboard and monochrome/color display to a central processing unit. The VTC supports high speed communications via an RS-422 direct connect interface at distances up to 4,000 feet and at communication speeds of up to 9600 baud. Also, the VTC supports long distance transmission over telephone lines at communication speeds of up to 1200 baud, a display and keyboard, and printing capability via a parallel port. Multiple VTCs permit multiple keyboard/display printer support. The VTC, as shown in the drawing, consists of a microprocessor 10, a video controller 12, keyboard interface 14, serial communication interface 16, and printer interface 18. Also included are the necessary power supply and connectors.

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Video Terminal Controller

A technique is described whereby a single device, a Video Terminal Controller (VTC), is used as an interface to interconnect a keyboard and monochrome/color display to a central processing unit. The VTC supports high speed communications via an RS-422 direct connect interface at distances up to 4,000 feet and at communication speeds of up to 9600 baud. Also, the VTC supports long distance transmission over telephone lines at communication speeds of up to 1200 baud, a display and keyboard, and printing capability via a parallel port. Multiple VTCs permit multiple keyboard/display printer support. The VTC, as shown in the drawing, consists of a microprocessor 10, a video controller 12, keyboard interface 14, serial communication interface 16, and printer interface
18. Also included are the necessary power supply and connectors. The microprocessor section supplies all control signals, device selection, drivers, and receivers required to communicate with external interface sections of the VTC. The microprocessor is interrupt driven and operates from programs stored in read-only memory (ROM) 20. The VTC supports three types of monitors: 1) a direct drive monochrome monitor, 2) a direct drive color monitor, and 3) a composite video TV monitor. The keyboard interface 14 is capable of receiving an eight-bit scan code when a key is depressed. The keyboard interface 14 provides deserializing circuitry, stepped by a clock, so that when a keyboard s...