Browse Prior Art Database

Variable Resolution RGB Color Video Sampler

IP.com Disclosure Number: IPCOM000038779D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Bailey, WP: AUTHOR

Abstract

This article describes an interface for coupling an RGB video color terminal to a color printer using the EIA (Electrical Institute Association) RS343 standard interface. The disclosed interface adapts to video terminals and printers having variable resolutions. (An RGB terminal is a color terminal or monitor that has separate red, green, and blue color input signals as contrasted to a composite video signal which combines the color signals into a single signal requiring subsequent separation before they can be displayed.) Hard copy of the color video display screen is made on color printers, commonly driven via the RS343 interface. The printer must have the capability of printing at the same resolution as the color video display.

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Variable Resolution RGB Color Video Sampler

This article describes an interface for coupling an RGB video color terminal to a color printer using the EIA (Electrical Institute Association) RS343 standard interface. The disclosed interface adapts to video terminals and printers having variable resolutions. (An RGB terminal is a color terminal or monitor that has separate red, green, and blue color input signals as contrasted to a composite video signal which combines the color signals into a single signal requiring subsequent separation before they can be displayed.) Hard copy of the color video display screen is made on color printers, commonly driven via the RS343 interface. The printer must have the capability of printing at the same resolution as the color video display. In the prior art, the printer and interface must be changed if a terminal with a different resolution were used. The circuit described below provides an interface for varying resolutions. The interfacing circuit between the RS343 standard bus and the microprocessor bus is shown in the figure. A variable frequency clock is adjusted to a frequency determined by the resolution of the printer. The clock signal controls a sample-and-hold circuit that makes the interface independent from the resolution of the driving device. The frequency of the clock circuit is set by changing the value of the frequency control capacitor C. The clock signal drives a circular shift register that supplies an output control signal at a frequency which is further adjustable by offset values from the microprocessor- supplied bus signal and the frequen...