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Display Monitor Detection and Self Configuration for Personal Computer

IP.com Disclosure Number: IPCOM000039513D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Rodriguez, L: AUTHOR [+2]

Abstract

A technique is described whereby video driver circuitry automatically determines four different types of display monitor configurations attached to a personal computer. The concept differs from prior art in that the setting of a dip switch is eliminated for four different types of monitor configurations. Since each monitor has a unique input terminator circuit at both the horizontal and vertical synchronization input signal sections, video driver 10, as shown in the figure, uses a bidirectional transceiver circuit for the same signals. In normal operation, video driver 10 sends out a horizontal and vertical sync signal derived from the respective drive signals in order to maintain the CRT display in synchronization with the video outputs.

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Display Monitor Detection and Self Configuration for Personal Computer

A technique is described whereby video driver circuitry automatically determines four different types of display monitor configurations attached to a personal computer. The concept differs from prior art in that the setting of a dip switch is eliminated for four different types of monitor configurations. Since each monitor has a unique input terminator circuit at both the horizontal and vertical synchronization input signal sections, video driver 10, as shown in the figure, uses a bidirectional transceiver circuit for the same signals. In normal operation, video driver 10 sends out a horizontal and vertical sync signal derived from the respective drive signals in order to maintain the CRT display in synchronization with the video outputs. In order to detect the type of monitor attached to the system, outputs 11 and 12 of video driver 10 are placed in a high impedance state. The personal computer processor reads the monitor sense port, which is wired to the horizontal and vertical input/output signal lines 13 and 14, so that software may use the information to configure the video driver. Input circuits 11 and 12, connected to input terminator 15, consist of pull-up or pull-down resistors
R. Logic states are assigned as follows: Monitor types A, B and C have different attributes, such as color or monochrome, and different horizontal sweep frequencies. The fourth state (1,1) may be used to determ...