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Browse Prior Art Database

Monitor Identification Range Extension

IP.com Disclosure Number: IPCOM000102301D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 29K

Publishing Venue

IBM

Related People

Canton, DA: AUTHOR [+2]

Abstract

A conventional VDU monitor identification scheme can only indicate fifteen unique monitor types. As most allocations are taken-up, an extension is required until new interface architecture can be introduced.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Monitor Identification Range Extension

       A conventional VDU monitor identification scheme can only
indicate fifteen unique monitor types.  As most allocations are
taken-up, an extension is required until new interface architecture
can be introduced.

      This monitor identification scheme can be extended by
recognizing four states or conditions on one of the identification
pins rather than the two states currently employed.  The states
presently employed are logic 1 and 0. The proposal is that two extra
states of HSync and VSync be introduced.  The adapter is responsible
for timing any transitions on the most-significant ID pin and
determining which of the four states is present.  This may be
performed in either hardware or software.

      HSync or VSync can be hard-wired to ID bit 3 inside the monitor
connector so no extra logic or wires are required in the cable,
neither are any hardware changes required in the display adapter.
Sixteen additional ID codes become available, and the extension
scheme does not require the monitor to be powered on.  By using only
this 4-state scheme on ID bit 3, the scheme is compatible with the
8514/A which only looks at ID bits 0-2. It will be appreciated,
however, that the same scheme could be applied to the other ID bits.