The eXtended Graphics Adapter [XGA] interface was developed by IBM and was
used as an interface between a Personal Computer
and a Monitor.
The XGA interface was introduced in 1990 and no longer in common usage. The VGA interface provided a
resolution of 1024 x 768 pixels.
The XGA Interface bus uses a high density 15-pin D-sub connector. The table below provides the pin-out and signal names for
the DB15-pin connector.
The 1990 release date indicates two things; first the standard is obsolete and the second the signal assignments are fixed and will never change.
Of course analog monitors are out-dated, and the Red, Green, Blue signaling, used here, have been replaced by digital signals.
The connector may be advertised having a number of different options, or use particular terms to describe it.
Assuming a 15-pin XGA connector on both the Monitor and PC; the cable will indicate 15 pins.
The 15-Pin connector will have 3 rows of 5 pins or sockets per row. HD DB15 Insert Arrangements.
DB is the family, HD [High Density] is the style, M is Male[Pins], F is Female [Sockets].
Normally Equipment [PCs and Monitors] use sockets, so the cable needs to have pins [Male] to mate with the device.
A normal cable may indicate HD15 Male to HD15 Male, or DB15 Male to DB15 Male, or high-density DB15 connector.
In some cases the connectors may be called a mini-sub D15.
The length of the cable will vary depending on the quality, the better the cable is made the longer the length.
When the cable uses a 15-pin connector and indicates a certain resolution then it may also comply with the SVGA standard.
A shielded cable is better then a non-Shielded cable and of course more expensive.
The cable may also indicate it contains EMI beads to reduce noise, again
it may be a higher quality cable.
Note that there is a non-high density DB15 connector, Dual-Row DB-15 Connector but was never used much.
A listing on OEM D-sub connector manufacturers may be found on the
Connector
Manufacturers page, and this page points to Cable Assemblies.
Pin # | name | Description |
---|---|---|
1 | RED Video | Red Video |
2 | GREEN Video | Green Video |
3 | BLUE Video | Blue Video |
4 | ID2 | Monitor ID, Bit #2 |
5 | Test | Self Test |
6 | RGND | Red Ground |
7 | GGND | Green Ground |
8 | BGND | Blue Ground |
9 | Key | No pin installed |
10 | SGND | Sync Ground |
11 | ID0 | Monitor ID Bit #0 |
12 | ID1 | Monitor ID Bit #1 |
13 | HSYNC | Horizontal Sync |
14 | VSYNC | Vertical Sync |
15 | ID3 | Monitor ID Bit #3 |
Related Video Interfaces;
MDA [Monochrome Display Adapter]: established by IBM as part of
the original Personal Computer [PC]. MDA is a monochrome-only, text-only
standard, allowing text display at 80x25 characters. This video display
is OBSOLETE.
CGA [Color Graphics Adapter]: The CGA standard [1981] supports
several different modes; the highest quality text mode is 80x25
characters in 16 colors. The monitors are digital with a composite signal
which is at TTL logic levels; Hs, Vs, and RGBI all at TTL logic levels.
This video display is OBSOLETE.
EGA [Enhanced Graphics
Adapter]: This EGA standard [1984] offered improved resolutions and
more colors than CGA. EGA allowed graphical output up to 16 colors
(chosen from a palette of 64) at screen resolutions of 640x350, or 80x25
text with 16 colors, all at a refresh rate of 60 Hz. The monitors have a
digital interface. This video display is OBSOLETE.
VGA [Video Graphics Array]: VGA [1987] is a
superset of EGA, incorporating all EGA modes. Older displays sent digital
signals to the monitor, while VGA (and later) send analog signals. This
change was necessary to allow for more color precision. The link provides
pinouts and signal names with a description of the bus.This video display
is OBSOLETE.
XVGA [eXtended Video Graphics Array]: 1024 x 768 resolution
SVGA [Super VGA] offers more colors and
resolutions, but really does not exist as a single standard. The primary
standard refers to the BIOS, and how the computer talks to the monitor.
VESA Display Data Channel [DDC] is a VESA standard that defines how to
read certain pins in a standard SVGA monitor to query the monitor's
capabilities. The link provides pinout and signal names with a
description of the bus.
FPDI [Flat Panel Display
Interface] describes the electrical layer, logical layer, and
connector interface between flat panel displays and display controllers
in an integrated environment. Also FPDI-1, used with VGA and SVGA [800 x
600]. Followed by FPDI-2
VMChannel [VESA
Media Channel] describes a hardware interface for desktop multimedia
systems. The VMChannel is a multiple master, multiple drop, clock
synchronous interface designed for concurrent pixel data streams.
VMChannel enables the real time flow of uncompressed multimedia pixels in
a bidirectional fashion between multiple video adapters.
Editor Comment; the release dates that accompany most of these interfaces should clearly indicate that these buses are no longer in common usage.
Although the interfaces do relate to the same time period as the XGA video interface.
In any event, the interface that defines the cable between the PC and the monitor changes about ever 5 years.
As of 2012 either DisplayPort, or HDMI would be preferred [depending on the monitor].
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