Video Graphics Array (VGA) was developed by IBM in 1987, and can only transport analog signal, it was designed to show a resolution of 640×480 with 16 colors or 320×200 with 256 colors.
XGA was developed by IBM in 1990 and supports 640×480 or 1024×768
The SVGA is a shortcut for Super VGA, and supports 800×600 or 480000 pixels, and 16 million colors, and the SVGA standard is developed by a group of manifacturers that are called VESA (Video Electronics Standards Association)
WXGA supports 1280×800 or 1280×768
SXGA support 1280×1024
VGA connectors has 15 pins:
1 = Red Video
2 = Green Video
3 = Blue Video
4 = Monitor ID 2
5 = TTL Ground (Monitor self-test)
6 = Red Analog Ground
7 = Green Analog Ground
8 = Blue Analog Ground
9 = Key (Plugged Hole)
10 = Sync Ground
11 = Monitor ID 0
12 = Monitor ID 1
12 = Monitor ID 1
13 = Horizontal Sync
14 = Vertical Sync
15 = Monitor ID 3
Some advise when using VGA:
When using VGA to connect a computer to a screen or projector it is a good advice to use quality shielded cables, if you use cables of less good quality you might experience “ghosting” which is when things starts to look like they have a shadow on the screen, the higher resolution you use the higher risk you have of “ghosting”.
You can hear more about VGA in this 5 minutes video:
HDMI also called High Definition Multimedia Interface, is use to transport digital high resolution video and multichannel audio over a single cable, it can also control TV and monitors through the cable.
HDMI is based on DVI, but HDMI can also transport audio in comparison to DVI.
It comes in different connectors:
Type A is a 19 pin connection
Type B is a 29 pin connector, which is compatible with dual link DVI
Type C is a 19 pin min connector
Copy protection also called HDCP was introduced to HDMI in year 2000, it is a two way communication with in the i2C control interface, each time a HDMI is connected, a three-part authentificaion occurs:
1. shared values, or coeds between devices
2. the KSV of each receiver is reported to the source
3. Frame-by-frame ciphers are sent to the receivers that enable data decoding
HDCP uses a hierarchy of sources, and all devices has to communicate, the hierarchy supports up to 7 levels of repeaters and up to 128 devices. When a source receives HDCP content it gets authenticated, decrypted and the re-encrypted before it gets transmitted to the next source.
CEC – Consumer Electronics Control is a plug-and-play to control devices connected via HDMI, it can be a videoconference system controlling the monitor or similar.
CEC was introduced with HDMI version 1.2a
The difference between the HDMI versions:
HDMI 1.1: support for DVD audio
up to 8 channels of 192 kHz/24 bit audio (PCM)
HDMI 1.2: support for 1-bit audio
HDMI type a connectors
HDMI version 1.2a CEC
HDMI 1.3: bandwidth up to 340 MHz which gives higher resolution and deeper color.
HDMI 1.4: HDMI ethernet channel (can send and receive 100 Mb7sec ethernet)
Audio return channel
3D is supported with 3D in dual-stream 1080p
Expanded support for color spaces
Type D micro connector
HDMI 2.0: Also called HDMI UHD
4:2:0 chroma sampling
up to 32 channels of audio
Additional CEC functions