VGA feature connector
VGA feature connector is a 8-bit expansion bus for VGA card standardized by VESA. That conenctor has been very popular for many years, but because it's limitations (not enough bandwidth for high resolutions and only 2560 color mode support) it is going to be replaces with something else. Some manufacturers (for example AT) have shifted to VESA Advanced Feature Connector.
From: [email protected] (Dominic H Goode) Newsgroups: comp.sys.ibm.pc.hardware,comp.sys.ibmpc.misc,sci.electronics Subject: VGA Feature Connector Date: 12 Apr 93 22:59:42 GMT Organization: Brunel University, Uxbridge, UK X-Newsreader: TIN [version 1.1 PL8]Does anyone know how the VGA video feature connector operates? I would like to know which of the pins are inputs, which are outputs, and which are bidirectional (if any - and how the direction is selected).I have found a pinout for the connector:
Video Feature Connector Pinouts
Pin Name Function 1 PD0 Dac Pixel data bit 0 2 PD1 bit 1 3 PD2 bit 2 4 PD3 3 5 PD4 4 6 PD5 5 7 PD6 6 8 PD7 7 9 - Dac Clock 10 - Dac Blanking 11 - Horizontal Sync 12 - Vertical Sync 13 - Ground 14 - Ground 15 - Ground 16 - Ground 17 - Select Internal Video 18 - Select Internal Sync 19 - Select Internal Dot Clock 20 - Not Used 21 - Ground 22 - Ground 23 - Ground 24 - Ground 25 - Not Used 26 - Not UsedAnd I assume that pins 1 - 12 are outputs, and 17 - 19 are inputs. Is this correct?
The reason is this - I have a Rombo Media Pro+ video digitising card. It chroma keys its output into the vga monitor signal. However, although it is supposed to work with an ET-4000 with Hi-colour RAMDAC, the colours on screen behave as if the top 2 bits of colour information are missing, and red, green, blue signals are swapped around. Rombo has suggested that this may be due to insufficient buffering on the feature connector outputs, and is happy to sell me a buffer device for 50 pounds. I would rather save about 45 pounds, and build my own. I assume it would require (for example) a 74F244 buffer IC (or two).
Can anyone help? Any information on the feature connector would be highly appreciated!
Please could you reply by email : [email protected]
VGA feature connector
component side pin function 1 PD0 (DAC pixel data bit 0) 2 PD1 (DAC pixel data bit 1) 3 PD2 (DAC pixel data bit 2) 4 PD3 (DAC pixel data bit 3) 5 PD4 (DAC pixel data bit 4) 6 PD5 (DAC pixel data bit 5) 7 PD6 (DAC pixel data bit 6) 8 PD7 (DAC pixel data bit 7) 9 DAC clock 10 DAC blanking 11 Ext. horizontal sync 12 Ext. vertical sync 13 Ground back side pin function 1 Ground 2 Ground 3 Ground 4 Select Internal Video 5 Select Internal Syncs 6 Select Internal DAC 8..11 Ground
AMC
ATI has used a connector called AMC in some of their cards. It seems that the AMC is just an "extended normal VGA feature connector", as far as the pinout is concerned.
ATI Technical Support feature connector info: The 26 pin BERG connector on ATI products is KEYED with pin Z13 missing and should be labelled as follows:
------------------------------------------------------------ -----
Y1 J2 Y13
+---------------------------------------+
| . . . . . . . . . . . . . |
| . . . . . . . . . . . . |
+---------------------------------------+
Z1 Z13 (pin missing)
---------------------------------------------------------------------
IBM defines the feature connector in the following manner:
Pin Name Description Y1 C0 Colour BIT 0: an output when 'Select Internal Video' is hi. Y2 C1 Colour BIT 1: an output when 'Select Internal Video' is hi. Y3 C2 Colour BIT 2: an output when 'Select Internal Video' is hi. Y4 C3 Colour BIT 3: an output when 'Select Internal Video' is hi. Y5 C4 Colour BIT 4: an output when 'Select Internal Video' is hi. Y6 C5 Colour BIT 5: an output when 'Select Internal Video' is hi. Y7 C6 Colour BIT 6: an output when 'Select Internal Video' is hi. Y8 C7 Colour BIT 7: an output when 'Select Internal Video' is hi. Y9 DAC Clock Video clock for adapter palette/DAC. Output when 'Select Internal DAC Clock' is high. Y10 DAC Blanking Blanking Signal for adapter palette/DAC. Output when 'Select Internal Syncs' is high. Y11 Ext. H Sync Output when 'Select Internal Syncs' is high. Y12 Ext. V Sync Output when 'Select Internal Syncs' is high. Y13, Z1, Z2, Z3, Z8, Z9, Z10 & Z11 Ground Z4 Select Internal Defines colour pins (C7 to C0) as outputs when high. (Video) The adapter pulls this signal to +5 volts through a 4.7K ohm resistor. Z5 Defines SYNCS and blanking pins as outputs. The adapter uses 4.7K ohm pull-up resistor. Z6 Defines the DAC Clock pin as an output. Z7, Z12 & Z13 Not usedATI card connector pinouts are from Tan Irwin at ATI Technical Support.