I'm trying to test an old PC which controls a ABB Bomem FTIR Spectrometer (DA&). The internal PC for this instrument is an American Megatrends, Inc. Super Voyager VLB-III ISA Motherboard


I want to connect a monitor, the manual states:

“a special 10-pin header can be connected to the feature connector of a standard VGA Controller card. A signal from this header drives HSYNC, VSYNC, and Enable Video Low during Sleep Mode. If a Green PC monitor is used, the monitor switches to its own low power mode during Sleep Mode.”

So it sounds like it needs a ISA VGA card like https://www.artisantg.com/TestMeasurement/62768-1/Western-Digital-VGA-8-ISA-Card

The manual then states:

"J47 Green PC Monitor Connector Attach a 10-wire 10 to 26-pin flat cable between J47 on the motherboard and the VGA Feature Connector on the VGA adapter card or Graphics Accelerator. J47 is shown below. The VGA cable is pictured below. After the timeout period specified in Power Management Setup expires, the motherboard drives the SYNC ENABLE, HSYNC, and VSYNC signals Low through open collector outputs. Monitors that support the Display Power Management Specification (DPMS) can turn power off after examining this condition, saving power."

I haven't been able to find the pinout or any 10 pin --> 26 pin flat ribbon cables. Does anyone know what the pinout is for those cables? Can anyone tell what VGA controller card would be compatible with this motherboard (8 vs 16 bit? etc).

thanks oman

  • well, you really want a VLB card, or video is going to be slow, even by the standards of the time. Are you trying to repair the spectrometer ? If so I'd want as similar card as original as possible, as who knows what the software does. An 8bit ISA will work, but will be truly horrendous for anything graphical
    – camelccc
    Apr 19, 2023 at 17:40
  • Hi thanks, i simply want to see if the computer is still working. So seeing if it will post would be enough. So i'd be happy just to get to the bios or command line. But i gather a 16 bit card would be better and you see no reason it wouldn't work?. Any idea on the cable required between the motherboard in graphics card?
    – oman
    Apr 19, 2023 at 19:33
  • Is this cable even necessary? The motherboard manuals makes it sound like it is but perhaps that's only related to using a "Green PC Monitor". This discussion , forum.vcfed.org/index.php?threads/vga-feature-connector.42898 , makes it sound like the "feature connector" is only for external cards using the graphics card memory or something similar.
    – oman
    Apr 19, 2023 at 19:40
  • most certainly isnt necessary. Neither would it be useful running any os that supports dpms, eg windows.
    – camelccc
    Apr 19, 2023 at 19:46

1 Answer 1


Page 54 of the motherboard manual gives the pinout of its custom 10-pin connector as follows:

Pin Signal Pin Signal 1 N/C 2 N/C 3 N/C 4 N/C 5 TTL output for SYNC enable 6 Open Collector output for HSYNC control 7 N/C 8 Open Collector output for VSYNC control 9 N/C 10 GND

Details on the VGA Feature connector are hard to find. My copy of Upgrading and Repairing PCs (10th anniversary edition) from 1998 describes it as poorly used, partially because it was poorly documented by IBM in the first place, and doesn't actually give a pinout for it. I have, however, found an archived copy of an email from 1993 online that gives the required details:

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

A similar pinout for ATI graphics cards in the same email matches the above information.

On that basis, it appears that you need four connecting wires, as follows:

Motherboard VGA Card Pin 5 - TTL sync enable Back pin 5 - Select internal sync Pin 6 - HSYNC output Front pin 11 - External HSYNC Pin 8 - VSYNC output Front pin 12 - External VSYNC Pin 10 - Ground Back pin 1-3 or 8-11 - Ground

Note that this cable allows your motherboard to override the VGA card's sync signals, and thus power off the monitor when the machine is idle. It isn't required for normal functionality of the graphics card.

As such, your machine should support any standard 8-bit or 16-bit ISA graphics card (though you presumably want to stick to VGA, and avoid older EGA/CGA standards unless you have a compatible monitor). The very best cards your board supports would be one that uses the VESA Local Bus (VL-Bus) slots, which were designed to allow fast direct memory access for video cards in the pre-PCI bus days. These will be rarer than regular ISA VGA cards, however.

  • thanks very much for the extremely detailed answer. i've ordered a Trident TVGA 9000C and hope i'll just be able to slot the card in and get something on the old VGA monitors I have. I think i was just confused by the manual which make it sound like you have to have this cable connected. But i think that was in relation to this Motherboard mainly being a Point Of Sale (POS) PC which often used these "green monitors" which would power off to save power. Hopefully the information you provided helps our some future internet surfer :)
    – oman
    Apr 24, 2023 at 16:57
  • You're very welcome. If you feel this answers your question, feel free to give it a green tick to accept this answer, and mark the question as 'answered'.
    – Kaz
    Apr 25, 2023 at 17:45

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