NightShadowPT wrote on 2023-07-29, 10:42:

Hi, […]
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Hi,

As have recently opened yet again my Compaq Deskpro M for troubleshooting other issues, and I have noticed that my graphics card has an expansion connector at the top, and would like ask if anyone knows what it's for.

The card is an EISA Compaq QVision 1280/E, part number 139183-001.

I am attaching a photo so you can all see the connector I am talking about (top of the card) - 25/26 pin connector

Thank in advance.

VESA connector

(Better plug "VESA feature connector" into the search engine of your choice instead when doing further research, to avoid all the VESA mounting hardware)

It's meant to connect other video devices to the graphics card for control/video pass-through. I used that connector with a dedicated TV card in the mid-90s.

Dedicated MPEG decoders often used that connector as well.

Hey, look at this: all 8 pixel data bits, the video clock, HSYNC and VSYNC! This is all dynamic data you need to create a digital (HDMI/DVI) output from that card. You also need to know the contents of the VGA palette registers, which likely can be snooped from the ISA bus like any motion video picture-in-picture board did at that time. Did anyone build a digital output option like this yet?

mkarcher wrote on 2023-07-29, 15:05:

Hey, look at this: all 8 pixel data bits, the video clock, HSYNC and VSYNC! This is all dynamic data you need to create a digital (HDMI/DVI) output from that card. You also need to know the contents of the VGA palette registers, which likely can be snooped from the ISA bus like any motion video picture-in-picture board did at that time. Did anyone build a digital output option like this yet?

Yes. Search this very forum for "crt terminator"

I just watched the YouTube video on the CRT Terminator. That's pretty neat. I like that the creator claims it would work for VLB-based graphics cards as well as ISA.

I wish I had better soldering skills because 200€ before shipping is a bit steep. I can't blame the creator for wanting to make money off the creation, but I can do a lot of other retro (and modern) stuff for that kind of money.

PC Hoarder Patrol wrote on 2023-07-29, 11:13:

VESA connector

CPQ 1280E VESA.jpg

Thanks for the quick answer!

Also, cool to see it directly from the manual 😀

Had no idea these cards had this kind of interface... I don't think I'll have a use for it, but cool to know anyway.

Cheers!