PCI graphics cards with PassThru

[alexh]

A long time ago when PCI graphics cards were the norm, some (all?) of them had an internal passthru connector on them.

This internal connector could be used with MPEG decoder cards and Voodoo 1 & 2 cards etc. to connect them internally and avoid using the loopback cables.

Do any popular Amiga enabled PCI gfx cards still have these interfaces? (They looked a little like a clock port header)

I've not looked for a long time, but if any of them do, it would be easy to make a cheap Automon.

[alexh]

There are for at least 1... my VIRGE DX card has one.

[alexh]

keropi wrote:
The PCI voodoo3 3000 has one, 26pins in 2 rows.

Oooh, I'll ask about (and everyone here do the same) and lets see if we can get details about the connector and its signals.

It should be EASY to convert one of these cards + internal scandoubler into a CHEAP, quality, Automon solution.

the pci busboards should offer by default a built-in switcher like the picassoII...

And how do you suggest they do that?

They would have had to include a cable which clipped over the AGA chip, probably a scandoubler too, it would have doubled the price of the PCI adapter dont you think?

[alexh]

I think I've found it...

http://www.epanorama.net/documents/pc/vga_feature.html

It is not what I thought it was and possibly useless

I could have sworn that you could CHROMA-KEY data IN through this port, but it appears it is nothing more than a glorified internal VGA connector.

[alexh]

If it can be made to an input I thought it used a form of chroma-key.. If the screen is all MAGENTA it replaced these pixels with pixels from input.

If it CAN be made an input... maybe AGA in a window would be possible... but I am stretching a bit far on this one without finding out if it can be an input.

I thought that MPEG cards and TV cards etc. came INTO the VGA cards... but perhaps it was the otherway around.

If it was bidirectional then YES!!

http://en.wikipedia.org/wiki/Feature_connector

[alexh]

I will ask around and have some talks with other Amiga hardware designers. I'll concentrate on the connectors on the Virge and Voodoo3 (hopefully the same) and see if it has any use.

[alexh]

Alex, are we talking about the connector at the top, in the middle, of the card?

Yes.

you can get the signal at the entrance of the VP101

Heh, I worked on the team that designed that Chip :-) I've got a box of 1000's of them and the Tapes of the design. And probably the load testboards.

I'd probably get the signals directly from either the Lisa chip, just as modern internal scandoublers do.

OR

From the Scandoubler's FPGA/CPLD before it's DAC.

[alexh]

At the moment I cannot find enough RELIABLE information on the VGA Feature connector, specifically the one on the Voodoo3.

At the moment I am assuming that this is just an output so of no use to us.

I am also assuming that it is 8-bit non-paletted colour too so the colour / picture quality wouldnt be very good.

If it turns out to be bidirectional, and enhanced to more than 8-bits then we would be in buisness.

[alexh]

Digital Video INPUT sure as hell makes it sound more useful.

[alexh]

But the pinout doesnt match the VGA Function Connector... which means either this document is wrong or it is a custom connector and that means even MORE work to discover its secrets

It's input is REC601 digital video which is not exactly what the Amiga outputs.

There is an I2C interface on there probably to allow you to program the RAMDAC externally.

Working out how this works is going to be a nightmare... we need someone who used to work at 3DFX.

[alexh]

Worst case: Automon... automatic switching between gfx cards and amiga native.

Best case: Native Amiga display in a window in RTG mode.

However it is looking less like the Voodoo3 has a VGA Feature connector and some strange 601 video connector. Good for MPEG, not very useful for Amiga's.

[alexh]

Unfortunately the video input has to be in REC601 format (Y'CbCr) sometimes known as YUV.

Normal Amiga output is of course RGB.

There is a SLIM chance that the VP101 video encoder, used to generate composite, has it's REC 601 outputs enabled.

If it does, it should be possible to create a clip which clips over the VP101 and connects to the Voodoo feature connector and allows you to display Amiga native screens both in a window and full screen.

Some more research required, and as I dont have either an A1200 or a PCI board, or a Voodoo 3 I dont think I will do anymore.

It is VERY possible that with only a small investment of time you could make a DIRT cheap, medium quality (some data loss through 2x colour space conversions), scandoubler which may have the extra cool ability to be displayed in an RTG window.

[alexh]

The VP101 is not the chip I remember.

It was designed by our team but long before I got there. It is not a true video encoder and doesnt have REC601 outputs, just analog RGB and Composite. The signals are probably there internally but not pinned out.

This means you'd have to have a small CPLD/FPGA to do the RGB to Y'CbCr colorspace conversion. Easy to do and I could provide VHDL for anyone interested :-)

[alexh]

@MASACREWILL

Thanks but all the information (about the electrical and timing) of the interface was provided on the previous link.

Programming the 3dfx chip for this mode and whether or not the interface automatically scandoubles is not known at this time.

------------------------------------------------------------

@Motorolin

I am not 100% interested in this area. I have possibly the four best Zorro cards: XSURF, Picasso IV, Fastlane and DKB3128 I am not really interested in PCI.

I noticed that these boards had this interface.

I noticed that lack of Automons / Scandoublers is always a sore point.

I had hoped it would be a simple "wire up n go" but as we have discovered it is not.

The only interest now is to trying to stimulate the likes of Individual Computing or perhaps someone who has a PCI setup into developing the idea further.