For the first question, you are basically passing the video signal through to the Voodoo2 and using the DB-15 connection of that card for output (and degrading the signal quality by doing so). Was the connection loose or anything on the Trio card? For the CF card issue, have you tried running FDISK /MBR ?

For CF card - you have to make 1st partition active - use FDISK utility.

The same card has been working absolutely fine on my socket 7 board, with or without the Voodoo. The cable was fine at both ends. It's obviously not a processing issue because the 3DFX hardware isn't being utilised in DOS but, if it's a cable issue, it should persist because the loop through cable uses the same socket on the 2D card, passes it through, and sends it to the output cable. It makes no logical sense really, so I wondered if anyone else had come across a similar thing.

The second point - now I think about it, it's quite possible that, because I let the setup program prepare the disk, that the partition either isn't primary or active so I guess I'll go back to basics and try again. Thanks.

If the CF card is bigger than 504 MBytes (and your 486 has an old BIOS) you might have to use a Dynamic Drive Overlay software. Back in 1996 a friend of mine had success using a 2 GB HDD in his 486 (DX2/80) by turning of the 32-bit handling of IDE drives. I wasn't lucky with our 486 back then, I had to use Dynamic Drive Overlay software on my 486, when installing a 1 GB HDD. A similar issue with my 286 +booting from CF was resolved using DDO software.

kixs wrote:

For CF card - you have to make 1st partition active - use FDISK utility.

Weird. I checked FDISK and it said the partition was primary and already active. Deleted it and recreated it anyway (I should know better than letting software do something for me), reinstalled DOS and of course it worked.

I have removed the 3DFX card and the S3 is working perfectly fine now, of course. It could only have been a cable issue given the symptoms. Silly.

If the CF card is bigger than 504 MBytes (and your 486 has an old BIOS) you might have to use a Dynamic Drive Overlay software.

Fortunately it's only 256MB - thought I'd go with something era-correct 😊

You can also use bigger CF cards - I use 8GB one, but only created 500MB partition. I use generic BIOS settings: C:1024, H:16, S:63 and it always works - from 286 to Pentiums.