Finally, after a few months waiting, Elbox released their Mediator 4000 "core logic" card. I ordered mine and it arrived the next day, so I opened up my machine and figured out how to install it.
My package came with the Medaitor 4000 itself, the MultiMedia CD which has drivers for TV cards, sound cards and 100Mb ethernet cards, and a replacement busboard for my A4000 tower. The new busboard has both seven Zorro II/III slots and five PCI slots, as well as a single video slot. One of the Zorro III slots is used by the Mediator, which also connects to a special PCI slot, although there are actually still five usable PCI slots in total. This is one more than the A1200 version of the Mediator, which is a little frustrating for some A1200 owners who have already got hold of a graphics card, TV card, sound card and ethernet card, and so now have no free slots.
The Mediator has three jumpers on it. One is for setting the PCI memory window size, which can be either 256MB or 512MB. Unless you have a Voodoo 4 or 5, 256MB is the recommended setting. The second jumper is for controlling the order in which the Mediator configures itself at boot time. You only need to change this if you have a Zorro III graphics card, which I do. The final jumper is for use with the Shark G4 board that Elbox are set to release.
If you look closely at the picture PCI/Zorro busboard, you can see that it has a power connector labeled "P9". Presumably this was included to provide another power source for the busboard, so as not to overload the power lines from the A4000 motherboard connector. It's probably a good idea too, since you could in theory run up to 12 cards at once. However, since my tower is an RBM Digitaltechnik TowerHawk it uses an ATX PSU, and the P9 connector is from an old AT style supply. Luckily, I had an old AT supply handy to raid for parts, and found the pin outs for P9 in the Hardware Book Online. P9 carries three voltages: +5V, GND and -5V. Fortunately, I noticed that the -5V line is not connected to anything on the busboard, so I only needed to supply the other two voltages which I took from one of the standard 5.25" power connectors in my tower. I quickly made up an adaptor cable:
I removed all my Zorro cards from my computer, and took my old 7 slot Zorro busboard out. The new PCI busboard fitted nicely, although the mounting screw holes did not line up correctly so I had to carefully support it with cable ties. It's fairly solid now.
As I had feared, the holes at the back of my tower did not align with the slots on the new busboard correctly. They were about 1cm out, but I had already planned for this and knew what I had to do. The rear part of the tower is made of two metal sections, and unfortunatly it was impossible to move the slot holes or adjust them easily, so I simply removed the offending metal crossbeams. I did this with my trusty Dremel-clone, and it generally worked out quite well. I can still support the cards with screws, and the lack of crossbeams is no worse than most other towers.
After powering up with just the busboard in place, I checked that the power connector was okay and nothing was getting hot. As nothing was wrong, I installed a Zorro card and tried that. Still all okay so I put in my PicassoIV and made sure I had a picture from it. Finally, I fitted the rest of the Zorro cards back in and attached the Mediator. An early startup screen revealed a long list of expansion cards, and listexp from the Identify.library package showed up two new Elbox cards. "Two?" you ask? Well, the Mediator configs twice, once for PCI memory space and once for it's own control register space.
Finally, I tried out a PCI 10Mb ethernet card. I had it working in moments, and could ping all the other computers on my home network. I am now waiting for a Voodoo 3, at which point I will update this site again.