Is there a limit on # of ATA busses?

[jruschme]

I have a dual 1.0 MDD. Until recently, I was running a drive with Leopard (SATA with ATA bridge) ont the fast bus and an older ATA drive with Tiger on the slower bus.

I recently installed a generic Sil3112 "1+1" card that I had flashed with Mac firmware from Weibe and moved the Leopard drive over to it. Everything seems to work fine with one exception:

If I boot the Tiger drive, I can see the Leopard drive on the desktop. If I boot from the Leopard drive on the SATA controller, however, the OS boots fine but the Tiger drive is nowhere to be found. According to the 10.5 system System Profiler, the Sata card is actually an ATA bus, only three are visible, and the Tiger drive is not seen.

Thoughts? It seems like something is limited to three ATA busses and the SATA card ends up overriding one of them.