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Originally Posted by Twanger
Well, It´s not that simple. The CD-Rom is NOT controlled via the CFGIN or CFGOUT of the DMAC.
The CFGOUT is connected to the diagnostic port (my schematics say that; I know others say that the CFGOUT is NOT connected...), and the CFGIN is also connected to the diagnostic port where it is finally grounded...
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You are correct, the CFG pins are in no way used for CD-ROM control. However I didn't imply that. Actually, reading my replies, I've never even hinted that! I've been talking about autoconfigure all the time.
What I tried to say is that DMAC is there because it is the CD-ROM controller of the CDTV. (just like the DMAC in your A590 handles the Zorro <-> SCSI-chip and Zorro <-> XT-IDE-bus[*] communication.)
CFGIN and CFGOUT are used for AutoConfiguration of the devices on your Zorro bus.
The DMAC is part of the autoconfig chain inside the CDTV, so you really need to put your autoconfig devices inbetween the DMAC and where ever it's CFGOUT pin might lead in order to get Autoconfig working.
If you take CFGIN from the DMAC and put it into CFGIN of your A590, you'll end up with two Zorro II devices autoconfiguring themselves during the same turn -> conflicts and misery.
The Amiga Hardware Reference manual describes exactly how the autoconfig mechanism works, but in basic it's a chain of
motherboard -> CFGIN1
CFGOUT1 -> CFGIN2
CFGOUT2 -> CFGINX
CFGOUTX -> motherboard.
As many as you have Zorro boards (and of course making sure that they fit in the Autoconfig address space). Each autoconfig device gets to configure itself in turn and then it passes the turn over to the next one via the cfgout pin.
[*]XT-IDE is not in any way compatible with 16-bit AT-IDE drives, smoke will come out, do not attempt to connect modern drives there.