I've got a dual 1.42GHz powermac and a PCMCIA soundcard. There appear to be millions of card for PC's that are a PCI card with a PCMCIA adapter on but can you get them fro the G4?
What is the reason for the sound card? Try to see the card if it works.
Apple has had the sound issue bang on for year using their iSub and Soundsticks technology that plugs into the earphone port. Not sure what you are trying to do but trying to use the PC analogy in a Mac is not necessary.
PC's are stripped down boxes and you added functionality. Macs were the reverse - they had an all in one solution that worked and then you added to enhance the solution.
Does the pcmcia card have mac drivers? If it doesn't it's not going to work in the Mac period, unless you can find drivers for it, or coax another manufacturer's driver into working.
To answer your question: I have not seen a PCI -> PCMCIA adapter that's specifically labeled as mac-compatible. However, there are a number of PC devices which will work in a Mac, even if it doesn't say they will. For the price of a PCI -> PCMCIA adapter card on eBay, you might as well just pick one up and try it. It's not going to damage the Mac, unless there's a manufacturing defect in the card (in which case it'd damage any system you put it in).
PC's are stripped down boxes and you added functionality. Macs were the reverse - they had an all in one solution that worked and then you added to enhance the solution.
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