China DOS Union

Can all ISA sound cards produce sound under DOS?

I want to buy an ISA sound card to play music under DOS. Creative ones are too expensive, so I want to buy something else (such as YAMAHA-719), so I'm asking first...

You could say that; at least the vast majority of ISA sound cards are like that.

As far as I know, ISA sound cards can all produce sound under DOS, as long as you have installed the driver correctly.

As long as the driver is installed properly, PCI sound cards can also be used under DOS. My Hua Wang YMF724 sound card can be used under DOS.

There are various ways to use PCI sound cards under DOS, such as installing drivers, SB-Link technology, emulation technology, and so on; the most common is the first one. Or they can also be used in a Win9x DOS window.

Can an onboard ac97 sound card on the motherboard work normally under dos?

Is there a universal isa driver?
My Creative SOUND BLASTER16 has no DOS driver and has been sitting idle all this time.

There is no universal driver. Drivers for Creative Sound Blaster cards should be fairly easy to find. But putting one in a P3 or P4 computer is basically slowing the machine down, and besides, it may not even have an ISA slot.