Can a PCI device communicate with another device attached to the bus system?

[bhagatindia]

Hello,

Can a PCI device(say a card with general purpose CPU) communicate with another device(lets say a NIC or hard disk) directly without CPU intervention?

Thanks,
Srinivas

[tthtlc]

All devices usually have some DMA capabilities. So after configuration stage, they will be able to write directly to the phyical memory. But two devices will be setup to access different parts of the physical memory - so who is going to copy the data from one part of the physical memory to another? This third party is the CPU.