Compared to Version 1, Version 2 ATM NIC has PCI bus interface, instead of the ISA Bus interface. Since the ISA Bus speed is much slower than the ATM transfer rate, the throughput of our version 1 ATM NIC card is nowhere near the NIC speed (100Mbps). PC manufacturers also think that the performance of the ISA Bus is not adequate as more and more interface cards are equipped. In 6/22/92, Intel released the PCI Version 1.0 specification to replace the traditional ISA Bus. Now, in most PC, you can find the new generation bus-PCI inside.
According to the above reasons, we decided to use the PCI Bus as the interface between our card and the PC host. Because the PCI Bus is a new bus technology to us, we changed our ATM NIC card architecture in two steps.
Step 1: Because we didn't know the PCI Bus very well, we used the AMCC S5933
PCI controller to implement our ATM NIC card.
Step 2: From the experiences of implementing Ver 2.0 card and further study about the
PCI technology, we designed the PCI controller by ourselves to replace
the AMCC S5933.