The SRP card is a 2-port intelligent (with its own 8-bit CPU) synchronous serial card with V.24 interfaces up to 80kb/s each.

The COSA is a next-generation sync/async board with two interfaces - currently any of V.24, X.21, V.35 and V.36 can be selected. It has a 16-bit SAB80166 CPU and can do up to 10 Mb/s per channel. The 8-channels version is in development.

Both types have downloadable firmware and communicate via ISA DMA. COSA can also be a bus-mastering device.

Each device needs one IRQ line (sharable by both channels), a DMA channel and two I/O ports (16-bit COSA requires three I/O ports). The I/O ports, DMA channel and the IRQ line can be set using jumpers (set-and-work, as opposed to plug-and-play).

The hardware is fully documented, so you can build your own COSA card, if you want.