FAST Pinball hardware kits consist of a controller board (which has the USB connection to your computer) plus one or more “I/O boards” which have connectors for switches and drivers. (Different models of I/O boards have different numbers of each).
The FAST Pinball controller and all the I/O boards are connected in a “ring” network which we call the “FAST Loop Network.” (This network uses RJ-45 style CAT-5 cables to connect, but it’s not Ethernet or TCP/IP, rather, it’s a dedicated network which delivers communication data and power to all the boards).
Having distributed I/O boards means that instead of having one huge driver board in the backbox like ‘90s machines, you put multiple smaller boards throughout your machine, drastically saving on wiring and simplifying troubleshooting (since each I/O board is only connected to drivers and switches via shorter wires in its own “neighborhood”). You literally don’t need to buy a hundred different combinations of multi-colored wire since you don’t have massive spinal cords of wires connecting your playfield to your backbox!
The other major advantage of the distributed I/O boards connected via the FAST Loop Network is that each I/O board has its own processor. (Literally there is a CPU on each board!) This means that the “burden” of firing drivers based on switch events, watching switches for state changes, and doing all that math and time tracking to make sure switches are debounced is handled locally on each I/O board.
So no matter how many drivers or switches you add to your machine, the “burden” on the FAST controller and the “burden” on the FAST Loop Network is not increased. Literally every additional I/O board you drop in is adding another processor to the system to help take on the load.
The only data that flows through the FAST Loop Network is the configuration of the drivers and switches as well as the switch events which are reported to the computer. (Well, and some other technical things, like watchdogs and system status messages, but you get the point. Adding more I/O boards to a FAST Pinball system does not increase the load on the network or the load on the main controller or the load on the host computer.)
FAST Pinball control systems are modern parallel computing at its best. Additional I/O boards add capability, not burden. And latency of driver response is not tied to the shared communication between the various boards.