Velleman usb experiment interface board velleman k8055n the velleman usb experiment interface board kit has 5 digital input channels and 8 digital output channels plus two analogue inputs and two analogue outputs with 8 bit resolution the number of inputs outputs can be further expanded by connecting up to 4 more cards to the pc s usb connectors all communication routines are contained in a dynamic link library dll you may write custom windows xp vista windows7 applications in delph