Where to find a boolean source for D flip-flop?

Hi all!

I want to simulate a SIPO register using D-type flip-flop in Simulink.I want to give the flip-flip 8 bits( for example 00110011) as inputs just once and these will be output in paralel. However, where to find a Boolean-typy signal source as the D-type flip-flop's input in Simulink? Best regards