As the title says this is a modular/expandable design for a queue. A queue is a memory device where you can add things to it and removes things in the same order as they were put in, also known as a FIFO(first-in first-out). The main part is what I call the event queue. The event queue is made of up a number of modules that store 1s that build up at the end. “Events” are 2-tick pulses sent into the event queue to signal that a valid input has been entered and is ready to be stored. The event will travel down the event queue and lock the repeaters connected to the module it settles in. The first thing in the queue can be removed by sending a 2-tick pulse into the reset of the last module, removing it and causing the other words in the queue to move forward by 1 to fill the empty space. Each module can store one event and the event queue, along with the size of the individual words it stores, can be expanded indefinitely. One drawback is that the bigger it is, the slower it gets, as it takes more time for input data to reach the end