# Team:Melbourne/Overview

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We want to build a biological clock that can count up when it is "ticked" by input light pulse signals. As the signal "ticks" the clock, the clock changes color and observer can use the **color** or **combination of colors** to tell what "time" it is.

There are two types of clocks proposed by our team.

The first type is a **Binary Clock**. In the Binary Clock, there are identical units (in fact not totally identical but almost) which are connected in series to make the entire clock. We call each unit a **bit-unit**. Each bit-unit can be turned on and off by its input signal and give its output as the input signal for the next bit in the series. So for example Bit1 can have 2 states ON or OFF, Bit1's output is the input for Bit2 to turn Bit2 ON and OFF. So with 2 bit-units, there are totally for states and these 4 states happen in a sequential order 00 -> 01 -> 02 -> 03, because Bit2's input is Bit1's output. If we extend to 3 bit-units, the number of possible states will grow *exponentially* to 8.

Each bit-unit is said to be **modular** because, apart from input receptor and output molecule, the ** internal machinery** are identical.

We also proposed a ** Linear Clock**. The linear model is similar to and simpler than the Binary model. The difference is that each bit-unit is turned ON only once and once it is turned OFF by the next bit-unit, it will stay OFF forever. So you can imagine this system as a string of light globes, the light jumps from one globe to the next and people can read the time by just looking at which globe is on. This model is also ** highly modular** and the internal machinery is considerably less complex than the binary system.

The ultimate goal of these systems is to construct a biological production pipeline of which the systems can keep track on what stage it is and decide what reagents to release for the next step.