Begin filling up the black box file

docs/Black_Box_Analysis.md

@@ -13,10 +13,17 @@ Even when the chip lock is set (thus blocking direct reading via a programmer),
 Things get a bit harder when we consider registered PALs: these ICs add an array of flip-flops to the network.
 These flip-flops have one of their outputs connected to a pin and another feeding back into the network of wires. A **clock** pin is also added to the IC so that the flip-flops can be toggled.
 
-This boils down to the fact that, when toggling the clock, the new value of the outputs connected to the flip-flops is no longer dependant on the inputs alone, but also on the feedback lines coming from the flip-flops themselves, i.e. when the clock is toggled, the PAL changes its internal state, and the new state is dependant on the previous one.
+This boils down to the fact that, when toggling the clock, the new value of the outputs connected to the flip-flops is no longer dependant on the inputs alone, but also on the feedback lines coming from the flip-flops themselves, i.e. when the clock is pulsed, the PAL changes its internal state, and the new state is dependant on the previous one.
 
 ## Analyzing a registered PAL device
 
 ### The Not-So-Black Box
 
 As I hited at in the introduction, a registered PAL device can be viewed as a stateful system, whose current state is dependant on the previous one plus the state of the inputs at the time of moving to the new state.
+
+Luckily for us, the number of the possible states is known and dependant on the number of flip-flops in the device (and, as every flip-flop is connected to a specific output, dependant on the number of so called **registered outputs**). Having said flip-flops directly connected to outputs gives us an important insight on the PAL, as *we know exactly in which state it is at the moment*.
+
+To summarize and simplify, a registered PAL has the following types of outputs:
+
+- **Combinatorial outputs**: their state is dependant on the current state of the inputs and on the current state of the registered output feedbacks.
+- **Registered outputs**: these only change when the clock pin is pulsed, and their new state depends on the state of the inputs and on their own state before the pulsing.