# Sequential Logic

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Sequential circuit [1]

A Sequential Logic is a digital circuit where one or more outputs are boolean functions of multiple inputs and the history of the outputs. In contrast to combinatorial logic, a sequential logic requires memory to somehow feed the history of the outputs back to the inputs. Usually, for deterministic and reliable behavior considering internal latencies and propagation delays, a sequential logic is synchronous, that is the memory only change their content on the edge of a clock signal.

# Applications

Sequential logic, that is combinatorial logic combined with memory, is the base of Finite-state machines, Turing machines as well as digital computers.

# Sequential Rook Attack

As an further example, a sequential logic may perform the same task as mentioned in Combinatorial Attack and Defend Map, but with less gates in up to seven cycles - similar to the bitboard techniques like Dumb7Fill:

```                                             +-------+
+------+     |       |
o--/64/-- empty(square) -/64/--| 64:1 |---->|       |-----o result reliable / otherwise processing after reset
+------+     | Comb. |-----o A8 is attacked by white rook from south
^         | Logic |
+------+     |       |
o--/64/-- wrook(square) -/64/--| 64:1 |---->|       |-->--+
+-----.+     |       |     |
^      o->|       |     |
/6|      |  +-------+     |
|      |                v
+--------------+           |
|              |           |
|    Latch     |<----------+
reset o----|              |
+---^----------+
|
clk
```