Summary of Sequential Systems
QUESTION: SUMMARY OF THE SEQUENTIAL SYSTEMS
A Sequential System is a system that has memory. The output in a sequential system does not only depend on the current output, but also depends on the history of previous inputs. We dwell mostly on clocked/synchronous systems. A clock a signal that alternates between 1 and 0 at a regular rate over time. Due to the fact that the system can only store a finite number of states, sequential systems are sometimes called finite state machines (FSMs). A sequential system consists a set of memory devices and combination logic. Here, we focus on sequential systems with latches and flip flops.
Definitions of Terms
State: This is what is stored in the memory. It’s stored in binary devices but is not always naturally binary.
State Table: Shows combinations for inputs in each state, outputs and the next state i.e. what is to be stored after the next clock.
State Diagram/Graph: This is a graphical representation of a state table.
Latches and Flip Flops
A latch is a binary storage device with 2 or more logical gates with feedback depending on the gates.
We can write the equation for this system as:
P = (S + Q)’
Q = (R + P)’
The latch can either store a 0 (Q=0 and P=1) or 1 (Q=1 and P=0). S stands for Set and R stands for Reset. If S=1 & R=0, then P=0 & Q=1 and vice versa.
A flip flop is a clocked binary storage device, i.e. a storage device that stores either a 1 or a 0. The value only changes with clock transition. When the clock moves from 1 to 0, it is trailing-edge triggered. When it moves from 0 to 1, it is leading-edge triggered. Whatever is stored depends on the flip flop data inputs.
Flip flops have 1 or 2 outputs, i.e. if there is one output, it is the state of the flip flop and if there are two, the state and its compliment. We concentrate on two types of flip flops, the D and the JK flip flop.
The D is the simplest. It is the Delay flip flop since the output is just the input delayed until the next
A Sequential System is a system that has memory. The output in a sequential system does not only depend on the current output, but also depends on the history of previous inputs. We dwell mostly on clocked/synchronous systems. A clock a signal that alternates between 1 and 0 at a regular rate over time. Due to the fact that the system can only store a finite number of states, sequential systems are sometimes called finite state machines (FSMs). A sequential system consists a set of memory devices and combination logic. Here, we focus on sequential systems with latches and flip flops.
Definitions of Terms
State: This is what is stored in the memory. It’s stored in binary devices but is not always naturally binary.
State Table: Shows combinations for inputs in each state, outputs and the next state i.e. what is to be stored after the next clock.
State Diagram/Graph: This is a graphical representation of a state table.
Latches and Flip Flops
A latch is a binary storage device with 2 or more logical gates with feedback depending on the gates.
We can write the equation for this system as:
P = (S + Q)’
Q = (R + P)’
The latch can either store a 0 (Q=0 and P=1) or 1 (Q=1 and P=0). S stands for Set and R stands for Reset. If S=1 & R=0, then P=0 & Q=1 and vice versa.
A flip flop is a clocked binary storage device, i.e. a storage device that stores either a 1 or a 0. The value only changes with clock transition. When the clock moves from 1 to 0, it is trailing-edge triggered. When it moves from 0 to 1, it is leading-edge triggered. Whatever is stored depends on the flip flop data inputs.
Flip flops have 1 or 2 outputs, i.e. if there is one output, it is the state of the flip flop and if there are two, the state and its compliment. We concentrate on two types of flip flops, the D and the JK flip flop.
The D is the simplest. It is the Delay flip flop since the output is just the input delayed until the next