COSA Examples

Control-Alt-Del Component
Sequence Component
Keys-down Component
Trigger Component
Design Note
Quick Sort Component

Abstract: This page contain examples of COSA components. I will try to add as many components as I can find time to draw. A quick refresher. Small blue rectangles are female connectors. Red rectangles are male. Components and cells are shown as circles of various colors. All components are pale green. A small blue circle attached to a cell represents an input synapse. A small red circle is an output synapse. Signals always move from the output synapse (red) of one to the input synapse of another. A dotted rectangle surrounding several connectors means that the connectors together comprise a single multi-connector. The actual layout of objects inside an enclosing component is arbitrary and is left to the discretion of the component designer.

Note: The distinction between input and output synapses is used to show the direction of signal flow. In neurobiology, there is only one synapse that connects pre and post-synaptic cells. Internally there is only one synapse that connects two cells.

Control-Alt-Del Component

The Control-Alt-Del component (see figure below left) is a high-level component because it consists of other components. Its purpose is to detect when the user presses three keys (control, alt and delete) in succession and holds all three keys down momentarily. The component fires a single signal as a result. Its output may be connected to as many other components as needed. It receives six key inputs, three for up and three for down motions. It contains three low-level components as follows:

The Sequence Component. Detects whether the three keys were pressed in the correct order.

The Keys Down Component. Detects whether the keys are held down.

The Recall Trigger Component. This is a timer component that starts on receipt of a Delete-down signal. It waits one cycle before outputting a signal. This is the trigger signal that actually conducts the test.

Sequence Component

Double-clicking on the Sequence component opens it up to reveal a single memory cell (above right). The cell is preset to remember if the three keys were pressed in the right order. If the preset sequence condition is satisfied, the memory cell will emit an output signal on receipt of a recall signal.

Keys-down Component

This component has four cells, three memory cells and a temporal cell. The memory cells are used to determine if all the keys are pressed when the component receives a Recall signal. Each memory cell receives both key-down and key-up inputs because it has to make sure that the key went down and did not go back up. Note that the Recall input is connected to every memory cell so as to activate them simultaneously. The temporal cell is used as a coincidence detector. It fires if all three keys are down and they were pressed in the right order. Note the Sequence In connector. It receives its input from the Sequence detector which sends a signal if the keys were pressed in the right order.

Trigger Component

This is a timer or wait component. It receives an input signal from the Delete-key-down sensor, the delete key being the last key to be pressed in the sequence. The timer waits one cycle and sends a recall signal to all memory cells simultaneously. If all the memory cells fire simultaneously, it means that the proper key sequence was detected.

Design Note

I could have placed all the cells inside the Keys Down detector and eliminate all but one component. I chose to separate them because it is a good exercise that demonstrates how multiple components can be connected together to form a new high-level component.

Quick Sort Component

To be continued...

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Last Update: 08/07/2002

Send all comments to: louis.savain@sbcglobal.net