Seven Segment Display

The purpose of this exercise is to teach students three things:

• About seven segment displays, an historical artifact of digital circuitry;
• Encoding a letter or number as a sequence of segments on the display; and
• Doing the encoding in JavaScript directly within the SVG file instead of in an HTML file.

This seven-segment alphabet can display all characters except k, m, v, w, and x. The letter Z is the same as the number 2, which may be confusing. Likewise with G and 6, and also S and 5.

You can change the color by appending a comma and a color to the string used to call up the SVG. Try changing the color here.

You can also change the color of the "off" segments by appending another comma and a second color to the SVG URL string. Try changing the "off" color here. Note that you can change the off color to the same color as the page background color, which renders the "off" segments invisible.

You can generate your own custom message.

SVG URLs have the format   seg7.svg#a,green,silver.   The two colors are optional. Try typing a URL here to print it. You can use the controls above to change the colors later.

The traditional use of seven-segment displays is in electronic devices such as clocks and watches.