Alphanumeric LED displays are available in several main variations.
The 7-segment numeric display remains the most common of these displays. Many devices including industrial controllers have displayed alpha characters on these displays and while acceptable for some characters (A, b, C, d, E, F, etc.) many characters were comically indecipherable without a code book from the manufacturers.
Less popular, but far superior when alpha characters have to be displayed, are the ‘starburst’ alphanumeric displays referred to as 14-segment and 16-segment characters (ignoring the DP). Starburst displays provide an economical way of showing the full 26-character Roman alphabet in upper case, as well as the numerals 0 to 9. The difference between the 14-segment and the 16-segment digit types is that the top and bottom bar is split on the 16-segment digit, improving the appearance of some characters.
Small displays use one die per display segment, while large displays may use two or more dice per segment to spread the light effectively and show reasonably uniform intensity across the segment.