Though not seen nearly as often with the advent of cheap VFD and LCD matrix displays, the "starburst" display can be used to display alphanumeric characters, much as the seven-segment display could display numeric characters.
A starburst typically takes one of the following forms:
----A---- -A1- -A2-
|\ | /| |\ | /|
F \ I / B F \ I / B
| H | J | | H | J |
| \|/ | | \|/ |
-G1- -G2- -G1- -G2-
| /|\ | | /|\ |
| M | K | | M | K |
E / L \ C E / L \ C
|/ | \| |/ | \|
----D---- -D1- -D2-
14-segment 16-segment
(There may also be a decimal point on some displays.)
Look familiar at all to you? You may recognize the odd-shaped letters formed by this pattern from the old Speak & Spell toys from Mattel. A few letters certainly come out looking very odd (B and D come to mind), but are still quite legible to the average reader.
Although the 14-segment version of the starburst could not display figures that relied on a half-bar on the top or bottom (such as square brackets), it was often favored over the 16-segment starburst, mainly because controller chips could be easily designed that handled either two seven-segment displays or a single 14-segment display, with no increase in pin count. Often displays would be broken into two sets of seven LEDs -- one for the upper-left and one for the lower-right, each with a common cathode. If you slow down the strobe rate for one of these displays, it will appear to flicker between these two halfs.
LED starburst displays are somewhat rare now, but you will still occasionally see VFD or LCD starbursts when a more-complicated (and more expensive) matrix-style display is not required. If you ever get your hands on some as a hobbyist, they're fun to experiment with, as the starburst pattern offers all sorts of interesting effects you can do, and for far less effort and money than a pixel-addressable display.
Here are some special effects you can do with a starburst. In the notes below, "X+Y" means illuminate segments X and Y together. Commas separate frames of animation.
- Border spinner: A, B, C, D, E, F, repeat. Obviously one of the easiest, this traces the edge of the display.
- Clock hand: G1, H, I, J, G2, K, L, M, repeat. Another simple one, does a little spinner thing around the center of the display.
- Clockwise spinning bar: I+L, J+M, G1+G2, H+K, repeat. Essentially the above but with a long spinning bar instead of a short one. Great as a "wait" prompt.
- Cloverleaf worm (16-segment only): I, A2, B, G2, G1, F, A1, I, L, D1, E, G1, G2, C, D2, L, repeat. Traces the path of a four-leaf clover.
- Bouncing bar: A, J+M, E+F, H+K, D, J+M, B+C, H+K, repeat. This looks somewhat like a cross between the above two, with a bar bouncing around the corners of the box.
- Bar graph: By using E+F, I+L, and B+C across multiple starbursts, you can create a progress bar that resembles that of Windows 95. If you use A1+A2, G1+G2, and D1+D2 on a 16-segment display, you have a makeshift three-column bargraph to use.
You can get even fancier -- creating a "pie slice" display with a 16-segment, for example, or making the cloverleaf worm longer by keeping the previous segment on for two frames (making it I+A2, A2+B, B+G2, G2+G1, et cetera). The sky's the limit! Well, that, and the physical locations of the segments.