Small fonts have always been fascinating to me, so I decided to make the smallest font possible, which turned out to be 4x4 pixels per character. The font covers the entire range of visible ASCII characters, and most are immediately recognizable. A few characters had to be modified to fit within a 4x4 box, most notably the number sign (#) and the lower case x. I carefully designed the font so that no two characters share the same bitmap.
Although I didn't design this font with any particular function in mind, it would be useful in any situation where compact text is needed, such as on extremely low resolution displays. Feel free to use it for whatever you like.
Improved the lower case "a".EDIT: 5/24/2018
With the help of an online font editor, I was able to rapidly test this font with sample text. This revealed a number of readability issues, which I was able to improve with a few minor modifications. After extensive testing of this revised font, I was unable to find any words or sentences which were illegible or lacked fluidity, so I now consider it complete.