a typeface based on a 3x3 bitmap matrix.  Identical characters for "O" and "0", "2" and "Z", "5" and "S", and "Q" and "9".
Own work, vector conversion of en:File:3x3.gif uploaded to en.wikipedia on 12:10, 18 January 2008 by en:User:Martinheras, based on font by Anders de Flon
Original GIF by en:User:Martinheras, first vector version Sphilbrick, this vector version User:AnonMoos