High Quality Content by WIKIPEDIA articles! Programmer`s Notepad (PN1) is an open-source text editor targeted at users who work with source code. It was released in 1998 by Echo Software (a trading name for Simon Steele). PN1`s successor, Programmer`s Notepad 2 (PN2), was released in 2002 and is now based on Scintilla. Possibly the most distinctive feature common to both versions is the combination tabbed document interface and multiple document interface called "Tabbed MDI" by the developer. The TDI is parent to the MDI.