ProTracker is a popular freeware tracker created by Lars Hamre, Anders Hamre, Sven Vahsen and Rune Johnsrud for the Amiga platform. It is among the first programs that allowed for widespread creation of music without studio equipment. It was popular for amateurs and professionals, and set a standard for the MOD fileformat. Tracker is the generic term for a class of software music sequencers which, in their purest form, allow the user to arrange sound samples stepwise on a timeline across several monophonic channels. A tracker’s interface is primarily numeric; notes are entered via the alphanumeric keys of the computer keyboard, while parameters, effects and so forth are entered in hexadecimal. A complete song consists of several small multi-channel patterns chained together via a master list. Protracker music lives on today. It can be found in modern computer games such as the Unreal series and Deus Ex, as well as a considerable number of indie games. However, the easy availability of software samplers/synthesizers and sequencers has caused most professional musicians to adopt other music software. Nonetheless, tracker software continues to develop (as of 2007). Some of the early Amiga trackers such as ProTracker, OctaMED have received various updates, mostly for porting to other platforms.