For bootstrapping Jam an external make or MMS is required. Since it has only a few source files, it can also be compiled manually. All system dependences are collected in two different files, which exist for every operating system type. The first is used to get information about files, e.g., the modification time, and the second is used to execute a command, e.g., a compiler or linker. If Jam is adapted to a new operating system, only these two files need modification or extensions. Currently there is support for the various UNIX dialects, VMS and WindowsNT.