The InfoTaskForce was a group of Infocom enthusiasts who first reverse engineered the Infocom Z-Machine and wrote a public domain version in C.
The ITF started in 1986 when an Australian adventure game player was playing "Hitchhikers Guide to the Galaxy" and wondered whether there was a way to see all the humorous text in the adventure. He disassembled the CP/M Z-Machine interpreter and found out how Infocom was able to simultaneously release their adventures on multiple platforms: they were using a virtual machine. He changed from playing the adventures to disassembling the interpreter to understand its instruction set, memory map and its method of storing the adventure's objects.
A group of friends realised that by re-writing the interpreter, they could play Infocom adventures on any machine they chose, so they got together under the name of the InfoTaskForce and began to write it in C. In 6 months they finished a Version 3 interpreter and uploaded it to a local FTP server for their use. Word leaked out and the ITF interpreter proved popular, not just because it allowed people to play games, but allowed them to understand the inner workings of the Z-Machine.
Over time, other interpreters appeared on the scene which supported the newer Version 5 features to varying extents, so in September 1992 the ITF created a second and final release of the ITF Interpreter which supported Version 5 features.
The ITF Interpreter was bundled by Activision in their later release of "The Lost Treasures of Infocom."