While it's simple enough to build a "Wiggler" JTAG adapter for the PC parallel port, there is very little open hardware for performing high-speed programming of JTAG devices by USB. This lecture introduces the GoodFET, an open source USB JTAG adapter which can be reflashed to support the programming and debugging of any number of chips. Both hardware and firmware are compared to that of a similar, commercial design.
This lecture will also cover the details of the JTAG standard and a few of its competitors, as well as the possibility of attacking these debugging modes when access has been denied or restricted.