This isn't for doing evil, I swear.

Just a quick unbuffered JTAG for my Motorola Surfboard 5101 cable modem. It was $10 used and needed a flash back to non-hacker firmware for use on Comcast HSI. I got the JTAG pinout from a cable modem hacking forum, wired it up, and connected it to my account with no issues.

Board extracted from the cable modem shell on a table along with wire, solder cup jack, and pinout drawn on a sheet of paper. Six JTAG lines soldered to the points on the SurfBoard. The parallel port connector on the other end of the JTAG wires. The modem reassembled after JTAG installation. The LEDs are lit on the front. Rear view of the finished job showing the slot carved out of the top plastic for the JTAG wiring.

I left the JTAG attached afterward, leading to some weird looks from Comcast techs when they came to hook me up.