"Breaking Seal Voids Warranty" -- to most people, this little sticker affixed to consumer-electronics hardware might as well be a law of nature. They plug in their gadget and turn it on but would never dream of opening it up.
To some, though, that little sticker is a challenge. People with the curiosity and technical expertise often crack open the cases to find out what goes on inside those mysterious gizmos -- and sometimes make them work better.
Two products in particular have become popular with hackers lately: the ReplayTV and TiVo "personal video recorders." These VCR-like machines save and play back television programming using hard drives rather than videotape. By adding a larger hard drive to a Replay or TiVo, a hacker can double or even quadruple the number of shows their PVR can record -- a $250 drive can boost an older Replay box's capacity from 20 hours to 80. Some hackers go even further with tricks like adding an Ethernet card for networking to a computer or enabling PAL-format video output for use in other countries.
The TiVo is particularly popular among hackers, in part because it uses the Linux operating system that many technically inclined computer users run on their own PCs. ReplayTV is more difficult to hack because it uses a proprietary operating system.
The number of people who have modified their PVRs is not known. Hacking is "pretty much limited to a small group of technophiles who like tinkering," said Steve Shannon, vice president of marketing at ReplayTV. "I could probably count them on one hand."
Dawn Banks, one of the creators of RTVPatch, software needed to upgrade ReplayTV, doesn't know either but thinks the number is higher. Hundreds of people -- "maybe a thousand or more" -- have downloaded Banks's program, although not all of these people actually use it.
It takes more than just curiosity to open up one of these devices and start messing with wires and connectors. Adding storage space to a PVR is "for the person who doesn't mind voiding a warranty, who doesn't mind taking the risk of ruining their unit and who is adept enough to add a new hard drive to a PC," Banks said. The risks of opening a consumer electronics gadget like the ReplayTV and TiVo -- including electrocuting yourself, should you touch a screwdriver to the capacitator inside -- are very real. Although there have been no reports of people zapping themselves, intrepid hackers have indeed maimed or killed their boxes in their attempts to upgrade.
"There are many ways to turn your $500 box into a paperweight," said Sean Riddle, a network manager in Manassas who has extensively customized his ReplayTV.
Although most PVR hackers simply add storage space, Riddle delved deeper into his ReplayTV. "I've got a 140-gig Replay, have it connected to my PC for control, programmed my own screens for the unit, and just finished building an interface to connect it to my PC to update channel guide info over my cable modem," he said.
His custom menu contains features only a hacker, or a control freak, could love, including the ability to micromanage recording quality and the speed of the internal modem (used to update Replay's on-screen programming guide), flash the front-panel LEDs, and run internal tests.
"I've also written a PC program that can edit the cable lineup file," he added. "When Comcast switched SpeedVision and Comedy Central, I swapped them in the Replay file so I wouldn't miss any BattleBots shows."
Although the makers of these products do not officially condone hacking, they exhibit a nonchalance that is perhaps surprising. "As long as people are only affecting themselves and accepting the potential risks, it's not a big deal to us," Shannon said. "If it was affecting other users or content security, then it would be a big deal."
There is a fine line between innocently enhancing a product that you bought and becoming a nuisance to its manufacturer -- and most hackers are careful not to cross it. For instance, access to TiVo's television schedule comes with a subscription fee, but the authors of the TiVo Hacking FAQ (frequently asked questions) file explicitly state that they're not going to explore ways to defeat the subscription requirement.
Hardware hackers typically share their insights at special-interest Web sites. Information about hacking ReplayTV can be found at www.replaytvfaq.com, while comparable TiVo details are at www.tivofaq.com/hack/faq.html. The AV Science Forum (www.avsforum.com) is a popular spot for users of both systems.
Hacking efforts are not limited to television watchers. John Mechalas, a Portland, Ore.-based systems administrator, is leading an effort to decode the communications protocol used by Creative's Nomad Jukebox, a popular MP3 music player (www.aracnet.com/~ seagull/NJB/). Once the device's language is decrypted, programmers will be able to write new programs to control the Jukebox.
For instance, Mechalas prefers the Unix operating system, but the Jukebox ships with software for only Windows 98 and 2000, as well as the Mac OS. By decoding the unit's communications protocol, programmers can create software that runs on other platforms.
Mechalas and his fellow hackers may not get there. But that's not quite the point. The "hackability" of a product can be appealing in its own right to some customers -- the ones who are curious, technically minded or cheap. To a hacker, a modification doesn't even have to be particularly useful -- just elegant. Dawn Banks, the RTVPatch author, sums it up succinctly: "It makes some people feel like they're getting something extra, just knowing the hack is there."