We started working with three different models of digital-to-analog converter boxes distributed by Digital Stream (Radio Shack), RCA, and Zenith. The Digital Stream converter box – specifically, model #DTX9950 – turned out to be the most “hackable” of the bunch (both software and hardware/circuit board). Interestingly, it was the least expensive.
Eric and Dave Jones were able to pull-up info which let us know which version of the Mircro C/OS the Digital Stream was running (uC/OS-II). This device responds to the App_Pause_SMTask command that pauses the signal monitoring and keeps the converter from resynching “bad video,” allowing us to apply hardware hacks without losing signal. Being able to access terminal commands within the Digital Stream and over-ride its “bad video” resync function was certainly key to getting our hardware hacks to work!
We also learned that the DTX9950 was built in December of 2010 after the digital TV conversion date of June 12, 2009. Interesting stuff, but we still don’t have a clue why this particular box was “hackable.” These boxes are incredibly obtuse, overall — no service guides are available and with over 4,000 functions, manually identifying each one would take more time than we have available.