Zinwell ZAT-970A Owner's Manual says that you can go to a Software Update menu, but didn't provide any screen shots re this feature, so maybe it exists in final products and maybe it doesn't:
Manual says that there are two methods:
1) RS-232, but is ONLY for factory use (I can see RS-232 area on a picture of circuit board but TXD/RXD/GND/5V thru-holes are NOT populated with any pins for a connector).
2) OTA, which they say is via "cable"....which would (incorrectly???) IMPLY you need to attach it to a CATV system for "OTA" update....but perhaps they really mean what they call it: "OTA"....so worth a try anyway.
Both CATV and OTA systems have implemented a digital stream that cycles through software updates for THOUSANDS (???) of different products that have arranged for OTA Update Broadcast as just one more Data Stream in the MPEG2 Multiplex:
Note that Update Logic also provides a USB Stick mail-out service if you wanted to fabricate your own RS-232 Cable (and figured out whether "TXD" was FROM board or FROM external device...I would trace back to see which went to driver and which to receiver IC).
Your PBS station KERA provides UPDATE-TV per RabbitEars Market summary for DFW:
As far as I know, some (most?) PBS Stations provide this service, so you'll have to set the Converter up on a PBS channel and let it listen for perhaps several days before the ZAT-970A update comes up in the extremely long sequence....it's also possible that once you enable the Software Update function, it will listen for the periodic time table of events and will automatically turn ON and tune to PBS at the appointed time....not sure how any particular box implemented this functionality....and it would be worth a call/email to Update-TV and/or Zinwell Service to query whether an update even exists....it would also be worthwhile to search Forum for other people's experience with OTA Software/Firmware Updates....Edited by holl_ands - 2/7/13 at 2:47pm