[TenTec] What's an SDR?

[SS409SS at aol.com]

So a rig with an A/D convertor for transmit and receive qualifies it as 
SDR. The first ham rig I can recall having those features would be the 
TS-870. Being upgradable and having encoders for controls doesn't seem 
to matter. 
N4LQ

  Although the 870 includes the above, some of the features are embedded in physical and traditional radio hardware. The SDR's are defined by software and have such circuits which can be changed or "mode altered" if you will. Simply thru the firmware or firmware revisions. 
  For example, AM was added to the Pegasus thru a change in firmware. In the Orion, just about every aspect of the rig can be altered thru firmware upgrades. I think thats what they are getting at. Regards.. Richy N2ZD