I think the .dat file is one that you can save from your DSP, It saves all the step pulse settings and user changeable DSP settings. It doesn't save the inbuilt software. (I think
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The initial program seems to be a basic operating system that the DSP reverts to when it is booting up. The main program it seems to use it the one that oyu cant get to load (as yet)
I have sent you version 1.3 of the signtek software, hopefully that one works.
I will check both of them on my DSP when at my workshop today.
Shannon.