I think the biggest hurdle is just turning the waveform into a "sensible" series of 1's and 0's. The right stream of 0/1 could be converted into the bytes - that's essentially what my simulator does, because the microcode generates 0/1 on the tape data output. To me, the hard part is the handling of the digitized signal and detecting the transitions and getting the timing right. Once it is 0/1's then it is relatively easy. I also have code in the simulator that turns bytes back into a stream of 0/1's with timing, since that is what the microcode needs for LOAD PROG. But, we'd need some hardware - similar to the tape write circuitry on the 700 - to turn that stream of 0/1's back into flux changes on the tape. I think it is all doable, but I'm not in a position to tinker with the necessary hardware right now. If we're building a modern Wang 700 tape drive, though, we might as well make it do the read as well as record, and then the cassette-USB adapter isn't needed. Note that the Wang tape drive accepts TTL logic 0/1 on input (record) and produces 0/1 on output (playback), and we have schematics, so we could in theory build a modern equivalent. Then with a bitstream interface, it becomes a lot easier to read and write Wang 700 tapes on a PC (or rPI or ...).
