Well, first, understand that there are two different ways to achieve band scope functionality with the TS-850. One is the ACC1 jack, the other is the IF OUT connector. (Note: in my previous post I mistakenly identified the computer control port as ACC2. It really is ACC1. Sorry for the confusion.)
The computer control connection via ACC1 gives you a way to issue commands to the radio and query its status. You can tell it to go to a specific frequency, change modes, select a memory channel, query the signal meter reading, key up the transmitter, etc... It's really just a 4800 baud serial connection. There's a separate manual that comes with the TS-850 that explains the command syntax. You can connect a terminal program direct to the radio and type in the commands manually to experiment with it. (For example, typing "ID;" will cause it to return a model ID code, which I think for the TS-850 is ID0009.)
The IF OUT jack provides a tap of the receiver's 8.83Mhz IF stage. It's normally meant to be connected to the Kenwood SM-230 station monitor, which has a built-in band scope feature. It's analog though, not digital. (I have the SM-230; it's a nifty accessory.)
The best way of generating a band scope display is to use the IF OUT port, and I know people have built interfaces so that you can sample the IF OUT signal via a typical computer sound card. I think there's also at least one 3rd party manufacturer that makes a nice digital pan adapter unit that can be configured to work with the TS-850.
However, it seems the Ham Radio Deluxe software can use an alternate approach that uses just the computer control interface, where it sweeps the radio across the band and records the signal meter readings in order to create a graph of activity above and below your currently selected frequency.
The only problem with this is that you generally can't listen to your current frequency and gather the signal meter samples at the same time (the program has to keep sweeping the receiver around to gather data), and with the TS-850 gathering samples will be a bit slow since the serial interface operates at only 4800 baud. So it's questionable how useful this feature can be.
Anyway, I didn't use Ham Radio Deluxe, since I don't run Windows on my computer. I found an open source program called GRig, which works in conjunction with the Hamlib software. It worked ok, but was a little clumsy (GRig is old and fairly basic).
Like I said, the interface did work, but the fact that it wouldn't work in conjunction with the DSP-100 unit was a bit of a let down.
-Bill