With this knowledge, I dug into the rest of the boards, and found the following:
- BBP-100: Binary Bit Processor, basically the primary difference in the “Mark II” model
- KOS-100: Keyboard-Operated-Send board; enables send mode directly from the TTY
- TMS-100: Board that allows you to specify 3 programmable sets of mark/space frequencies, select-able via a knob on the front
- TID-100: Adds the ability to send a pre-programmed* CW ID
What’s interesting about that last board, the TID-100, is that it’s “programmed” by filling in a matrix of slots on the board with diodes, not unlike an ID barrel on a Teletype where you break off plastic fingers to program a message. You want a “dash”? 3 diodes in a row, then an open space. You want a dot? That’s a single diode, then another space. Unfortunately I’d have to add an additional 16 diodes to re-program it for my call sign. We’ll see if I feel like dealing with that down the road.
So all in all, while this unit isn’t quite bare-bones, it’s lack of TSR board means a lot of the features and controls on the front are just for show. That’s OK though, I don’t necessarily need all that jazz, I really just wanted a cooler-looking TU with a cross display, and if I go through with re-programming the TID-100 board, that’s an added bonus. For now I’ll get it back together, get it hooked up to the TTY, and try to make some noise with it.