ZD-Bug 1.1 API documentation:
----------------------------
As of yet, the API is pretty sparse. There is one call and a few special
memory locations. The call is conditional: it will only work while the ON key
is pressed, allowing you to stop debugging for a while, then start again
later.
WARNING: Never use these values with an older or newer version of ZD-Bug!
NOTE: Though I've never tried it, these should work within greyscale programs
and graph memory based interrupt handlers.

CALL: (yes, it's not plural)
        call ($9353)            Opens the popup if the ON key is pressed.
                                (it even works if ZD-Bug is inactive, as long
                                as if it was activated prevously)

ADDRESSES:
        $90A4 (2 bytes)         The address of the top value in ZD-Bug's
                                popup

        $90B1 (1 byte)          The magnitude of the delay (delay function)
                                Obvously this can't be used within interrupt
                                handlers and greyscale programs.

        $9101 (1 byte)          Debug status: (as long as ZD-Bug is loaded,
                                you don't have to check this)
                                -$92: If ZD-Bug was the last ZShell-extending
                                 interrupt handler you used, API use is safe
                                -Anything else: API use will crash you calc