The 32K EPROM has a monitor in the first 1400h bytes, and the rest is just blank (FFh).

The software comes in three versions, communicating through a Z80 FIFO, single-byte latch, or serial port. Monitor versions are available for different default console devices.

4732-00 uses Serial Channel 0
4732-01 uses Serial Channel 1
4732-02 uses STEbus FIFO Mailbox

I have only the -00 version.

The manual includes source code for the initial entry points.

I've not disassembled the rest of the code yet.