There are two versions:
* The first one does not require a power supply input and has a switch on top. It does not provide compatibility with CP/M.* The later one does not require a power supply input and does not have a switch. Compatibility with CP/M is provided.
The original version was first advertised in April 1985, these adverts didn't mention whether or not it requires a power supply input (normally, its data latch should need a power supply).