The Scorpion Controller, unlike many of its bedmates, is intelligent and - being battery backed- up - it can be operated independently of its Spectrum host.
A CMOS microprocessor on board the black box, and a control language with the structure of Logo and speed of Basic make the device intelligent. The Scorpion's 24K battery-backed Ram means that, once it's been programmed, you can unplug the controller from the back of your Spectrum and take to your robot. Your program will be executed by the integral microprocessor until you switch off the battery.
The unit is approximately half the size of a Spectrum 128K +2, lightweight and portable. It's ideal for driving buggies and robots in areas away mains supply.
Scorpion can control up to four Beasty servo units - see separate review. It boasts four digital outputs, which can drive small DC motors or through a system of relays larger motors. An additional external driver board can be added to run six stepper motors.
Other interface links include an LCD display driver, a 20 key keypad input socket, a Phillips 12C port and a system expansion connector.
Scorpion is an all-in-one interface which you could carry around in a briefcase if need be. It's simple command language provides an entry point for beginners and its portability between different types of computer allows robots, buggies and other devices which operate on BBCs or QLs to work with your system.
The only unit reviewed which was both independent and intelligent. Its control language is high level - no Peeks and Pokes required - and its portability allows you to set up devices away form home. Expensive.