The Psion Siena is a personal digital assistant made by Psion PLC and was released in 1996. Two versions of the Siena were released, one containing 512KB of memory and the second with 1MB.
The main power is provided by two AAA batteries and the backup power by one cell-style CR1620 battery. The batteries are held in a compartment below a detachable casing in the top of the device. It does not have a socket for an external power source.