100 may also interoperate with peripheral devices in addition to jackets 200 one of the many challenges in developing and manufacturing communicator 100 is the requirement of miniature size and reliable connection to jackets 200 as such communicator 100 is pin limited in one implementation of the present invention a 12 pin interface is used to provide both a full communication bus for complex jackets and an interface for jacket identification and keypad decoding for simple jackets the 12 interface pins provide multiplexed functionality for four operational stages functionality switches according to transitions from a current stage to a next stage as described in detail hereinbelow reference is now made to fig5 which is a high level circuit diagram for a first jacket in accordance with an embodiment of the present invention reference is also made to fig6 which is a high level circuit diagram for a second jacket that includes a serial nor flash memory 250 in accordance with an embodiment of the present invention components of communicator 100 are shown to the right of connector 120 220 and components of jacket 200 are shown to the left of connector 120 220 as shown in fig5 and 6 connector 120 220 uses 4 pins pins 26 29 for keypad columns 5 pins pins 18 21 and 24 for keypad rows one pin for activating backlight 263 one pin for activating vibrator 264 and one additional pin connected to a level shifter 111 a single pin pin.