The front panel assembly encompasses the Switch & Display Board and the Front Panel
Memory Board (FPM). Both come in at least two flavours. Oddly it would appear that
Racal only fitted back-
The photographs above show a basic non-
The photographs on the right show two clearly different types of FPM board … the
(earlier) light green version is clearly not as wide. This is because this is a pre-
The FPM board, as its name suggests, is in part a memory board. Two EAROM chips, U13 & U14 (ER3400) retain such information as mode settings as input via the front panel keys. Also included on this board is the circuitry associated with the optical shaft encoder and in the case of the board in the bottom photograph, the BITE monitoring multiplexor, U31 and U32.
Finally, the FPM board serves to distribute all non-