1. A data storage and retrieval system comprising: a mass memory means for storing data at locations having plural digit addresses; a random access memory means having a plurality of first memory locations for storing in each of said locations a coded word corresponding to one plural digit address of said mass memory means and a plurality of second memory locations each corresponding to one of said plurality of first memory locations for storing data; a memory control means connected to said mass memory means and said random access memory means for reading the coded word stored in each of said first memory locations of said random access memory means and for storing in each of said second memory locations of said random access memory means the data stored in said mass memory means at the plural digit address which corresponds to said coded word stored in the respective first memory locations, and for storing in said mass memory means the data stored in each of said second memory locations of said random access memory means at the plural digit address of said mass memory means that corresponds to said coded word stored in the respective first memory locations; a fixed display board having a plurality of display portions, each providing a selective indication by an indicator means; a plurality of identification means having a plurality of identification portions corresponding to said plurality of display portions of said fixed display board for being mounted upon said fixed display board to identify each of said plurality of display positions; an item selection means connected to said fixed display board for selecting one of a plurality of items each corresponding to one of said display positions identified by said identification means and for causing said corresponding indicator means to provide an indication of the selection; a plurality of magnetic card memory means each corresponding to one of said plurality of identification means for storing data corresponding to at least part of a plural digit address of said mass memory means; a magnetic card reading means for reading the data stored on said magnetic card memory means; and an address decoder means connected to said random access memory means, said item selection means and said magnetic card reading means for combining the data stored on said magnetic card memory means and the item selected by said item selection means to produce said coded word corresponding to a plural digit address of said mass memory means and for recording said coded word in at least one of said first memory locations of said random access memory means.