The invention relates to a data processing installation with a working memory addressable by a controller which can be switched to its various memory areas by signals. To make the switchover as simple as possible, each working memory area (e.g. A3) has in its program storage field (e.g. P3) at least one global function (F3) which can be called from at least one other working memory area (e.g. A1). In each working memory area (e.g. A1) there is at least one predetermined function (F1) from which a transfer can be made to an identical function as a simulation function (F2). A changeover routine (e.g. U1) is linked on the one hand to the simulation function (F2) of the same working memory (e.g. A1) and on the other to a changeover routine (e.g. U2) of the other working memory (e.g. A3) in which the global function (F1) allocated to said simulation function (F3) is stored. A shared changeover module is allocated to all the working memory areas (A1 to A4).
