X-ray diagnostic installation for x-ray photographs

Program control apparatus for the photographic operating sequence of an x-ray photographic installation comprising a series of memory circuits for storing respective photographic program sequences, a resettable pulse counter being connected with the address input of each of said memory circuits for sequentially selecting the program steps of the respective memory circuits, a pulse generator for supplying program signals to the pulse counter for sequentially selecting the program steps of the respective memory circuits, and a program selection circuit connected with the outputs of the memory circuits for transmitting the output signals from a selected one of the memory circuits, wherein the improvement comprises a correction memory (60) for selectively storing respective corrected photographic program steps representing corrections for selected program steps of said memory circuits, said correction memory (60) having an address input connected with said resettable pulse counter (49) for enabling the selection of the corrected photographic program step corresponding to the count of said pulse counter (49), and having an output connected with said program selection circuit (56) for supplying such corrected photographic program step thereto, a correction recognition memory (63) having an address input connected with said resettable pulse counter (49) and operable for storing correction signals for identifying the counts of said pulse counter (49) for which the respective corrected photographic program steps are stored in said correction memory (60) and having a correction recognition output connected with said program selection circuit (56) for signalling the program selection circuit (56) when a stored correction signal in said correction recognition memory (63) corresponds to the current count of said pulse counter (49), said selection circuit (56) having selection switch means (56a) controlling the selection of said correction memory (60) for control of the photographic operating sequence, and being connected with said correction recognition output and responsive to said signalling therefrom for disabling transmission of the output signals from the selected one of the memory circuits and for effecting in place thereof the transmission of the corresponding corrected photographic program step from said correction memory (60).