Abstract: In order to reduce the time losses that arise when reading a plurality of successive data blocks, because of the interruption of the read operation in the case of recognized data errors, all required data blocks are read in one pass and are transferred into a correspondingly enlarged buffer memory (DAT-SP). Error syndromes (ES) resulting from the recognized data errors are initially intermediately stored in allocation to the erroneous data, until a correction of the data in the data memory (DAT-SP) is possible.

Abstract: The storage tracks lying respectively above one another in a disk pack and yielding a cylinder are divided into sectors, whereby a respective plurality of sectors have one respective alternate sector assigned thereto, the latter serving as a useful sector in case a defective sector occurs along the track. The assignment of the defective sectors to the alternate sectors is controlled in such a manner that every occurring defective sector effects a shift of the defective sector and of the following sectors by respectively one sector up to the respectively next, following alternate sector, the shift amplitude after every alternate sector being reduced by one sector length or, respectively, to zero and, in turn, corresponding increased at every following defective sector within the cylinder up to the next alternate sector following thereupon.