1. A programmable read-only memory, comprising: at least one memory cell array having a multiplicity of memory cells, a multiplicity of memory segments composed of said memory cells and in which data and program parts can be stored, and a multiplicity of redundant memory segments composed of said memory cells and each associated with at least one of said memory segments, in each case one of said memory segments and associated redundant memory segments together form a memory block in which said memory segment and said associated redundant memory segments have the same data content, and said memory segment and said associated redundant memory segments of said memory block can be read, erased and/or written to simultaneously.