preCopywriteR is used to generate helper files (blacklist, bin region, GC-content, and mappability .bed files) for the desired bin size from pre-assembled 1 kb helper files. These binary 1 kb helper files are available at https://github.com/PeeperLab/CopywriteR for hg18, hg19, hg38, mm9 and mm10 reference genomes.