What were the precursors of Crispr/Cas9 and what were their disadvantages?

Meganucleases; only bind to a very specific DNA stretch and is only useful if this specific stretch is your gene of interest, cannot be targeted. zinc finger nucleases; can be targeted, but can only target specific sites (e.g. only 1000 genes can be targeted). TALEN; can be designed to any target site of the genome, but they are not very efficient and it takes a long time (weeks/months).