I searched the forums, but I didn't find this mentioned. I just found out that the "Color Bar Generator" cartridge from Videosoft was published in the "Radio Electronics" magazine as a DIY project. The article can be found in the August 1984 issue, pages 41-43 (you can download it from here). In the article by Jerry Lawson and Dan McElroy there are PCB layouts to etch your own board, a list of components (which only consists in the eprom and inverter IC) and a brief overview about the VCS hard