What is the BDM board ?
The BDM board (BDM stands for ‘Background Debugger Module’) is used to communicate to the CPU board from a PC. You won’t be able to do much without one of these. Currently, there are about 3 or 4 different BDM boards floating around. The oldest is known as the ‘2 chip’ and has (surprise, surprise) 2 ICs on it. The newest is the ‘5 chip’ board, and is generally regarded as being a better design. There is also a BDM board floating around that is based on a GAL (General Array Logic??). This BDM is built around an In-System-Programable (ISP) GAL. The logic had been worked out, but there were inconsistencies between the hard burned GAL and the ISP GAL chips. To quote Gunter Magin (the designer of the GAL BDM): “The intent behind the ISP solution was that people should be able to build the interface even if they don’t have equipment to burn a GAL. The PP of the PC (and some software) would be their poor-man’s GAL programmer. And: it would be flexible for using the PP for other BDM-alike prot
