The MSX computers regularly had two cartridge ports. Some cartridge games by Konami had extra features and cheats that could be triggered by inserting certain o

The MSX computers regularly had two cartridge ports. Some cartridge games by Konami had extra features and cheats that could be triggered by inserting certain other cartridges to the secondary port. Here is a list of them: http://www.msxblue.com/manual/romcombis_c.htm http://www.msxblue.com/manual/romcombis_c.htm