Capcom placed a heavy emphasis on fighting arcade bootleggers by the late 1980's, with Capcom president Kenzo Tsujimoto describing one of the main features of their CPS-1 arcade hardware being their various copy protection methods. By 1991, CPS-1 games incorporated "suicide batteries" connected to games' graphics to deter attempts at bootlegging, but the CPS-1 hardware was widely copied despite this. When Capcom released their CPS-2 hardware in 1993, every board in the system used a suicide battery, and the CPU was encrypted with a decryption table stored in battery-backed up RAM. Once the battery ran out, the PCB became defunct. Though criticized, this method prevented the CPS-2 from being bootlegged during its lifetime, with its encryption only being cleared in 2007.