The successor to the Pentium Pro from Intel. Pentium II refers to the CPU chip or the PC that uses it. Code-named Klamath, the Pentium II was a Pentium Pro with MMX multimedia instructions. Introduced in 1997 at clock rates of 233 MHz and 266 MHz, it used a 66 or 100MHz system bus and introduced the Single Edge Contact Cartridge (SECC). The Pentium II chip used variable power voltages. See Pentium and SECC.