 Several competitors, such as Siemens (later Infineon Technologies, now Intel Mobile Communications), NEC, Texas Instruments, STMicroelectronics (formerly SGS-Thomson), Motorola (later Freescale, now merged with NXP), Nordic Semiconductor and Intersil, have introduced compatible I2C products to the market since the mid-1990s.System Management Bus (SMBus), defined by Intel in 1995, is a subset of I2C, defining a stricter usage.One purpose of SMBus is to promote robustness and interoperability.