Microprocessors emerged in the early 1970s and were used for electronic calculators. In the 1970s and 1980s, 8-bit and 16-bit processors were developed by Intel and others. In the 1980s, RISC microprocessors were introduced and gained widespread use. While 64-bit designs were used in specialized applications in the early 1990s, they began to be used in PCs in the early 2000s. By the late 1990s, the main 64-bit architectures were SPARC, Power, and ARM which became increasingly powerful.