The MC68040, MC68040V, MC68LC040, and MC68EC040 are NXP Semiconductors (formerly Motorola, Inc., Semiconductor Products Sector) fourth generation of M68000-compatible, high-performance, 32-bit microprocessors. All four devices are virtual memory microprocessors employing multiple concurrent execution units and a highly integrated architecture that provides very high performance. They integrate an MC68030-compatible integer unit (IU) and two independent caches. The MC68040, MC68040V, and MC68LC040 contain dual, independent, demand-paged memory management units (MMUs) for instruction and data stream accesses and independent, 4-Kbyte instruction and data caches. The MC68040 contains an MC68881/MC68882-compatible floating-point unit (FPU). The use of multiple independent execution pipelines, multiple internal buses, and a full internal Harvard architecture, including separate physical caches for both instruction and data accesses, achieves a high degree of instruction execution parallelism on all three processors. The on-chip bus snoop logic, which directly supports cache coherency in multimaster applications, enhances cache functionality.