The W77E516 is a fast 8051 compatible microcontroller with a redesigned processor core without wasted clock and memory cycles. As a result, it executes every 8051 instruction faster than the original 8051 for the same crystal speed. Typically, the instruction executing time of W77E516 is 1.5 to 3 times faster then that of traditional 8051, depending on the type of instruction. In general, the overall performance is about 2.5 times better than the original for the same crystal speed. Giving the same throughput with lower clock speed, power consumption has been improved. Consequently, the W77E516 is a fully static CMOS design; it can also be operated at a lower crystal clock. The W77E516 contains In-System Programmable (ISP) 64 KB Flash EPROM; 4KB auxiliary Flash EPROM for loader program; operating voltage from 4.5V to 5.5V; on-chip 1 KB MOVX SRAM; three power saving modes.