The TS80C51U2 retains all features of the 80C51 with extended ROM/EPROM capacity (16 Kbytes), 256 bytes of internal RAM, a 7-source , 4-level interrupt system, an on-chip oscilator and three timer/counters. In addition, the TS80C51U2 has a second UART, enhanced functions on both UART, enhanced timer 2, a hardware watchdog timer, a dual data pointer, a baud rate generator and a X2 speed improvement mechanism.