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Atmel offers a powerful ROMless 8051 microcontroller suitable for existing ROMless applications that require a combination of performance, flexibility, and power efficiency. The AT80C51RD2 microcontroller retains all features of the Atmel 80C52, with 256 bytes of internal RAM, a 7- source 4-level interrupt controller, and three timer/counters.
To enhance system performance, this ROMless microcontroller features a programmable counter array, an XRAM of 1024 bytes, a hardware watchdog timer, and a keyboard interface. It also includes a versatile serial channel that facilitates multiprocessor communication (EUART), and a speed improvement mechanism (X2 mode).
80C51 High-Performance ROM 8-Bit Microcontroller