WDC 65C51

The WDC 65C51 is a CMOS Asynchronous Communications Interface Adapter (ACIA) designed by Western Design Center (WDC). It is a versatile serial communication peripheral used primarily with 65xx family microprocessors like the 6502. The 65C51 provides a full-duplex asynchronous serial interface capable of baud rate generation and various data formatting options.

Key Features and Characteristics:

• Asynchronous Communication: Operates using start and stop bits to frame data, eliminating the need for a shared clock signal between communicating devices.
• Full-Duplex Operation: Allows simultaneous transmission and reception of data.
• Programmable Baud Rate Generator: Contains an on-chip baud rate generator that can be programmed to support a wide range of communication speeds.
• Data Framing Options: Supports various data word lengths (typically 5-8 bits), parity options (even, odd, or none), and number of stop bits (1 or 2).
• Interrupt Capability: Generates interrupts to signal various events, such as reception of data, transmission buffer empty, or error conditions.
• CMOS Technology: Implemented in CMOS technology, offering low power consumption.
• Status and Control Registers: Provides registers for configuring communication parameters, monitoring the status of the serial interface, and controlling its operation.
• External Clock or Internal Baud Rate Generator: Can use an external clock signal or its internal baud rate generator.

Typical Applications:

The WDC 65C51 finds use in a variety of applications requiring serial communication, including:

• Computer Peripherals: Interfacing with modems, serial printers, terminals, and other RS-232 devices.
• Embedded Systems: Connecting microprocessors to serial communication networks or devices in embedded applications.
• Data Acquisition: Serial data transfer between sensors, data loggers, and processing units.
• Industrial Control: Communicating with industrial control systems and devices using serial protocols.

Relationship to Other ACIA Chips:

The 65C51 is often considered an enhanced version of the original 6551 ACIA. It offers improved features and performance, including lower power consumption due to its CMOS construction. The 65C51 is designed as a direct replacement for the 6551 in many applications. However, subtle differences might exist in register behavior and interrupt handling, requiring careful consideration when replacing one with the other in existing systems.