MC6850based

MC6850based refers to hardware designs and systems that use the MC6850 asynchronous communications interface adaptor as the serial UART core for 6800-family microprocessors. The MC6850, produced by Motorola, provides a straightforward means to implement RS-232 serial communication between a CPU and peripheral devices, handling both transmission and reception with interrupt support.

Architecturally, the MC6850 exposes an 8-bit data port connected to the host processor’s data bus, along with a control register and a status register. It contains a data register used for both transmitting and receiving data, a status register that flags conditions such as transmit data register empty and receive data register full, and a control register to enable the transmitter and receiver, configure the character format, and control interrupt behavior. The baud rate is derived from an external clock, typically via a divisor or baud-rate generator, allowing operation across a range of speeds when paired with suitable line drivers.

Operation is straightforward: the host writes a byte to the data register to initiate transmission, and the MC6850 asserts the transmit interrupt or flags TDRE when ready for more data. For reception, incoming data is loaded into the data register and the RDRF flag is set, with an interrupt signal if enabled. The CPU reads the received byte from the data register and clears the flag accordingly. The interface typically connects to a RS-232-compatible line driver or transceiver for voltage level shifting.

In historical context, MC6850based implementations were common in early 1980s microcomputers and embedded systems using the 6800 family. They remain of interest to vintage computing enthusiasts and retrodesigns, often complemented by external line drivers to complete the serial link.