Chips › I/O & support › Serial & UART › Motorola 6850 ACIA
Motorola 6850 ACIA
1974
Motorola's Asynchronous Communications Interface Adapter, a simple UART widely used for serial ports in 6800/6809 machines.
Reference & documentation
External technical references for programming Motorola 6850 ACIA and for writing emulators.
| Resource | Type | Notes |
|---|---|---|
| Motorola MC6850 ACIA Datasheet (PDF) ↗ | Datasheet | Full official datasheet: registers, timing, electrical specs |
| SWTPC ACIA Hardware Notebook (MC6850) ↗ | Datasheet | Historical ACIA reference sheet with register detail |
| 6850 ACIA chip - CPCWiki ↗ | Memory map | Register map: control, status, TX/RX bit layouts |
| Motorola MC6850 ACIA Datasheet (PDF) ↗ | Pinout | Pin descriptions and package pinout diagrams |
| 6850 UART interfacing code (Arduino) ↗ | Programming | Init sequence, clocking, control-line handling with schematics |
| Adding a serial interface - MC6850 ACIA ↗ | Programming | 6502 init, polling, status-bit driven I/O routines |
| MC6850 Datasheet - full searchable text ↗ | Reference | Plain-text datasheet, all CR/SR bits documented |
| Hatari acia.c - cycle-accurate MC6850 emulation ↗ | Source | Bit-level, cycle-accurate ACIA rewrite from datasheets |
| 6850js - JavaScript ACIA emulator ↗ | Source | Compact JS reference model of TX/RX operation |
| MC6850Tester - hardware ACIA test rig ↗ | Test suite | Pi Pico test sequences validating real 6850 chips |