This is an improved version of the RC6502 PIA communicator firmware for an Arduino Nano. It is based on the original Arduino Sketch provided with the RC6502. I have replaced the Arduino serial library with buffered interrupt-based serial communications routines and removed all the unnecessary communication delays.

This firmware is usually able to accept 40-column hex input at full speed, but it still drops characters with wider hex dumps because the Arduino doesn't have hardware flow control. However, using TeraTerm with a 20 ms delay between lines, it can reliably load hex data up to 97 columns wide. With the 20ms per-line delay, the entire 20KB of hex data for Fig Forth, which is in 97-column hex format, loads reliably in under 10 seconds.

This code is compiled with the provided Makefile using avr-libc and avr-gcc and flashed using avrdude. The Arduino IDE is not used.

Replace COM9 with your serial port number:

avrdude -pm328p -carduino -PCOM9 -Uflash:w:"pia.hex":i

forked from J.B. Langston's jblang/pia_communicator

pia.c is based on the original RC6502 pia_communicator.ino sketch by tebl, and released under the GPLv3 license.

uart.h and uart.c come from the FatFs AVR example project. Copyright (C) 2016 ChaN.

The iox.h, iox.c, spi.h, and spi.c come from jblang/z80ctrl