An Arduino-based floppy drive emulator for the Atari 8 bit computers.
This small Arduino build emulates an Atari 1050 floppy drive to connect to an original Atari 8-bit computer. The program is compatible with most Arduino boards. And for boards based on the Atmega32u4 it also provides various log messages on the serial monitor to help debugging (mainly for my own use).
For a breadboard setup like my development device, you will need two push buttons, two 7-digit LEDs and one SDCard socket (with built-in or separate level shifters) and some wires and resistors. The connectivity is pretty standard and you will find the details as comments in the source code.
Emulated floppies on SDcard
The floppy drive emulator needs an SDcard containing .ats files for each individual floppy disk. Because there is no elaborated user-interface on the device, the naming and location of the files need to follow a fixed system: The files are searched for in a directory ATARI/ on the root of the SDcard. Every disk file must be named nn_Anything.ats with two leading digits that correspond to the numeric display on the device and the mandatory '_' character. Alternatively you can also have a folder named nn_Anything with individual files inside. Such a folder will be emulated as an read-only enhanced density floppy containing these files.
Currently only a very basic support for single density (720 sectors) and enhanced density (1040 sectors) floppies is provided without special functions for any third-party devices.