There are 2 repositories under atari800 topic.
Mad Pascal Compiler for 6502 (Atari XE/XL, C64, C4Plus, Neo6502)
Various reverse engineered source code
This is a mashup between BlocklyVN32X and 8Bit-Unity. It allows you to make Visual Novels for classic 8bit computers and consoles, using a visual scripting language.
Psychedelia/Colourspace by Jeff Minter
Atari 8 bit Text Window and FujiNet Library in C (CC65)
Code that runs the Atari 8-bit Twitter bot at https://twitter.com/Atari8BitBot
Firmware for ESP8266 to emulated D: and R: for PLATOTerm64 on Atari 8-bit
Atari Inform Interpreter
Scramble-like game on Atari 800 XL in Action! programming language.
A small font originally designed for an Atari 800 terminal emulator.
A clone of Arkanoid for Atari XL/XE written in CC65
The most complete collection of Atari computer and console emulators in a single scoop bucket
Attack of the Mutant Camels (1983) by Jeff Minter
Atari 8 bit Text Window Library in Pascal (Mad-Pascal)
RetroLoad.com is a web application for converting tape archive files of historical computers into sound.
2020: Atari 800 emulation using a Teensy 4.0, 3.6 or 4.1 with a standard USB keyboard for input. This is a simplified expansion of Jean-Marc Harvengt's Multi CompUter Machine Emulator M.CU.M.E
Servicio Docker para compilar juegos escritos en C y Assembly para Atari y NES utilizando Alpine Linux. Suportados: Atari 2600, 5200, 7800, lynx e NES
My (archival) project of universal power supply for 8-bit computers (atari and commodore 64). There'll be a new version soon.
Atari 8-bit Rom Image File Explorer based upon ATR Image Explorer
A horizontal Shoot'em Up Game written for the Atari 8bit computer.