AOS is a basic operating system for 8-bit Atmel AVR microcontrollers. These microcontrollers use the Harvard architecture, meaning that data cannot be executed as code; due to this, AOS operates by executing programs written in AOS bytecode (ABC).
AOS consists of three main components:
- The AOS Virtual Machine (AVM) which executes ABC.
- The kernel, which configures an AVM environment and manages its resources.
- The shell.abc program which provides a user interface for AOS.
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AOS uses a basic filesystem which is currently stored on the AVR's EEPROM memory. In the future, AOS will support storing the filesystem on external flash instead. EEPROM has a relatively low write lifetime (approximately 100,000 writes), meaning that bugs in AOS' filesystem could instantly and permanently destroy your AVR's EEPROM. Use a simulator where possible!
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Upon booting, AOS loads the file at the beginning of its filesystem and executes it. (This file is called the rootfile.) You can find valid filesystems with rootfiles in the Filesystem dumps folder of this repo. Read the source to find out how files are structured if you'd like to make your own.
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The Tools folder contains a basic ABC assembler written in Ruby. It's very simple and has absolutely no error checking, but if you're careful when writing programs it works well.
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This has only been tested on an ATmega328P. It will probably work on higher- end chips, but is unlikely to work on lower-end ones unless
PAGE_COUNTis reduced due to SRAM requirements.
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