Here you can find a open source and free programmer for Atmel's 8051 well known MCU family. This includes the linux tool (at5tool) and some other tools (in the future) needed to make a complete development environment for the AT89xxx, both with SDCC (GNU C). Theese tools can be used only on Linux at this moment.

Here is the Project summary page on SourceForge http://www.sourceforge.net/projects/at51programmer and the CVS repository.

at51programmer is a complete project for building the whole of device programmer. It includes open source firmware, open source software and open hardware. Here you can read more about the GNU philosophy about the free software and OSI's open source understanding. All sources and documents of this project are free software, distributed under the terms of GNU General Public License version 2, june 1991.

You can download the latest sources from CVS. Also, you can download it from the Download area.