Implementing an operating system isn't that different between the main CPU architectures. I think mcpherrinm was just saying that you have to do a lot less work than for x86, for example, in order to get a minimum of functionality.
Unfortunately I don't know of any guides on implementing a toy OS on ARM. The operating systems course I've taken was a decent starting point, but it mostly deals with theory: [0].
There's also a first year ARM architecture course: [1]
Another course I've taken was about ASM programming on ARM, plus programming some simple hardware[2].
I'm not sure how useful are those materials for someone not taking the courses, but they might offer a list of things to look up somewhere else. Wikipedia actually has some good background theory.
Finally, you might look over the ARM port of EDK2[3]. EDK2 is a BSD-licensed implementation of UEFI[4]. It implements a lot of the functionality of a regular operating system, with the notable exception of multithreading. I find the source code of EDK2 to be easier to understand than the source of the Linux kernel. Probably because it is a lot more lightweight. You can run it on BealgeBoard, by the way. I'd say it's alpha quality software at the moment, so you might get some weird bugs.
Disclaimer: I'm a CS student at Manchester University and I work on EDK2.
Unfortunately I don't know of any guides on implementing a toy OS on ARM. The operating systems course I've taken was a decent starting point, but it mostly deals with theory: [0].
There's also a first year ARM architecture course: [1]
Another course I've taken was about ASM programming on ARM, plus programming some simple hardware[2].
I'm not sure how useful are those materials for someone not taking the courses, but they might offer a list of things to look up somewhere else. Wikipedia actually has some good background theory.
Finally, you might look over the ARM port of EDK2[3]. EDK2 is a BSD-licensed implementation of UEFI[4]. It implements a lot of the functionality of a regular operating system, with the notable exception of multithreading. I find the source code of EDK2 to be easier to understand than the source of the Linux kernel. Probably because it is a lot more lightweight. You can run it on BealgeBoard, by the way. I'd say it's alpha quality software at the moment, so you might get some weird bugs.
Disclaimer: I'm a CS student at Manchester University and I work on EDK2.
0: http://www.cs.manchester.ac.uk/ugt/2010/COMP25111/
1: http://www.cs.manchester.ac.uk/ugt/2010/COMP15111/
2: http://www.cs.manchester.ac.uk/ugt/2010/COMP22712/
3: http://sourceforge.net/apps/mediawiki/tianocore/index.php?ti...
4: http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Int...