[pwaring]

I'm not aware of a good free introduction to ARM assembly, but you could check out the reading lists from these courses:

http://studentnet.cs.manchester.ac.uk/ugt/COMP15111/syllabus... http://studentnet.cs.manchester.ac.uk/ugt/COMP22712/syllabus...

Despite its age, ARM System-on-Chip Architecture (Steve Furber) is still a good introduction to the processor and assembly (I'm re-reading it at the moment). ARM Assembly Language - an Introduction (J.R. Gibson) is worth reading if you want to learn ARM assembly.

The materials page for COMP22712 also has some interesting resources, including the lab manuals and a small ARM assembler written in C (source is also on GitHub: https://github.com/uomcs/aasm). Unfortunately COMP15111 is now hosted on Blackboard so you can only get at the materials if you're a current student enrolled on the course.

(I've been an undergrad, postgrad and staff in CS at Manchester, so I'm familiar with the courses - other universities may have similar resources with fewer access restrictions).