Here are some links:
ProgrammersHeavenAminetInformation about RISCYou´ll need the information about RISC architecture, if you wanna learn PowerPC assembler. Actually i´ll guess you´ll learn it much easier if you read some documentation about RISC first, as PowerPC is a RISC architecture.
Anyhows, THE book for learning about RISC is "Computer Organization and Design: The Hardware/Software Interface" by Hennesey & Patterson. If you really wanna learn RISC programming, this book gives you all the informations about pipelining, caches, etc, and has good examples in MIPS code (which of course, also is RISC).
