[quote]So to understand the DAL API when the meaning of a call is not clear apparent on needs to read the appropriate place in the TRM, even though the TRM does appear not mention anything in the DAL by name?[/quote]
Think of the TRM as a companion document. It will not mention anything in the DAL API because the TRM describes the HW, not the abstraction layer above it. The StarterWare UG also has a lot of useful information about the APIs as well. There is a PDF in the StarterWare Docs folder and is online here: http://processors.wiki.ti.com/index.php/StarterWare_02.00.01.01_User_Guide
[quote]If, say, I look at RASTER.C I find it has 42 functions, but if I look at the sum total of the StarterWare examples (that I downloaded) I find that only 20 of them are 'exampled'. Does this mean the function of the others is considered obvious, or what?[/quote]
Not necessarily but each one contains a short description which was lifted directly from the comments in source code (this is a Doxygen-generated document). The source is provided as open-source so that is an API is questionable in it's usage, the source can be reviewed, along with the TRM, to determine exactly what it does.
[quote]Understand, just pulling at an example. So does *nix use the DAL API to build on, or does it start from scratch?[/quote]
*nix includes device abstraction but the usage is very different.
[quote]Can you hazard a guess as to how long it takes someone to become 'proficient' and then 'expert' at the DAL API? Is there formal learning available?[/quote]
Sorry, but that's entirely subjective. We don't have formal training for StarterWare but there is a section of our Processors Wiki dedicated to StarterWare; http://processors.wiki.ti.com/index.php/StarterWare