Here is what I have been working on the last few/several days. Another scrolling gradient but this time it is fully stored in the SD RAM. Double buffering wouldn't be too hard at this point but I will avoid it if I can. A custom DMA controller has priority on the bus and transfers the next line on horizontal sync. A number of tiny issues kept me from calling this done, subtle timing issues caused the image to be shifted right 2 pixels. Fixing some bugs made it appear worse even though it was closer to correct.
My colleague who is also using the OR1200 has been kind enough to keep a record of issues he had with building the toolchain (additional packages needed, using git for the first time, etc). I will be working with him to revamp my earlier post. I will also later be checking in code for this and finally be able to move onto implementing the SDCard.