looks good – a lot more risers than I would have thought – are these JTAG like things for debug that won’t be on the final board or are they all for GPIO and I2C etc..? I see there is a reset button, what are the other two buttons for? I assume the total memory = 80M is just a preliminary thing until you get the real memory map worked out?
Yes, there are risers for peripherals (camera, LCD) that won’t be on the final board as people won’t be able to access them anyway (no end user access to the GPU). They are there for testing and development purposes. Some of the signals may go out to GPIO so you can attach things though, esp. camera. The memory is shared between the GPU and the CPU so Linux won’t have access to the entire 128/256 memory map, the GPU can use quite a bit depending on what you are using it for.