Hi,
Thanks to everyone that took the time to reply, I learned a lot and I did eventually get it all connected correctly. But... as mentioned, there was not enough RAM. I'll look into small micro controllers with more RAM and carry on. 
Cheers!
1284P, 16K SRAM, twice that of the Mega2560 even.
Easy to add to the IDE also.
Hi
I am looking to do something similar
I have a mega 2560 and a 3 inch TFT LED display 480 x 320 pixels landscape view
What I am looking to do is to create a grid of five wide by three high and display images in each square
The images would be located on the flashcard on the SD card
And the image would be displayed when one of the pins has got a high signal on it
So for example if pin one is high image one will display or a pin two and four are high then images two and four will display
Eachimage will each have its own place on the grid and will be displayed in the same place each time
The state of each pin can change randomly so the pins need to be monitored all the time so that if the pin state changes the different image will be displayed
I haven’t tried to do anything like this before so would appreciate anyone that can provide bullet points of what I need to do start to finish and or any examples of projects that have used a similar theory
Thanks
CC