Hi, I hope I am not violating any posting reguations by asking this question on an Arduino specific forum. Here goes. There are many very attractively priced evaluation boards available form various vendor and suppliers. They normally come with typical, but not necessarily the largest memory of the microcontrollers available within a given family. But they often utilize the same packaging i.e. 100 pins or 144 pins etc. I would perhaps like to take one or more of these eval boards and replace the microprocessor with a replacement that has more internal memory. Say instead of 128K replace it with one that has 512K memory on-chip. Presumably all the pinouts would be the same so that it's a simple swap by desoldering the existing chip and replacing it with a chip sporting much more memory. Obviousy the latter chip would have to be purchased separately. Of course if the pinouts do not remain the same there would need to b some intermediate PCB board to translate the pins back to the original layout. But that's a complication I hope designers and the manufacturing process would avoid. So is this a practical way to get more memory from the same microcontroller family eval boards, perhaps even including some Arduino SMD boards? I look forward to reading all your feedback.
I dunno. desoldering and replacing a large fine-pitch SMT part is not going to be very easy...
As for the Arduino, I think all the existing boards are using the "biggest" CPU with that particular pinout. There is no 28-pin AVR with more memory than the 328p, nor a 100pin chip with more memory than the 2560. (though I WAS somewhat disappointed that the new "xmega" chips were not pin-compatible with the 1280/2560. But that's Atmel's fault!)
"nor a 100pin chip with more memory than the 2560" altho the 1284 does have more SRAM, 16K vs 8K on the 2560. Can get it in a DIP package too. The 2560 does make it easy to add more external RAM tho. But its also ~$8 more/chip too.
Norm-Folkers: There are many very attractively priced evaluation boards available form various vendor and suppliers.
I don't think a specific answer can be given to such a generic question.
This is the same question you asked: "If I buy a random board from a random vendor can I makes changes to it to increase its memory?"
The only proper answer is: "it depends..." Depends on the board, the architecture of the processor, the actual processor on the board, etc.
Ask about specific boards / processors if you want a real answer.
You might want to have a lok at the Atmel STK-600 board. Its a generic board with lots of headers, 8 LEDs, 8 buttons, RS-232, USB, CAN... It works with all of Atmel's processors. To use you, you also get a card specific to the form factor of the uC, for example, a card that accepts a TQFP-44 uC. They you get a routing card that is specific to the uC. They you mount the socket card on to the routing card and the routing card on to the STK-600 and you have one cool prototyping hardware system.