Are the Arduino family of Chips Pin compatible?

Are the Arduino family of Chips Pin compatible? I mean, could you simply unplug one chip and upgrade to the better one if you purchased the lowend board first? Rightnow , I have the Mega. I wanted to purchase a few more boards. But, what if they are not as fast as I want them, do I have to buy all new boards or just the chips?

Are the Arduino family of Chips Pin compatible?

In short no. Some have the same pin out as other but the mega is a quad flat package and the 168 and 328 are DIL (these are the same)

See the data sheet

Well I have interchanged the following 28 pin DIP AVR chips in a Arduino clone board, meg8, mega168, mega328. All worked well and I was able to reburn bootloaders for all three using a USBtiny programmer and the ISP connection on the Arduino board using AVRDUDE. So either blank chips or chips with pre-burned arduino bootloaders can work fine. Just be sure to change the board selection in the Arduino IDE before compiling or downloading a new sketch.

Lefty

As far as I am aware these all run at 16MHz anyway so there will be no speed advantage.

Thanks for the info.