[klodolph]

I'll step in and say that the Atmel AVR is damn awesome processor, it's just that it's hooked up to on-chip peripherals and the address/data bus is completely internal. This means that if you want to connect something to an Atmel AVR, it will likely be over some serial protocol, like SPI, I2C, or UART.

This is what you want, like, 99.9% of the time.

The 6502 just puts its address and data bus on pins, and you can make the memory map for your computer however you want, as long as you are willing to wire up the logic. There's no privilege for on-chip resources... everything is off-chip and completely equal. With the AVR, the resources (RAM, flash, peripherals) are completely fixed but much, much faster. There are a ton of chips you can buy with SPI / I2C interfaces if you want the AVR to do something interesting, and you drive them with the on-chip peripherals. The on-chip peripherals get to sit in memory somewhere, but the external ICs don't. With the 6502, you put things in memory somewhere, figure out a way to decode addresses on the bus, and use a parallel interface for everything.