Computers have no sense of humor. One single connection made improperly can be fatal to it working.

Do you have this built up on a solderless breadboard?

Have you measured the Vcc at each device?

What are you doing with A15 on the EEPROM?

How do you have PUTTY set up?

Also, Grant is using the ...

Firstly, try swaping TXD and RXD, just in case you have them around the wrong way. Also check the baud rate, the source code should tell you what this is set to, it'll also depend on the clock running correctly. Check baud, parity, stop bits and confirm that putty has the same values as the source ...

Hello, I'm new to working with the 6502 and I have a pretty shallow understanding of electrical engineering. I wanted to take the plunge because I figured that it would be a good (but apparently frustrating!) way to learn.

I based my design very heavily on Grant Searle's simple 6502. It looks like ...