Ah, the brave old 6502...

A project log for OMEN Bravo

As-easy-as-possible, but still expandable single board computer with 65C02 CPU.

Martin MalyMartin Maly 09/04/2018 at 20:310 Comments

It seems to be totally simple, but this was my first 6502 construction I ever designed.

So I have made a design, have prepared a PCB, the last few wires by autorouter (keep it in mind!) and have sent to fab.

A few days ago I have connected the whole design. And then: nothing. No single tick. It was very strange... When I have removed the 7400 (RD/WR and address decoder), the oscillator worked. 7400 back, frequency: 0.

Totally bad dream. Later I have found the one line from CPU is routed directly through the Xtal, just between its two pins. I have cursed myself. Twice.

The second PCB version works on the first attempt. So design was right. My mistake was the autorouting. All other PCBs are now manually routered until the last via...

(Don't worry, the piece I am selling on Tindie is the Issue 2)