OMEN Bravo

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Issue 3 added the VIA chip - Versatile Interface Adapter R6522. It provides two serial ports, two 16bits counters / timers and a shift register for parallel-to-serial conversion and vice versa.

Unfortunatelly, Issue 3 has an error - ground was not connected together and there were missing place for the resonant capacitor and load, so some CPUs won't work. You can solder one wire and a two parts directly to the PCB, but it is not a solution, so I designed an Issue 4 PCB with all of those bugs fixed.

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)