Day 2 with the v0.1 Board
Soooo......
Already noticing some issues with my board design.
But that's why it's called v 0.1.
OK, so let me start with this, the USB is purely for power. That's all it does.
Going around the board, you will see an unpopulated C1.... because I designed the debounce for the reset button wrong. Nothing worked, then I took it out and realized that I had it in the wrong place in my diagram to do what I wanted it to, but taking it out wouldn't cause any bigger problems.
Next are the 6502, ROM, and RAM, from left to right. Below the memory modules is the 6522, and to it's left is the 74LS00 Quad Dual Input NAND gate. Under my hand is a 555 to create the clock and it's pot for controlling the speed.
Finally, on the bottom is the LCD and t he pot to control it's contrast.
I added headers for the 6502's bus (16 pins for address, 8 for data), and the 6522's A and B Ports.
First huge, glaring, immediate problem:
No LED for the clock to see how fast the thing is going.
Follow that with:
Bad design of the debounce circuit for the reset button.
I need to pick better models for the resistor and capacitors, so they fit better.
Next Steps:
Update the ROM with the code that checks for the display to be ready to continue. That means I can finally move ahead in the Ben Eater series. As you can see in the picture, it's not writing to the screen, but he noticed that was because it was running too fast. I'm not sure how fast I'm moving right now, but I'll get the oscilloscope out check when I get a chance.
I need to update the wiring diagram to use different pins on the switch. I got it 90 degrees off on the model, and the wiring diagram doesn't show which pairs of pins are connected without the button being pushed. 😡
The switch does fit the holes without mangling it, but alas, I did it wrong. Live and learn.