There are a few bits I have yet to figure out:
Need 3.3v as a supply for the LVC gates. certainly other boards (the Pico) convert the USB 5V to 3.3, just need to make room in the board and BOM
You don't need that. Most 74LVC1G__ gates can run on 5V. They're not just 5V- tolerant ; they can ...

While still waiting on some parts for my 6502/z50 Bus project, I've been playing around with a 65816 project on a breadboard. I've been trying out the Arduino Nano and the Raspberry Pi Pico as some sort of system control chip, handling clock/reset/perhaps even decoding with the Pi Pico's flexible ...

I am trying to collect the options (and their pros/cons) for programmable timers in a modern W65C02 based system. For my own system, I am looking to end up with four (4) independent timers, but I am going to try and outline all options.

The most obvious is the 65C22 VIA - which includes two (2) 16 ...

I am thinking about replacing all the discrete logic with a simple GAL or PAL, as it definitely will all fit and help tighten up the bus timings. But I think I'd still need to keep the output latch and input max, unless I went for a CPLD. Still, going from three packages to one for the bus signals ...

So, if I want to support read back, I'll just have to add a '254 and make room for it. A little typo there? I think you mean add a '25 1 . :wink:

[...]

Finally, in your existing schematic I see that two of the input bits to your '251 are unused and tied low. Instead they could be put to work ...

2) Does this Mux actually work the way I'm trying to use it? Almost! But your schematic specifies an 'HC151, and what you really want is an 'HC 2 51 (which features tri-state outputs).


Very good observation! I'm working on a new revision and this is my top priority.

I finally printed out the ...

Updated Render:
Screen Shot 2023-03-05 at 2.28.42 PM.png

3.3K is generally a good value.
Whoops, this version of the schematic didn't even have a value for those control pull-ups! Yes, RN1 should be a net of 7 3.3kOhm resistors.

That would be influenced by how fast you want to run the bus.
I ...

Oops, yes, they are all supposed to be 100nf caps, not 100uf.

I've thought about looking at JLC's SMT assembly service to drop all the caps and resistors on the board, but I was thinking about that as a revision B. I definitely agree a hobbyist is more likely to have a pile of 1/4W resistors that ...

Hi y'all, long time reader and first time poster.

I've been enjoying my breadboard build, and an Apple 1 SBC from eBay, but I want to put copper (and my money) where my mouth is and build out some PCBs. I also own a lot of gear from the RC2014 and "Small Computer Central" ecosystems, and because of ...