This is COLE-1, my first 6502-based SBC. The name doesn't stand for anything; I just needed a name and decided to name it after my late cat.

Specs:

WD65C02-14, originally clocked at 2 MHz but currently running stable at 4 MHz
WD65C22S VIA, running a jiffy timer and both ports brought out to headers for future expansion
MC68B50 ACIA connected to TTL serial running at 115.2 kbps
62256-70 32K RAM
AT28C256-12 32K EEPROM (30K usable owning to taking a chunk for I/O space)
MAX1232 for reset circuit and watchdog timer (though i ended up disabling the watchdog by clocking it from Phi2; I wanted my VIA pin back)

All of the discrete components except for a BAT85 diode are 0805 surface mount components on the back of the board.

I went with the 6850s because I have a dozen or so of them in my personal stock, from when I was buying up parts with plans to build one of each of Grant Searle's SBCs. The MAX1232 was kinda overkill too once I disabled the watchdog, but I already had them so I went with it.

The schematic and PCB layout were done in KiCad. It's a 100x100mm 4 layer board, fabbed by PCBWay. In retrospect I probably could've squeezed all this onto two layers, but I wanted the ground plane, and I also was kinda anxious to try a four layer design.

The funky contraption in the lower left is because I messed up doing my layout, and didn't realize that I'd picked a 10mm wide footprint for the ACIA instead of the normal 15mm footprint. Rather than toss out otherwise perfectly good boards I rigged up a converter with some single-row headers and double-sided perf board. It's ugly, but it works, and needless to say I will not be making that mistake again! I should've printed out the layout and did a test fitting, but my ink jet printer is still disconnected to make room for my 3D printer.

I had a lot of fun designing and building this; I've wanted to build my own custom computer since I was a young kid. I learned a great deal along the way, largely thanks to all the posts by everyone on this forum. Going forward I am going to be experimenting with adding video and sound to this SBC, and also start doing some preliminary work on COLE-2, which will be 65816-based.

I'm intrigued by the parts-on-both-sides thing (even though it looks like you had plenty of room on the top).

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Preference, more or less. No real reason.

Nice project, and welcome!

Very nice. I'd like to see the other side of the board.

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Cat; the other white meat.

I don't have a pic of the final, finished assembly but here's one I took after I got all the surface mount devices installed. Solder flux isn't cleaned up yet so it looks a bit nasty (and I'm still not very practiced at the surface mount soldering...)

At the top is all the pull up/pull down resistors for the '02, and the rest are just bypass caps. Nothing fancy.

100x100mm seems to fill up pretty quickly, but it's often a good pricepoint - I imagine that's why you chose it.

JLCPCB will produce 10 boards at 100x100mm (2 layer) for only $2. I swear they are not paying me to promote them but maybe they should. lol


https://jlcpcb.com

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Cat; the other white meat.

There's usually quite a premium for 4 layers though - presently that's showing as a special offer price of $30. Still very affordable.

Yeah, the only way you get the $2 deal is the board must be 100x100mm (or less) and 2 layers with 10 boards max.

I went over that at a bit but still got 10 boards for under $25.

You also pay more for solder mask colors other than green.

So, for prototypes, it's hard to beat their price. They do put their makers-mark on the boards too but you can pay extra to not do that.

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Cat; the other white meat.

Yup, that's exactly why. Seems like everybody's cheap deals are for 5x5 cm or 10x10 cm boards. For PCBWay it was $50 for five boards with four layers (and I just noticed last night that they actually sent me six). They're more expensive than say DirtyPCBs, but on the flip side I had the boards in my hands just seven days after submitting my order, and their quality seems excellent (this is my second time ordering through them).

Now if I just hadn't messed up my order and picked green instead of black like I had intended.

I think I'm seriously the only person that still prefers green over all other colors. Red would be a distant second. There is just something nostalgic and awesome about that green mask and white lettering.

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Cat; the other white meat.

I have to admit the PCBWay green is kinda nice. It's more of an emerald green than the traditional PCB green. I still think a black solder mask with gold finish is sexy as hell though.