The WDC 65C265 is a sweet microprocessor, unfortunately the MENSCH breakout board sold by WDC lacks the chip select lines! I was able to add a static RAM, but without the chip select lines you are really limited in what you can. WDC sells the W65C265SXB, but it lacks a 65c22 which is what I want to pair the 65C256 with. I might be able to cobble together an address decoder to memory map a 65c22 and static RAM with my MENSCH. But that seems like a lot of unneeded work given that the 65C256 has an address decoder built into it.

In the 65816 Pseudo-SoC thread I expressed a wish that someone would design a PCB for the 65C256 that was more useful. While I have built many prototype circuits using a variety of techniques, I have never designed a PCB. But I might as well give it a try and finally learn how to do it.

In reading the schematics for the WDC boards, I think I can cut down on the parts count by using a DS1233 5V EconoReset, and possibly TTL oscillators instead of the crystals and loading capacitors. The primary IC's would be a 65C265, a static RAM, an EEPROM, and a 65c22. I would use an FTDI breakout board to communicate with my PC.

But if I were to try this, what PCB design software would be good to use? My laptop is a Windows machine.

i use KiCad for designing the Schematic/PCB and Freerouting to do the routing of the PCB, mainly cause i'm lazy and autorouters are pretty good nowadays.
though as a tip, kicad has the ability to export schematics as monochrome PDFs, which i recommend doing over taking screenshots. as PDFs have infinite resolution and monochrome is better for colorblind people.

also instead of a full breakout board you could directly use a parallel to USB serial chip like the FT245R or it's cheaper brethren, the FT240X.
of course that means soldering an SMT component, but it's not that bad if you just have a regular soldering iron and one of those manual desoldering pumps.
you basically just flood all the pins with solder, heat the blob up with the iron, and then suck the excess away with the pump. (i personally find this way better than using de-soldering wick, or maybe mine is just low quality).
anyways using a seperate chip instead of the built-in UART is definitely better as that gives you more freedom for the clock source of the chip.
on the same note, i would keep the crystal oscillator and put it in a socket, so you can swap it out to test different clock speeds.

anyways good luck on this journey! seems like a fun project. i might attempt something like this myself

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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?

I, too, recommend Kicad. Its free, its good, what's not to like?

Plus, you can take advantage of my 6502 Kicad Library for all your WDC chip schematic needs.

_________________
Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

Gone or not I still have a perpetual hobbyist and small board license and version 7 for Linux. Not that I have much remaining on Eagle, but I do have some stuff and it annoyed the hell out of me when Autodesk bought it and decided rental was good for me.

These days I like very much Kicad, and work just licensed me for Altium; I'm not sure how much I take to it yet but I won't be using it for hobby stuff.

Personally, I'm not a huge fan of autorouters; I prefer to lay out by hand.

Neil

@All, thanks for the replies. It sounds like Kicad is the way to go. I will try it and post an update for further feedback and questions.

@Alarm Siren, the 6502 Kicad library sounds incredibly helpful.

Also throwing my hat in the Kicad ring. And mangling a metaphor.

Specifically I like Kicad 6. It's a huge step up from the old Kicad 5. However the auto-router has been completely removed in version 6 - and I think that's fine because it was kinda dated and iffy anyway. I'm not a fan of auto-routers either. One day I hope there will be a competent one but we're not there yet. And routing isn't hard. I route horizontal traces on the front and vertical traces on the back. It's a style I find I can do quickly and mechanically. I find the hard part is in placing components to allow for easy routing.

To put it in perspective that PCB probably took about four hours from start to finish. I doubt that's impressive for a professional (well, I know it's not from having watched YouTube videos) but I think that's a good time for a hobbyist. And only about a third of that time was trace routing. The majority was placing components; a bit of board setup (and clean up); and footprint fixing. I'll happily spend an entire weekend on a coding problem - an afternoon on a PCB seems okay. And I have something tangible at the end.

Designing the schematic on the other hand... that takes me ages. And is something I whinge about quite often.

I'm also doing a bit of a completely unrelated experiment to see if the colours I've picked in the image are visible to everyone without having to include a black and white version. According to a vision simulator they should be but ... I'm not sure.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

I have only ever used an auto-router once, and that was as part of my university course when we were specifically being taught how to use an auto-router. I found it such a pain to set up and actually use, it would be quicker to do the routing manually. I've never gone back.


I agree, and this is also the style I try to go for - though depending how dense the design is it can be a challenge to keep it strictly H/V per side.


KiCad 6-7 does support an auto-router as an optional extra, you can download it from the Package & Content Manager (bottom button on the main menu). If you've never looked in the PCM before, which wouldn't surprise me as I only recently discovered it myself, I'd recommend having a gander - there's some good stuff in there.

_________________
Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

I pretty much exclusively use an autorouter for my PCBs (with some manual tidying up afterwards). Exception being really simple boards like breakout boards.

What kind of autorouter did you use that took wo much effort to setup/use?
For me the process is just:

• export spectra session from Kicad
• import it into freerouting
• optionally adjust settings like preferred trace direction (default settings are usually good enough though)
• click "autorouter" and wait for it to finish
• export the session from freerouting
• and finally import it back into Kicad

I think freerouting does exist as a plugin for Kicad, which would do most of those steps automatically so it becomes even simpler to use.

Obviously if someone uses an autorouter or not is a personal choice.
No one's gonna force anyone to use an autorouter and no one's gonna be ridiculed for using one either.

Though I would recommend you to start with routing PCBs manually, to learn it and get a feeling for it.

.

On another note, you could put a few SPI-10 connectors on the board to allow for simple SPI based modules to be plugged in.
Obviously the actual SPI interface would have to be done in software through some GPIO pins, but it would still be useful to have a few connectors like that available.

I dunno what it was called, its whatever came with Siemens PADS Layout, which was the tool in use by the university at the time - they subsequently switched to EAGLE against my advice (I tried to convince them to use KiCad).

to be fair, part of the problem might have been that they had intentionally disabled it so that students wouldn't use it normally, so we had to jump through hoops to re-enable it. Nevertheless I do not remember it being worth the effort, and the result was decidedly subpar anyway.

_________________
Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

Takes me back to the days of red and blue pencils on tracing paper to do the routing, then stick-down black tape to lay the traces, then photoreduce, and then hopefully you didn't have to do it again.

(Eee, when I were a lad if you wanted autorouting first you had to design the computer to do it with, and then write the code... red and blue pencils were quicker!)

Neil

_________________
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?

I started with manual routing in early 1980's with Racal Redac's Maxi workstation (expensive! >$100K) but once I had decent autorouter such as Cooper & Chyan router, I don't do manual routing anymore. The schematic/PCB tools (WinDraft & WinBoard by Ivex) I currently use were inexpensive tool for small business but does have Specctra router (aka Cooper Chyan). Ivex went out of business in early 2000's and I haven't updated it for 20 years but I still use it to design every boards and autoroute pretty much all of them. The software are buggy but not updating for 20 years means I know just about every bugs and how to work around them. For through-hole components on 100mmX100mm board and JLCPCB design rules, the Specctra router can 100% complete in 2 layer even with components placed shoulder-to-shoulder. Here are a couple examples.
Bill