If you generate the CPU clock from the Arduino, then timing is not a problem since you can synchronize the memory simulation with the generated clock within the Arduino code. You won't break speed records but it's perfectly fine for experimentation - I've done this, but using an Arduino Mega (which has plenty of pins to cover the full 16-bit address space if needed.)

A small step further is to support in-circuit programming of an EEPROM using the Arduino, which if given control of the 65C02 BE bus enable line, can take the CPU off the bus during the programming operation. I have this working, but haven't used it much since I currently find it more convenient during code development to upload directly into RAM from a PC using a USB to "TTL" converter, with fixed loader software in EEPROM.

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

Man, breadboards get nasty real fast. I think I'll stick to my trusty ol' soldering station and a roll of wrapping wire. And it looks way cleaner!

I'm going to put all buses at the bottom side, and use top side only for power rails & glue logic wiring.

Also reserving some space for EEPROM (rightmost socket), SID (bottom-right), & VIA (bottom). I'll mount 2004 LCD separately, probably in a daughterboard fashion. But I really want to keep all chips exposed, it's so satisfying to simply be able to observe them.

I'm also planning to add a bunch of dual 7-segment indicators with GAL-based hexadecimal decoders to be able to observe what's going on at the data & address lines.

_________________
/Andrew

deck65 - 6502 slab with screen and keyboard | ПК-88 - SBC based on KM1810VM88 (Ukrainian i8088 clone) | leo80 - simple Z80 SBC
nice65 - 6502 assembly linter | My parts, footprints & 3D models for KiCad/FreeCAD

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

Just finished adding them, photo was taken before I've added them

_________________
/Andrew

deck65 - 6502 slab with screen and keyboard | ПК-88 - SBC based on KM1810VM88 (Ukrainian i8088 clone) | leo80 - simple Z80 SBC
nice65 - 6502 assembly linter | My parts, footprints & 3D models for KiCad/FreeCAD

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

In addition to BDD's construction notes...

the ZIF socket for the EEPROM. I generally use a machine-tooled socket on the board and plug the ZIF socket into it. You get the benefit of easy chip removal/insertion during development and can reuse the ZIF socket on later projects.

_________________
Regards, KM
https://github.com/floobydust

As a practical leg-defensive approach: I use a chunky zip socket on the programmer, but a standard socket on the board (apart from anything else, for space reasons). But I keep a sacrificial socket on the eeprom; neither the programmer nor the board socket object and it means the eeprom pins don't get accidentally bent with all the insertion and removal.

Neil

Using machine-tooled sockets with a ZIF socket is actually a cool idea, I didn't think about it. It will definitely reduce the footprint on the board also make it easier to squeeze extra caps/wires underneath. I'll try it!

In the meantime, I've updated my schematic to pass all ERC checks and came up with a version that I'll attempt to make a PCB of.

My 4x W65C02S have been shipped now, so I'll have them really soon - I hope! I've decided to include 2004 LCD & 6522 VIA in my "beta" PCB prototype, and I'll still use my perfboard for testing the basics - 6502+RAM+ROM.

_________________
/Andrew

deck65 - 6502 slab with screen and keyboard | ПК-88 - SBC based on KM1810VM88 (Ukrainian i8088 clone) | leo80 - simple Z80 SBC
nice65 - 6502 assembly linter | My parts, footprints & 3D models for KiCad/FreeCAD

Just once thing I once fell for. The most standard LCD text displays (All based on the Hitachi HD44780) have an active high Enable line. They are also quite slow, they will probably struggle at 1Mhz. In my SBC (viewtopic.php?f=4&t=5907), I bitbang the LCD interface with a VIA so I can run the CPU as fast as I need to.

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

So I spent a ridiculous amount of time trying to route the PCB manually, and I eventually gave up and used DipTrace to auto-route things for me, because what the hell, it's just a prototype. (I think this project will actually never leave "prototype" stage, haha).
Also I've managed to squeeze everything within 10*10 cm footprint! That will save me some bucks.

My friend offered me some help with some improvements (including teardrops & copper pours), so that's what we'll try to do before printing.

Anyway, I know auto-routing is not perfect, there might be crosstalk and stuff, but I think it *should* work for my 1MHz device. I'll still be making another one with SID, EEPROM, & ACIA some time in the future - but for now, I just can't wait to order my bare-minimum first PCB ever!

_________________
/Andrew

deck65 - 6502 slab with screen and keyboard | ПК-88 - SBC based on KM1810VM88 (Ukrainian i8088 clone) | leo80 - simple Z80 SBC
nice65 - 6502 assembly linter | My parts, footprints & 3D models for KiCad/FreeCAD

Looks like a good result to me. Each year that passes, I'd imagine autorouters get just a little bit better.

_________________
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?

It's not bad! And I've created a monochrome version of the image.


I notice the headers attaching to VIA Port A and Port B are only 10 pins each. I'd suggest 14 or even 16 pins each so you can connect a ribbon cable to an external device and supply the device with power, ground and perhaps even an extra signal or two.

I guess you're anxious to proceed. But if you decide to do another pass on the design, you could save some space by using a smaller oscillator, if available. Alternatively, the oscillator could be relocated. Right now the width of the board (from west to east) is consumed by...

• oscillator, CPU, RAM, ROM, VIA. Instead, you could try...
  
• ROM, RAM, CPU, VIA

The ROM (in its ZIF socket) is comparatively bulky, which is one reason I think it might do well at the edge of the board. Half of that extra width can hang over the edge! Oh, and I was thinking the CPU would be oriented with pin 1 toward the north, whereas the RAM, ROM and VIA would have pin 1 toward the south. This will tend to untangle some of the bus lines, but maybe with the auto-router you won't worry about that. Still, it'd be interesting to see what it would produce if you start by arranging the chips as I suggest.

Whether you do or don't reorient the chips, I would still consider moving the oscillator. With the extra width that's freed up, maybe those two headers for Port A and Port B could snuggle up broadside right next to the VIA instead of being pushed off the end. Just an idea... Good luck with the project, and have fun!

ps- and as Garth says, you needn't bother with the pour -- it is not a ground plane.

-- Jeff

_________________
In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html