I just use WW wire for ground and Vcc. However, my next workbench computer (which has been years in coming), if it's WW at all instead of being on a custom PCB, will use WW board with at least one if not two planes, as shown in the third picture at http://wilsonminesco.com/6502primer/construction.html . I have plenty of that stuff sitting here. But if you can't do that, put the bypass capacitor right down to the board and solder it at the base of the pin, using as little of the pin length as possible, and don't let the solder creep up the pin; because you'll want to put the power and ground wires as close to the base as possible too.

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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?

The manufacturer will describe a low ESR electrolytic with that term or with "low impedance."


That would work, but is indeed pricey. Take a look at this one, which is a 1000 µF/10 volt low ESR part. It's one that I regularly use for bypassing purposes in both digital and analog projects. Farnell indicates that they have plenty of local stock and at £0.34, is comparable to the $0.60 US price at Mouser.

Regarding the voltage, electrolytics should be operated close to the rated voltage if practicable. In some cases, operating the capacitor at too low a voltage may result in it not actually producing the rated capacitance. For bypassing purposes in a 5 volt circuit it's best to stay in the 7.5 to 10 volt range if possible.

On the other hand, MLCC capacitors used in bypassing service should have a relatively high voltage rating, due to the behavior of these types when subjected to high amplitude spikes. The AVX part that I mentioned in an earlier post is a 50 volt capacitor and is inexpensive, but may not be readily available on your side of the pond. This item at Farnell is an equivalent part in all respects and is reasonable in price. Farnell shows local stock on it as well.

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

Ahh ok. I was uing the ESR rating listed for the caps in Farnell's capacitor listing rather than looking at the datasheets. No wonder I could only find expensive ones.

BTW, here's my currently planned layout. I'm going to move the SRAM down by a row to give me more room to remove it if needed - something that I didn't consider in my last design (arrgh!).
I've used standard DIL IC sockets as position markers just to make life easier .
Latch#2 is optional at the moment and may not go into the design. if so, then latch #1 will be moved into its place. I missed out the reset monitor so will probably put that in just above Latch#1.



Here's the circuit diagram. It's in beta, though.

Capacitor C8 is unnecessary unless the lead length from your DC source to the regulator is more than about 18 inches, but doesn't hurt. Also, you might want to consider rigging up something to blip /NMI via a push button. In your firmware, you can intercept the NMI to break a stuck program by vectoring into the M/L monitor. I did this in my POC unit using a Maxim DS1813 to debounce the push button. It's gotten plenty of use and avoids having to hard reset when I goof up a program and the MPU ends up chasing its tail.

Looking at your components, I'm of the opinion your circuit will top out at 8 MHz. The EEPROM will be the slowest device in your system, but you could wait-state it and then 10 MHz may be possible if your wiring is tight and direct.

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

Close : With that EEPROM in my previous project I managed to get to 10MHz. It's actually Winbond's W27C512-45Z, so runs at 45ns which is quicker than the SRAM.
Actually, as I'm replacing the 70ns Toshiba 32KB SRAM with the Alliance 55ns one then I might just be able to squeeze in to 12MHz range. Here's hoping!

[edit] Thinking on it, how do you over clock a W65C02? Is it simply bump up PHI2 until you get no display, or can you start uping voltages, etc.? Obviously, the 6502 isn the only part in the system, so I accept that other parts must eb able to cope. Any hints and tips?

"Overclocking" the 65C02 is a matter of running it at maximum continuous rated voltage (5.25) and ramping up Ø2. Officially, the W65C02S tops out at 14 MHz at 5 volts. However, if one extrapolates the Fmax vs. Vdd curve on page 24 of the data sheet, operation beyond 20 MHz is implied, although you would be on the device's ragged edge.

I can't vouch for the 65C02 at 20+ MHz, but I can tell you that the CMD SuperCPU cartridge for the Commodore 64 was run at 20 MHz with a 65C816 in it. That device also used a CPLD for glue logic. The GALs in your design are comparable to the CPLD in pin-to-pin prop time. So give it a try. The worst that can happen is it won't run.

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

Surely, overclocking includes going beyond spec: you'd exceed the specified maximum voltage to see what happened. Sure, you'd damage some parts, otherwise you wouldn't know how high to go, but it's a thrill-seekers' game. (You'd also normally cool the part, because performance falls off with temperature.)

The worst that could happen, arguably, is that the result would be unreliable, even after you've backed off: there's nothing so useless as a computer which doesn't compute. (Actually, the worst that could happen might involve a house fire...)

Let's just hope that the circuit breaker trips or the fuse blows when he cranks up the clock.

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

It's rented so that's fine .

I've now bankrupted myself by ordering the parts, so here goes. The thing that gets me is how much you end up spending on the WW sockets.
So far...

3x 40 pin sockets (CPU, 2xVIA)
1x 40 pin socket chopped down to 32 pin (SRAM)
1x 28 pin socket (EEPROM)
2x 14 pin sockets (Power hub, Crystal oscillator)
4x 12 pin SIL (2x GALs)
2x 8 pin SIL (Latch)
1x 6 pin SIL (2x DS1813 reset)

Good grief lol

viewtopic.php?t=1576 and the links there should be useful for testing for maximum clock speed. Keep in mind that higher temperatures will pull the maximum speed down, as will lower voltages. I highly doubt that you'll damage anything by exceeding the maximum. 14MHz is a conservative rating for not just operation but meeting the guaranteed timing margins at that frequency. I expect a good design with fast parts will let the processor run a lot faster. My workbench computer, which I initially made when I didn't know nearly as much about high-frequency behavior in digital circuits as I do now, has 4MHz parts and starts having trouble just above 7MHz, so I run it at 5MHz for some margin. Faster memory should let it run even faster.

_________________
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?

Thanks Garth. It's more idle speculation at the moment regarding over clocking - I don't bother with it for my PC so I probably won't (initially, anyway) do so with my new design.
For the moment I'm working on understanding how to implement RS232 (using your guide and other sources) as I really want to get something other than an LCD working for I/O.
Also want to do VGA graphics, but that doesn't look altogether simple...