I heard that it wasn't too expensive to get crystals made so I thought about getting them made for the 65C02 and WDC 65C816S and for other processors. What is the fastest speed recommended for both? What speeds do you recommend for a beginner and what speed do you recommend for someone who knows what they are doing?

www.quartslab.com/
http://www.icmfg.com/

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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?

One thing that strikes me - is shorting the outputs wise? Definitely do the inputs, but with CMOS logic the outputs should be driven hard enough to be a non-issue, and I'd rather not deal with the possibility of accidentally activating the device's clamp diodes.

Of course, the best option would be to, where possible, use the "Picogate" devices, which would mean none were left wasted

_________________
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?

_________________
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?

For beginners, start at 1 or 2 MHz - you can get away with long connections and lots of stray capacitance and not worry about access times and propagation delays and still have everything work when you run this slow.

More experienced constructors can run up to the maximum rated clock speed for the processor (14MHz with current WDC devices.) At this speed, propagation delays and memory access times become significant and you have to spend time adding them up and ensuring you don't exceed the CPU timings - this can get involved.

Really advanced constructors will exceed the maximum rated processor speed - but if you do this you have to be prepared for things to fail. A sign that you are exceeding the maximum safe clock speed is unexplained, random misbehaviour of your system.

Readily available crystals and oscillators cover the most commonly used clock speeds - it is certainally not worth the cost of having a crystal custom-made unless you need to run at some obscure frequency for timing reasons.

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Shift to the left,
Shift to the right,
Mask in, Mask Out,
BYTE! BYTE! BYTE!

Has anyone here in the forums used an Atmel IC for high speed, high resolution clock generation? (i.e. many multiple frequencies from a single clock source?) Dividers are obviously lacking resolution anywhere near the input clock speed... I remember reading about it in these forums awhile back how someone used an AVR for an excellent programmable clock source.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

_________________
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?

AVR's when used as a timed clock, you may see error. Circuit Cellar had a featureless clock project. Ed Nisley's project showed that with a Arduino packaged 16-mhz resonator, he got a error of 33 seconds over 138 minutes. Based on the national time clock signal.

May be okay for the task though.

Dimitri

Not intentionally hijacking this thread but... I've already figured out my clocks for EEPROM copy/ SRAM run modes, 1 fast & one slow, no variable frequency needed. I'm just trying to make my digital pulse width analyzer more useful than just analyzing automotive injectors, typically 500uS to 4mS on an 8 cyl engine. Not too much speed or even variation in desired clocks needed to clock 16 bit counters. These CPLDs are capable of 80+ MHz with what I've programmed them for....

Despite this, I have always been intrigued by digitally controlled clock generation, but PLLs were always above my understanding. I used to look at a CD4046 datasheet, I still remember the part # without looking it up!, and think how do I really make this thing work?!

ChuckT, there's a simple circuit I made here with a VCO good to many MHz above the 6502 capability, using a 74S124. It does get hot though, which means it is using quite abit of current (I think about 100mA). It does the job done for benching/prototyping with abit of jitter although it has not interfered with software execution @~10MHz.

9th post from the bottom.
viewtopic.php?t=1503&start=60

-EyE

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65Org16:https://github.com/ElEctric-EyE/verilog-6502