6809/6809E compatibility

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robcfg
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6809/6809E compatibility

Post by robcfg »

Hello, wonderful people!

I'd like to ask about the difference between 6809/6309 and 6809E/6309E processors.

It looks like the standard and E versions have a set of pins with different functions, and the direction of the E and Q pins seem to be reversed.

I upgraded my D200 with a 6309EP, and on the other hand my D64 is running smoothly with a 6309P, and I'm not sure if it can be a problem or not.

And, if it isn't could you put a standard 6809 on a Dragon?

Cheers,
Rob
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snarkhunter
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Re: 6809/6809E compatibility

Post by snarkhunter »

Hello,

According to Wikipedia, the "E" version of both processors "needs an external clock generator" (which was an internal feature of the standard version).

https://en.wikipedia.org/wiki/Motorola_6809#6809

Is this what you were looking for?
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robcfg
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Re: 6809/6809E compatibility

Post by robcfg »

I know that, but my question is more if standard and E versions are interchangeable, and if they are not how come that I have a D64 with a standard 6309 working well.
sorchard
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Re: 6809/6809E compatibility

Post by sorchard »

Hi Rob!

In general the internal/external clock versions are not interchangeable so I am amazed it works at all. As you say, there are a number of pin differences but the ones that matter in the Dragon are the E and Q directions.

So in your D64 you have both SAM and CPU trying to drive the E and Q clocks i.e. not a healthy situation. My guess is that the SAM is driving much more strongly than the CPU. There's even a chance the drivers fried in the CPU shortly after power up, allowing SAM to drive the clocks. Either way, this is not something I would try myself.
Stew
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robcfg
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Re: 6809/6809E compatibility

Post by robcfg »

Hi Stew,

Thanks for the info!

It would have been nice to have it mentioned on the datasheets...

I'll look to get a proper 6309E in order to avoid damaging anything else.

The surprising bit is that it works as if it were a completely compatible replacement.
6309Dragons.jpg
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sixxie
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Re: 6809/6809E compatibility

Post by sixxie »

Unless you’ve just unwittingly discovered more extreme cleverness from Hitachi… ;)
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robcfg
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Re: 6809/6809E compatibility

Post by robcfg »

I consider it an option!

That it maybe detects an incoming clock signal and disables the internal one.

I've seen weird edge cases with several processors, but having it running without problems for more than 4 years... that would be too much to ask :mrgreen:
bluearcus
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Re: 6809/6809E compatibility

Post by bluearcus »

Where did you source the CPU? Those Chinese sellers are not shy of relabeling...
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