Re: ROMs replacement

From: Gerrit Heitsch <>
Date: Tue, 18 Sep 2012 18:27:35 +0200
Message-ID: <>
On 09/18/2012 05:22 PM, Spiro Trikaliotis wrote:
> Helo Segher,
> * On Tue, Sep 18, 2012 at 12:44:48AM +0200 Segher Boessenkool wrote:
>>> Thus, the data bus is not really tristate.
>> A MOS input does not sink any significant current.
> A good point that I totally overlooked. Yes, with MOS, this setup should
> be (almost?) equivalent to tristate. But academically, it still isn't. ;)

Problem is, you can't really tristate an input. No matter what, you will 
always have the input stage visible as a load. Holds true with TTL too.

But the real question is, what signals of the 6510 are controlled by 
AEC? The 'A' stands for 'address', but does it also control other 
signals including the data bus? From the 'scope readings I'd say it also 
controls R/_W, but can't really say anything about the data lines.


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Received on 2012-09-18 17:00:35

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