Re: ROM Dump of Amiga Keyboard controller

From: Gerrit Heitsch <>
Date: Tue, 10 Jun 2014 20:33:39 +0200
Message-ID: <>
On 06/10/2014 08:12 PM, Martin Hoffmann-Vetter wrote:
>> Remember that the external clock is divided by 2 internally and that
>> the datasheet claims that minimum clock is 200 kHz.
> Ohh, you are right. That's a third problem. How to detect the right state of
> the phi2 signal generated from the clock signal.

You might not have to besides making sure that you feed bytes to Port PC 
at half the clock speed (remember padding bytes for write accesses and 
dummy accesses done by the 6502) since it only counts what it finds on 
the port when PHI2 goes low internally. It shouldn't matter whether the 
Byte it reads has been there for the full cycle or only half of it.


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Received on 2014-06-10 19:02:37

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