Re: ROM Dump of Amiga Keyboard controller

From: Jim Brain <>
Date: Fri, 18 Jul 2014 19:23:51 -0500
Message-ID: <>
On 7/18/2014 2:18 PM, wrote:
>> And, I was able to dump out the entire 2kB of ROM. I also found out
>> that it looks like the system requires 4 cycles after RESET goes high to
>> start, and there needs to be some time while RESET is low to put things
>> in order.
> How do we define "high" and "low" here? Is "high" 5 or 10? Is "low" 5 or 0?
> In other words could you say bit more on the timing? Like at which cycles should what transitions happen?
I felt the transitions should happen on CLKext/2  (in other works, when 
the incoming clock falls for the 2nd time or 4th time, etc.

In the above, high means 5-10V (CPU running, either in regular or test 
mode), and low means 0v.  I found that if I put the system into RESET 
for internal clock periods (8 external cycles) and then put the system 
into test mode, the system came up correctly, but if I drove the system 
into TEST mode right after applying CLOCK and I did not run the CPU 
through a reset mode, it would not run my program correctly.

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Received on 2014-07-19 01:01:38

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