Re: ROM Dump of Amiga Keyboard controller

From: Rainer Buchty <>
Date: Wed, 11 Jun 2014 17:29:35 +0200 (CEST)
Message-ID: <alpine.DEB.2.02.1406111713410.14285@localhost>
On Wed, 11 Jun 2014, Gerrit Heitsch wrote:

> External test equipment can use this feature to test internal CPU 
> logic and I/O. A program can be loaded into RAM allowing the contents 
> of the instruction ROM to be dumped to any port for external 
> verification.

To me that -- optimistically -- confirms the "ROM-only" theory, although 
admittedly the wording is very vague.

The ROM-only approach makes things the easiest -- only ROM reads appear 
outside, program calling in RAM does not require external 
synchronization with regard to dropping reset to 5V, and you would have 
even full control over the I/O ports so that e.g. you could run a RAM 
test and I/O test first before tapping in the ROM read-out routine.

> But that might mean that you can only _write_ to any register, but any 
> read (RAM, ROM, I/O) will only happen from port PC. Unfortunatly, the 
> data sheet doesn't supply any more details but the term 'all memory 
> fetches' suggests this being the case. Otherwise I would expect it to 
> read 'all ROM fetches'.

I'm already suprised to see the "apply 10V to reset" hint there. 
Usually, such information is not publicly disclosed.

> To really know what's going on one would need a die shot.

Or be brave :) Not sure, how much /1 supply there's left, though.

As time allows, I'll try my luck with the 6500/11 I have ... In that 
very case I might even be able to see the external memory strobe come to 
life (which the /1 doesn't have).


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Received on 2014-06-11 16:00:04

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