Re: Introduction

From: Boisy Pitre <>
Date: Wed, 29 May 2013 10:01:18 -0500
Message-Id: <>
Thanks for your comments.

The Liber809 for the Atari completely replaces the 6502 with the 6809. This was done for several reasons:

1) Simplicity of design. It was my first hardware project, so I wanted to minimize risk.
2) Physical size. The Liber809 was intended to be used in multiple Atari A8 systems, all of which have different board layouts and clearances. Making the Liber809 as physically small as possible was important to allow it to fit easily in the most systems.

I think there would need to be some support for I/O lines because of the NitrOS-9 operating system which I would intend to port to a 6809-equipped C64. NitrOS-9 wants as much RAM as possible. and so it would be necessary to switch in/out the ROMs.


On May 29, 2013, at 4:42 AM, Michał Pleban <> wrote:

> Hello!
> Boisy Pitre wrote:
>> My main interest is in adapting the 6809 to the C-64 like I've done with =
>> the Atari A8s ( <>)
>> I've done a bit of research on what may be needed to do this, =
>> specifically with regard to the 6510 and its built in PIA port. I'm =
>> wondering what the interest level for something like this would be.
> That sounds interesting. I cannot figure from your blog, whether you run
> 6502 and 6809 concurrently, or do you replace the 6502 CPU completely
> with 6809?
> With regard to the I/O lines of the 6510, as Ruud pointed out you don't
> need them as long as you're happy with default memory configuration and
> no tape support. But as I see you are running some advanced operating
> systems on the machine, you would probably like to utilize full RAM of
> the machine.
> You could possibly sacrifice the User Port to drive these pins.
> Otherwise you need to carve some address space for an IO controller
> which would drive them.
> Regards,
> Michau.
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Received on 2013-05-29 16:00:08

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