[Coco] CoCo Progression...

[David Gacke]

The new CPU would be backward compatible with the old CPU. Also, it's
much easier to implement some of the new features in the list of items
you mentioned if they are attached to a new cpu.

A possible idea would be to leave the addresses from 0-ffff as is for
legacy support, including the bank switching, gime register maps, etc.
And build the new features in above that address.

Also, it's easy to emulate a CPU, it's much harder to emulate the
idiosyncrasies (timing, etc) of a graphics chip. 


Dave

-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com]
On Behalf Of Mark McDougall
Sent: Monday, September 27, 2004 4:58 AM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] CoCo Progression...

James Dessart wrote:

>> Second, it's much easier to breathe new life into a possible CoCo 4
>> design by moving to a newer CPU, like an ARM. This gives you readily
>> available development tools like GCC and linux, not to mention many
>> other open source projects. But those aren't even necessary.
> 
> I have to agree that in-system emulation is probably better than just 
> reimplementing the CPU. Both Palm and Apple have used this technique
to 
> move to a new architecture, and it seems to have worked well for both
of 
> them.

I'm confused!

You're talking about designing a whole new computer and calling it 'CoCo
4'? 
  A new CPU and new graphics capabilities? Purely from a CoCo
enthusiast's 
perspective - what's the point? You can't run CoCo software on it. Why
not 
call it the 'Apple 4'?

I was talking about building a new CoCo in an FPGA - enhanced
capabilities 
such as overclocking the 6x09 CPU, enhanced graphics, VGA output, maybe 
ethernet/USB etc - but always backwards compatible with the original
CoCo. 
So you could play Donut Dilemma and run OS/9 at 2MHz, but also switch in
a 
few MB of extended RAM, run a 1024x768 256-colour VGA display, surf the
web 
etc at 40MHz on a modified OS/9 if you so wished.

Or am I missing something here?

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do
it
| <http://members.optushome.com.au/msmcdoug> |   with less resistance!"

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