[Coco] What would a CoCo successor have to have as a minimum?

Little John sales at gimechip.com
Tue Nov 23 02:32:48 EST 2010

Just wanted to toss in a bit about extending the CPU...
William Mensch extended the 6502 to 16 bits with his 65816. It could still 
run as a 6502, but also had it's 16-bit mode with a 16-Megabyte address 
space. There was also a version called the 65802 which was a 65816 that 
could be plugged directly in place of a 6502 (I don't think it supported the 
extra memory though). Might something similar not be possible with the 6809?

----- Original Message ----- 
From: "Mark McDougall" <msmcdoug at iinet.net.au>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Monday, November 22, 2010 8:26 PM
Subject: Re: [Coco] What would a CoCo successor have to have as a minimum?

> On 23/11/2010 11:31 AM, Theodore (Alex) Evans wrote:
>> If one wants to get pedantic, 8ns giving you 125MHz is only 4x faster 
>> than
>> 25MHz, not 5x faster.
> Damn, my stupid calculator is broken, it _insists_ that 125/25=5, not 4! 
> :(
>> especially since there is nothing stopping you from giving the video side 
>> 32
>> bit access even with no changes to the CPU.
> ...except for the minor fact that you don't have 32-bit memory...
>> If we are modifying the 6x09 CPU, I would like to see support for 24 or 
>> 32
>> bit addresses in the CPU and a true 16-bit ALU, and yes a wider data bus
>> would be nice too. To support all this there would have to be another CPU
>> mode because at the very least it would mess up the stack.
> Surely that's just a matter of changing the port widths on John Kent's 
> CPU09 core... right John? Maybe you should've used generics when you wrote 
> it!?!
> Sorry to be sarcastic Alex, I couldn't help myself. But you do have a 
> tendency to over-simplify everything.
> Regards,
> -- 
> |              Mark McDougall                | "Electrical Engineers do it
> |  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"
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