[Coco] Need to Port NitrOS-9 6x09 L2 to N8VEM's New 6x0x Board

Frank Swygert farna at amc-mag.com
Wed Nov 27 09:40:24 EST 2013


Date: Tue, 26 Nov 2013 08:30:33 -0700
From: Darren A<mechacoco at gmail.com>

On Tue, Nov 26, 2013 at 7:55 AM, Frank Swygert wrote:
If the board supports the 6809E it will support the 6309E. The difference
is in software, not hardware (as far as the CPU itself is concerned),
remember? We stick 6309E's in CoCos that were designed for the 6809E all
the time...

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Their technical paper states that they are NOT using the 6809E but rather
the non "E" version.  I would assume that a 6309P is likewise pin-for-pin
compatible with a 6809P but can't say for sure.

The non "E" 6309  may be more difficult to source, but they do exist as
evidenced by this eBay listing:

<http://www.ebayitem.com/151087599927>

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Good thing I put the "E" on the end of mine! The "E" is for external clock, in case anyone didn't know that. The use of an internal clock 6809 means that the board would not be able to be overclocked though. The good side is it means the peripheral chips aren't tied to the same clock as the CPU, but then that is just particular to the CoCo design -- the CPU and peripheral chips could have used different clocks, but Tandy tied everything to the same clock chip to save money (as the Motorola "sample" design did -- Tandy basically followed that...).
  

-- 
Frank Swygert
Editor - American Motors Cars Magazine
www.amc-mag.com




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