[Coco] 16/32 bit 6809 derivative

Richard Cavell richardcavell at mail.com
Mon Sep 25 18:28:03 EDT 2017


   I just want to add my thoughts:

   6800->6809 was a transition that Motorola expressly supported.  They
   mention it several times in the official Programming Manual.  68K was a
   different architecture.  Although it might be possible to transcode
   6809 code to 68k, I'm not sure what the point would be.

   Sent: Monday, September 25, 2017 at 11:03 PM
   From: "James Ross" <jrosslist at outlook.com>
   To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
   Subject: Re: [Coco] 16/32 bit 6809 derivative
   Francis Swygert wrote:
   > ... It's not like the 6809 was that popular ...
   That's a good point. And you may very well be (and probably are) right.
   At the timeframe we are talking about, the Z80 may have been the most
   popular CPU (due to price) ... but that is just a guess.
   > My understanding was that there was some backwards compatibility on
   the
   > source code level, with just a few tweaks required to 6809 source to
   > compile on a 68K processor
   Hmm... perhaps you're thinking 6800 -> 6809. From what I have seen, 68k
   assembly language source is sufficiently different from 6809 that it
   would require a complete translation (transcoding) of source.
   James
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References

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