[Coco] 6X09 -> HC11/HC12

[jdaggett at gate.net]

Mark

The HC705 is nothing like the HC11. More scaled down. Almost a modern 6800. 
The 6808 is the big brother of the 6805 series a very similar archetecture. The 
HC11 like the 6809 has the two accuamlators that can be concated into one 16 bit 
register. The HC11 only has three pointer registers, X, Y and S. The HC11 has 16 
bit as well as 8 bit instructions. The HC12 is a true 16 bit processor. It has identical 
programming model. Other than having more instructins and 16 bit architecture, you 
can think of an HC12 as and HC11 on steriods. CPU12 copre runs at 4 times teh 
rate of the CPU11 core. In some of its flavors it will allow 8 bit databuss 
configuration. The CPU core, CPU12 is an upward migration from the HC11and 
different from than CPU16 used in the HC16. Of the three, HC05, HC11 and HC12 
the HC12 source code is more compatible to the 6809. From looking at some of the 
OS9 source code in a HC11/HC12 IDE,  my guess is that better than 95% 
compatiblity in the source code.

Bear in mind the HC12 was designed after the HC16. The HC16 was an attempt to 
move users of the HC11 series ot a more powerful line. A blend of the the HC11 
and 68K CPUs. The problem was that the HC11 source and the HC16 source were 
not 100% compatible. So no one migrated to the HC16. Then came the 
HC12/HSC12. This processor and it s resultant CPU12 core is 100% source code 
compatible. HC11 users cantake their HC11 source code and reassemble it on 
HC12 assemblers and run. No touchup,  no mess not fuss. The HC12 adds more 
instructions and support for fuzzy logic. The HC12 does have commands that do 
allow going through lookup table much easier. 

james
    

On 16 Jan 2004 at 5:08, Mark Marlette wrote:

Date sent:      	Fri, 16 Jan 2004 05:08:07 -0600
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From:           	Mark Marlette <mmarlett at isd.net>
Subject:        	Re: [Coco] 6X09 -> HC11/HC12
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> At 08:38 PM 1/15/2004 -0800, you wrote:
> 
> Jim,
> 
>  From what I recall. The HC11 is an 8bit MCU and the HC12 is a 16bit
>  MCU. I 
> have never programmed the either. I have looked at code for a HC705
> which is similar to the HC11. I would agree with the post that that
> HC12 looks like the 68000 though. Seems logical from Motorola's
> standpoint to do that.
> 
> Regards,
> 
> Mark
> Cloud-9
> 
> >I have a question for you CPU guru's out there.  Which is most like
> >the 6X08, the HC11 or the HC12? Jim
> >
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