[Coco] Re: 68B09P - Datasheet?

Frank Pittel fwp at deepthought.com
Thu May 26 20:31:39 EDT 2005

On Thu, May 26, 2005 at 02:11:37PM -0700, Kevin Diggs wrote:
> Hi,
> jdaggett at gate.net wrote:
> >The HC12 instruction set is more like that of the MC6809. There are 
> >more instrtuctions in the HC12 but it has one less register than the 
> >6809. That is the U  pointer register. 
> >
> >The HC12 is a good processor. The PICs offer better cost. 
> >
> >james
> >
> 	Didn't they have to whack the U because they wanted to use its 
> 	opcode encoding space to make PC relative addressing more flexible?

I'm not sure why the U stack was removed but I do know that it doesn't exist
on the 68hc11 either. I did spend a lot of years programming the 68hc11 and
never missed it.


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