[Coco] Re: 68B09P - Datasheet?

[jdaggett at gate.net]

Kevin

The HC11 is an extention of the MC6801/03 CPU core. The 
HC11/12 was never based on the 6809. The HC11 initially was 
designated an 8 bit 64K memory map embedded processor. The 
HC12 is upward source compatible to the HC12. 

The HC12 does incorporate addressing modes from the 6809 like 
Inderect Indexed. Instructions like LEAx act the same but have 
different opcodes. 

This is the best way to describe the Motorola 8 bit processor   
progression:

6800 --> 6802 --> 6809

6801 --> 6803 --> 6811 --> 68HC11 --> 68HC12

6805 --> 68HC05  --> 68HC08


james

On 26 May 2005 at 14:11, Kevin Diggs wrote:

Date sent:      	Thu, 26 May 2005 14:11:37 -0700
From:           	Kevin Diggs <kevdig at hypersurf.com>
To:             	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
Subject:        	Re: [Coco] Re: 68B09P - Datasheet?
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> 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?
> 
>      kevin
> 
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