[Coco] Assembler modifications and a super 6309 processor

[Paul Fitch]

I've said several times that the way to get the Coco 4 was to beef up the
6309 and the GIME.  If you are adding instructions, don't just consider 8/16
bit variations.  Some 32bit instructions would be cool.  Of course, I would
think the compiler/assembler/linker tools should be 100% up to speed before
the "new" chip was released.  

> -----Original Message-----
> From: coco-bounces at maltedmedia.com 
> [mailto:coco-bounces at maltedmedia.com] On Behalf Of Darren A
> Sent: Tuesday, September 08, 2009 3:43 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Assembler modifications and a super 6309 processor
> 
> On 9/8/09, jdaggett at gate.net  wrote:
> > Another Questionfor the Software Guru's out there:
> >
> > <snip>
> >
> > Adding the Immediate Mode for instructions like SBC, AND, 
> EOR, OR and 
> > ADC for the the E,  F, and W registers is rather easy. Would it be 
> > worth the effort to undertake this? I can put all those all on page 
> > three of the opcode map and they would have the same 
> opcodes as their 
> > page one instructions. The $11 page code would just switch target 
> > register acted on. Real simple to do.
> 
> ----
> 
> Looking at the opcode map, I think you would want to use the 
> $10 page code for instructions using W (and use the same base 
> opcode as the instructions for B).  The 6309 variants for D 
> already share the same base opcode as A.
> 
> If you add new instructions, could you also add a new bit to 
> the MD register to enable/disable those instructions?  Some 
> existing 6309 software may expect certain opcodes to trigger 
> an Illegal Instruction exception.
> 
> Darren
> 
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