[Coco] The Definitive Post on the CC-Five ;)

[jdaggett at gate.net]

On 28 Jan 2007 at 22:38, Joel Ewy wrote:

> I realize it's far off, but since you mentioned the idea of improving
> the CPU, I wonder about the possibility of integrating the MMU/DAT
> with the 6x09 in such a way that concatenated index registers could be
> used as pointers into a much larger, linear address space.  So perhaps
> Z is a new virtual 32-bit address register composed of X and Y.  This
> won't affect the stack on interrupts, etc.  But it would allow you to
> directly manipulate data structures larger than 64K, as the 32-bit
> address can be fed directly into the MMU/DAT, and blocks mapped
> temporarily in for the duration of the instruction.  Obviously there
> would still be code size limitations.  But if we have big graphcs, big
> audio, etc, it would be nice to have big pointers.
> 
> JCE
> 

Joel

Any expansion of the CPU would be to drop the DAT and expand the Program co 
unter to 24 bits. That would yield a direct addressing capability of 16M. That 
would put it on par with the TC70 and MM1. Alternatively a "CALL" and 
"RETURN" instruction would need to be added to the assembler. I believe that 
would not be to difficult to implement. The assembler would have to determine if 
the address jump were out of the range of the current 64K block and addjust the 
upper byte of the PCR to reflect which block of 64K the call would be. In the CPU 
the PCR could be stacked internally with the CALL instruction and pulled back off 
with the RETURN instruction. 

james

Just some musings I  had. 
> jdaggett at gate.net wrote:
> > Mark
> >
> > Just a thought on expanding the vector table should there be an
> > improvement to the CPU. There are 16 bytes there that are not used
> > and an expanded vector table would be nice. 
> >
> > Also could put a RTC in at FF80 to FF8F, another block 16 bytes that
> > are not used. 
> >
> > james
> >
> > On 29 Jan 2007 at 11:40, Mark McDougall wrote:
> >
> >   
> >> jdaggett at gate.net wrote:
> >>
> >>     
> >>> Also some things I wanted to do is to increase the vector table
> >>> from $FFF1 down to $FFE0. At $FFF0/$FFF1 would be the 6309 trap
> >>> vector, and then use $FFE0 to $FFEF as vectors for PS2 Keyboard,
> >>> PS2 Mouse, and any other 6 vectors deemed necessary. 
> >>>       
> >> So the PS/2 keyboard won't map to the Coco keyboard? Is that so you
> >> can use all the keys on a PC keyboard?
> >>
> >> Regards,
> >> Mark
> >>
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> >
> >
> >
> >   
> 
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