[Coco] Multi-Processor 6809 Computer System

[John W. Linville]

On Tue, Apr 30, 2013 at 11:44:44AM -0400, Bill Gunshannon wrote:
> 
> > A muti-processor setup, if it could be made for the CoCo, wouldn't offer
> > any benefits unless code is written specifically to utilize this extra
> > processor... so I would have thought.
> 
> In a well designed SMP system different tasks would run on different
> processors so there would certainly be a gain in performance.

This is only true if you have multiple processes to run in the first
place, and if the tasks being run don't serialize due to any inherent
dependencies.

> >
> > That's why I suggested the idea of a faster 6809 made from an FPGA that
> > maintained the timing required by the GIME chip for video syncronization.
> 
> The faster processors paradigm does not necessarily scale as well as
> SMP and it can have bad effects on programs that rely on the speed of
> the CPU for timing.

This would seem to be contrary to Amdahl's Law:

	http://en.wikipedia.org/wiki/Amdahl%27s_law

	http://www.youtube.com/watch?v=WdRiZEwBhsM

> >
> > This would benafit ALL existing software... if it could be done.
> 
> As would SMP.  All changes are done at the OS level applications need
> not even know they are running on a multi-processor machine.

Not all software runs under OS-9.

> > Something along the lines of Sock Master's 4Mhz mod but reliable if
> > created with an FPGA to replace the stock 6809.
> >
> > Anyone with FPGA experience confirm this possibility?
> >
> > If possible, anyone in a position to try this? It could be the single
> > greatest expansion option for the CoCo3.
> 
> I think the single greatest expansion option would be a plug in Video
> Cartridge with better graphics and the ability to connect to modern
> technology displays.

Which would require new software to run any "better graphics" stuff --
software that will have more work to do in order to push that graphics
data around the screen.

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.