[Coco] CoCo 3 FPGA?

Thu Jul 26 12:32:23 EDT 2007

Joel

The FPGA clock may run at 50 MHz or even higher does not mean that the 
effective machine cycle time will be 50 MHz or more.  Even with FPGAs 
there are internal delays for routing and throu gh the logic itself. Depending 
on how many level sof gates it takes to do a function may slow the overall 
effective speed. 

John Kent's CPU 09, a MC6809 processor, actually runs at 12MHz due to 
the way the logic synthesizes even though the FPGA clock is 50 MHz. 
Depending on which FPGA  you use and how the logic is distributed I doubt 
much faster than about 35 MHz effective machine cycle for a 6809 core. 
Part that is limited to how fast the decode locig can do instruction and 
address mode from a given opcode. I h ave toyed around with various logic 
layout and the fastest time I  can get the address mode information from 
when the opcode is loaded into the instruction register at about 6.5nS. That 
would lead to about 60 MHz max with a Spartan 3 series processor. 

Maybe some of the Virtex FPGAs are faster. But they also carry a heftier 
price tag.

james

On 25 Jul 2007 at 23:15, Joel Ewy wrote:

> Leonard wrote:
> > Ok...I'll admit my ignorance, but I can over come it with questions?
> >  What's an FPGA and what will that mean for the hobbyist?  I think
> > an FPGA is a CoCo on a chip?  Does that mean its more of an
> > emulation then actual hardware?
> >   
> Leonard, this is sort of like emulation, but it is emulation
> implemented in programmable hardware, rather than emulation
> implemented in software running on a general purpose CPU.  So if the
> FPGA can be clocked at 50 MHz (to pull a number out of the air) the
> processor can run at 50 MHz. For all intents and purposes, this is
> real hardware.  But it is hardware that is programmable, and in some
> FPGAs, dynamically re-programmable while running.  So not only could
> it contain all the functionality of a CoCo 3, it could also be
> expanded to have Next-Generation CoCo features.  One could even leave
> a section of the logic free and implement all kinds of specialized
> algorithms in it, like encoding/decoding JPEG images in hardware,
> color quantization, floating point coprocessor, or whatever. > Would
> this mean a CoCo that can run SVGA?  > >   It very well could.  Just
> depends on what Gary has put in there. > Would this chip be for sale?
> > >   That all depends on Gary, of course!  :)  The chip itself is
> probably an off-the-shelf FPGA -- likely on an FPGA development board.
>  Those can be had for $100 - $???.  The development board would have
> everything you need to hook it up to a PC and program the logic array
> on the FPGA. Some even have goodies like VGA and keyboard ports built
> in.  One might need to cook up a little custom hardware to attach CoCo
> peripherals. The main issue is whether and on what terms Gary is
> willing to share his FPGA code.
> 
> It's unlikely that anybody's going to sell a packaged FPGA CoCo system
> as a consumer product, though I'd love it if somebody proved me wrong
> here.  But as a do-it-yourself project where somebody supplies the
> FPGA code, and maybe an interface board or two, and you buy your own
> FPGA development board -- that is eminently possible.  And we may be
> closer to it than ever before...
> 
> JCE
> > Leonard
> >
> >
> > -----Original Message-----
> > From: coco-bounces at maltedmedia.com
> > [mailto:coco-bounces at maltedmedia.com] On Behalf Of Shain Klammer
> > Sent: Wednesday, July 25, 2007 2:38 PM To: CoCoList for Color
> > Computer Enthusiasts Subject: Re: [Coco] A semi-real CoCo topic
> >
> > Hate, being a "me too" : )   but, I look forward to learning more
> > about this, especially what further plans you have (if any) - such
> > as adding other hardware and/or extensions...
> >
> > sk
> >
> > On 25/07/07, Rogelio Perea <os9dude at gmail.com> wrote:
> >   
> >> Now you're talking!
> >>
> >> Second here in line for the website visit :-)
> >>
> >>
> >> -=[ Rogelio ]=-
> >>
> >>
> >> On 7/25/07, Jim Cox <jimcox at miba51.com> wrote:
> >>     
> >>> Gary!
> >>>
> >>> Way cool.  I am looking forward to visiting you site.
> >>>
> >>> Jim
> >>>
> >>> On Wed, 25 Jul 2007 15:26:32 -0500
> >>>   "Becker, Gary" <Gary.Becker at amd.com> wrote:
> >>>       
> >>>> FYI
> >>>>
> >>>> I have almost finished the COCO3 in a FPGA. I have run
> >>>> several of the
> >>>> demo programs on Sock Master's web site. Of course, I am
> >>>> having issues
> >>>> with Boink. But I have successfully booted into
> >>>> NitrOS-9.
> >>>>
> >>>> I will be setting up a web site soon with pictures and
> >>>> details.
> >>>>
> >>>> Gary
> >>>>         
> >> --
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> >> Coco at maltedmedia.com
> >> http://five.pairlist.net/mailman/listinfo/coco
> >>
> >>     
> >
> > --
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> >
> >
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> >
> >   
> 
> 
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