[Coco] TC-9

[Frank Pittel]

If you make the gime replacement available to the coco community in some
way I'll buy you an AT keyboard adaptor!!

Frank

PS - notice I didn't say anything about you making a few pennies in the process.


On Mon, Jul 07, 2008 at 07:39:51PM -0400, Chuck Youse wrote:
> On Mon, 2008-07-07 at 18:02 -0500, Mark Marlette wrote:
> > Chuck,
> > 
> > There are free CPU cores, etc. Some have dabbled here but there is no  
> > GIME FPGA, others will say it isn't that hard, etc. Proof is in the  
> > pudding. If it isn't that hard, then do it, no time, busy, etc...Not  
> > implying you here.....There is a lot going on in the GIME.
> > 
> 
> Well, one of the problems with implementing the GIME as a stand-alone
> FPGA stems from the fact that the GIME performs quite a few analog
> functions, and the digital functions on any suitable FPGA will be at the
> wrong voltage levels.  E.g., composite and RGB outputs, not to mention
> the clock generation - as I'm sure you know the 6809 likes to drive its
> internal circuitry off the E clock.  So any drop-in GIME replacement
> would have to be a board of sorts, an FPGA with some external
> components.  
> 
> If it's a matter of implementing a 6809 + GIME on a chip and interfacing
> that to an external bus, that's one thing.  If it's a drop-in board to
> replace the GIME, that's another.  But as I stated before, if you're
> going to go that far, might as well integrate a lot more into the FPGA.
> 
> If your comments were meant as a gentlemanly challenge, I'll take it!
> But I want a free AT keyboard interface for my CoCo when I finish ;)
> 
> > Some have booted to a green screen, etc but we all know that there is  
> > a lot of work in the details of a project and to get one that works,  
> > 95%+ of the apps requires a bunch of time. Details, details, details.
> > 
> 
> If I were to do this, I'd probably put a 6809 and a GIME-style
> MMU/interrupt controller on a chip, and interface that to a multi-slot
> Coco-style hardware bus through some LVX-family transceivers or
> something.  The core+RAM can run at one speed, and external bus accesses
> can be synchronized to a free-running E clock @ 2MHz, much like the
> early 68ks did for 6800 peripherals.
> 
> I wouldn't bother with the graphics functions of the GIME, as I don't
> care for RSDOS compatibility - might put in some logic to drive a VGA
> display and keyboard, but certainly not in a CoCo/SAM compatible
> fashion.
> 
> > Then the cost. Last I checked some of the FPGA prices were $250+. Sure  
> > there are bigger, better and faster ones now but my point is the same.  
> > This is a labor of love and small volume manufacturing costs more than  
> > one would think unless they have lived it.
> 
> A suitable FPGA with more than enough area for a 6809 and GIME (with
> room to spare) would be an XC3S250E - the 144TQFP/4ns speed grade runs ~
> $15 at qty 1. 
> 
> > I tip my hat to you and your FDC controller project!!!! Nice job.
> 
> Thanks!  Means much coming from Cloud-9. :)
> 
> C.
> 
> 
> 
> 
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