Re: [stella] Re: 2600's TIA & the TV Boy

[Kevin Horton <khorton@xxxxxxxxxxx>]

At 07:53 PM 8/19/01 -0700, you wrote:


> > There's only one way it's gonna be done and that's through an FPGA.  It 
> > would be impossible to make a true custom chip since the required 
> > quantities are pretty low.
>
> At least one guy on this list is thinking relatively large 
> quantities...  I can also see Activision wanting something like this 
> although technically it's hardware piracy due to the "priveleged" 
> technical documentation used.  The Toymax thing, from what I've been told, 
> is not an optimal chipset for 2600 compatibility.  I'm under NDA so I 
> can't give any details.  You'd be surprised what they did to kludge that thing.

Hmmm.  Dunno.  Would it still be piracy even though the end result was of a 
totally different design than the original?  i.e. HDL vs. NMOS transistor 
layout?  Or does it count because the design is based off the original work?


> > I think an FPGA is a pretty good "fit" for this, and would work well.
>
> What about the power demands?

Shouldn't be a problem.  The FPGAs don't seem to soak much juice since they 
are running at a low clock rate, and they are CMOS.


> >   Unfortunately, my FPGA dev package is good only for up to 10K gate 
> > chips so I won't be able to integrate anything but the TIA, RIOT, and 
> > bankswitching stuff.  I can't afford the $5000 to upgrade it :-P. (I'm 
> > using Xilinx Foundation, less than 8K gates version.)
>
> What about the 6507?  Isn't there a way to reduce that down to something 
> low power?  There are a lot of low power miniaturized 65c02s cores out 
> there but none of them that I know of have authentic cycle counts.  They 
> are all optimized for faster operation.

I wanted a go at FPGA'ing the 6502 at some point but I'm still a little 
hazy about how it works internally.  I wrote an emulator for the 6502 in 
PIC assembly in an attempt to understand it better.  This was fairly 
informative, and I almost have enough to make an attempt at recreating it.

WDC does indeed sell a VHDL version of the 65C02 core, but you can bet 
they'd want tons to use it, and one would have to sign an NDA.


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