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

Subject: Re: [stella] Re: 2600's TIA & the TV Boy
From: Kevin Horton <khorton@xxxxxxxxxxx>
Date: Mon, 20 Aug 2001 00:46:11 -0500
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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