http://www.kickstarter.com/projects/208 ... s-personal

The Graphics speak for themselves.

Is the 6502 ready for a GPU?

I found it is using the Embedded Video Engine from FTDI Chip.

http://www.youtube.com/watch?v=xOJ0br7l ... r_embedded

FTDI has preliminary datasheets and stuff on there. All communication is SPI based which would require at least an SPI interface of sorts, maybe a small CPLD. Not a deal-breaker but it'd bloat your BOM somewhat..

The output of that chip could probably be modified to run VGA.

I’ve interfaced the original Gameduino with my 6502 prototype using 65SPI. By providing an external clock of 16MHz, the Gameduino can be fed with its maximum of 8MHz. In the near future I’m going to test performance.

The Gameduino 2 may seem overkill, but with enso’s 45MHz 65C02, it would be a nice match. Only hurdle is to provide SPI on CHOCHI

The Gameduino 2 has 256k of video memory, so for providing enough data and quick enough, a 65C816 would be more suitable.

However, I find the original Gameduino a better option for our 6502!

_________________
Marco

Marco,

Can you tell us how the original Gameduino worked for you, please? How were you using it? Text only?

Thank you... Regards, Mike

Hello Mike,

Initially I had tried the Gameduino on an ATMega328, which worked without issues. Of course due to the Arduino IDE, I could simply use the readymade libraries. Looking at those libraries I could determine how to access the Gameduino with bare bit banging the ports. It wouldn’t be a bad idea to convert some of the libraries in 6502 assembler routines. But u haven’t come to that.

The next step was to breadboard MARC-1 with 65SPI and the Gameduino. There I went into trouble. I had to add sufficient bypass caps and some extra ground wires. I also made the blunder to feed the XC9572XL (3,3V) with 5V. However, it did work, kind of, but not reliable.

65SPI is a 65xx compatible SPI interface created by Daryl Rictor [8BIT] in the forum.

MARC-1 is a MOS6502 based SBC with 48kB RAM and 16kB ROM running at 1,8432 MHz.


Finally I had MARC-1 on a PCB and made a better board for the XC9572XL with proper 3,3V VCC and sufficient bypass caps. On the picture you see how it was setup. I added one more detail to gain more speed. I fed the 3,6864 MHz (where PHI2 is derived from) to the EXTC in of 65SPI. Of course this doubled the speed of the Gameduino. EXTC can except up to 45 MHz, however the Gameduino excepts a maximum of 8 MHz. But that’s more than fast enough, even for games.


In my opinion, in combination with 65SPI, the Gameduino is a very capable video option. It doesn’t use any RAM of you system, it does text, graphics, sprites and soft scrolling in all directions. It operates at 3,3V to 5V and does sound too. You can omit the Gameduino startup screen. At startup, there is already a charset present in the Gameduino’s RAM, so you have immediate text mode to your disposal.

Do you intend to buy one?

_________________
Marco

Very nice - thanks for back-linking to the MARC-1 post, I'd surely read it at the time but it was worth a revisit.

Thank you, Marco.

I'm not sure I'll buy one. I'm just looking for GPU solutions that use an SPI interface for my SBC project.

BTW, your MARC-1 and 2 projects look fantastic. Bravo!

Cheerful regards, Mike