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Could an AVR be used as a cart rom?


cbmeeks

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  • 2 weeks later...

I use an AVR in my Bee3 cart design for the Intellivision :-

 

http://atariage.com/forums/topic/225566-bee3-its-alive/

 

However, the Intellivision has a multiplexed address/data bus and takes several clock cycles in each bus phase. The latest design does have extra stuff around the AVR to make the CPUs life a bit easier.

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As a first thought, it might be possible to do something with an XMEGA at 32MHz and make use of the Z80's T-states. However, without investigating the problem in much more detail its just a theory. The first "gotcha" to overcome would be detecting the DRAM refresh cycles.

 

Edit: You'd also need 5v to 3v level conversion as well (if you go down the XMEGA route). That adds additional cost and PCB routing which might be a factor.

Edited by GroovyBee
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Can't afford an F18A. :-)

 

But it's along those lines. The propeller (http://forums.parallax.com/showthread.php/138254-TEXAS-INSTRUMENTS-TMS9918-9928-VDP-Emulation-on-Propeller?highlight=tms9928) can output video using software. Plus, it can emulate the SN76489 sound chip (among others) at the same time.

 

It's an experiment, really. What I want to do is emulate a ColecoVision using a *real* Z80 connected to the propeller. The propeller (prop) would then stand in as RAM/ROM for the Z80 and emulate the audio/video of the CV. Like a hybrid.

 

That's the dream, anyway.

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Yep. Hence, the propeller. :-)

 

My first idea was to simply create my own "multi-cart" but using the AVR to act as the ROM ( the original point of this post). But the more I get into it, the more I want my own hybrid CV.

 

I can't ever do anything simple. lol

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