Re: Commodore 64 Ultimate Cartridge project

From: Michał Pleban <>
Date: Wed, 09 May 2012 10:30:02 +0200
Message-ID: <>

Anders Carlsson wrote:

> Somehow it sounds like you're describing a C64 version of the VIC-20
> Final Expansion?

Yes, it is definitely going in this direction.

But as I reviewed all the "final", "universal" and "ultimate" cartridges 
already available, I noticed that they are based on similar approaches:

* Stash as much FLASH as possible to store cartridge images.
* Provide the method of flashing the images from PC, and a menu to 
choose an image from the computer.
* Attach some useful circuitry such as SD-card interface for added value.

This is a nice approach, but severely limited to just emulating 
cartridge images plus whatever extra circuitry is glued in. What I want 
to do now is another step further:

* Instead of Flash, use a reprogrammable FPGA chip.
* Provide a solution to connect a SD-card.
* The boot ROM will load selected FPGA image from SD-card and put it 
into the FPGA.

This way the cartridge will not be limited to emulating just other ROM 
cartridges. The FPGA can do anything we program it to. If we just want 
to emulate a cartridge, then FPGA has memory so it will just serve as a 
ROM chip. But it can be programmed to act as REU as well. Or an Ethernet 
interface, or USB host, a Z80 card even. It can be anything.

As I checked part prices, the cost of building the card with one FPGA, 
one CPLD, 5V to 3.3V interface, SD-card connector, 512k SRAM plus some 
glue should be about $50 apiece. Not very bad.

I envision then a website where you can buy one item (the board), and 
then download all kinds of FPGA images and simply put them on the 
SD-card to reuse. Maximum user-friendly - no flashing the FLASH memory 
in the card, just a matter of copying one file.


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Received on 2012-05-09 10:00:09

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