Re: Commodore 64 Ultimate Cartridge project

From: Marko Mäkelä <>
Date: Tue, 8 May 2012 20:54:37 +0300
Message-ID: <20120508175437.GA2441@x220>
On Tue, May 08, 2012 at 05:51:03PM +0200, Michał Pleban wrote:
>For now, I think it would be best to use 512k SRAM and a CPLD. It could 
>be configured to handle the SD-card interface, or even reprogrammed to 
>emulate the REU or whatever. I think this way it will be much more 

Right, implement a REU-like device that would additionally speak with 
the SD-card. Use a small EEPROM for bootstrapping. The C64 would tell 
the REU-like device to do transfers between SD and on-cart RAM, or 
between on-cart RAM and main RAM.

Last time I looked (several years ago), Atmel had some combination of 
AVR and programmable logic. I wonder if that could be useful for 
implementing the SD interface.

Also, I have been suggested that some microcontroller+logic SoCs can be 
configured to look like a ROM chip from the outside. That could enable 
an almost single-chip solution.

The same idea could be used on the Vic-20 and plus/4. At boot, bring in 
an 8k or smaller bootstrap ROM. Load a menu or whatever to RAM, and 
finally load the image, set up the desired configuration in both 
internal memory, on-cart memory, and on-cart I/O circuits (for emulating 
different bank switching cartridges and so on).

I have been thinking about this. My Vic Flash Plugin with its 4MB 5-volt 
flash is a dead end. In theory, it hosts all the Vic-20 software ever 
written. In practice, it takes too long to reload the flash image when 
you want to change something. It would be handier to plug in an SD card.  
Even if the cartridge did not understand a full-blown file system, it 
would be fast to set up the images on the SD card on a beefier machine.

Best regards,


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Received on 2012-05-08 18:00:38

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