Re: Eagle CAD design and fabrication of C64 & Plus4 cartridges

From: Jim Brain <>
Date: Fri, 9 Dec 2016 12:15:33 -0600
Message-ID: <>
On 12/9/2016 6:22 AM, smf wrote:
> On 09/12/2016 07:16, Jim Brain wrote:
>> Designing a soft-banking solution requires at least 2 ICs (a latch to 
>> hold the bank and something to combine IO1, R/W, and Phi2), should be 
>> 3 (the C128 really needs the dual FF clock fixer circuit that Skoe 
>> and Martin Hoffmann-Vetter designed), and that started to sound like 
>> work...
> Could you do bank switching with a single registered pal/gal? 
Yes, but that requires a programmer, etc., and that increases the 
complexity quite a bit.
> I can't find anything about the dual FF clock fixer.
It's on the EasyFlash  Essentially, it delays the clock start by 1/2 
dotclock period and shortens it.  From Martin's response to me:

DotCLK  _| |_| |_| |_| |_| |_| |_| |_| |_
Phi2 =OE_______|               |_________
Phi2'   _________|       |_______________
Phi2"=WE_____________|       |___________

Possibly Martin will respond on list with more detail.  Since he 
responded to me personally, I'd prefer he post to the list.
> Would your design also allow you to make a c128 native cartridge?
> The difference seems to be 16k instead of 8k for ROML/ROMH and no 
> game/exrom jumper.
It would require a jumper wire from A13 on the ROMs to A13 on the cart 
connector, and if Mark wants, I can quickly add that :-)

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Received on 2016-12-09 19:00:02

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