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From: Mark on 20 Jan 2010 19:55
In article
<f782ee02-3f2e-4e0d-af66-0e733d3bd8e7(a)j19g2000yqk.googlegroups.com>,
daniel.otoole(a)ucd.ie says...
>On Jan 19, 1:58�am, Mark <m...(a)marks-labREMOVE.com> wrote:
>> I recall the ISEpic cartidge had a 2K? RAM inside and a bit of glue logic.
>> You downloaded the freezer program into the ISEpic to prepare for a
>> snapshot as it didn't have any built-in ROM.
>
>Which explains why I (still) need to make 5.25s from .d64s for the two
>ISEPIC knock off carts I have... I never thought they'd use RAM
>instead of ROM when I got them. I suppose they can be updated more
>easily but it sure makes it a pain in the butt to upload every time...

It's possible to add a diode or two and 2.5-3V battery to the cartridge to
have it save the contents of the RAM for as long as the battery holds out.
The CMOS static RAM would only draw a few microamps when not being used. I'd
expect the battery to last for weeks at least. Found a schematic using NiCd
here: http://schematics.dapj.com/2006/10/battery-backup-for-sram-or.html
You'd have to cut the +5V power between the RAM and the rest of the circuit
to insert the battery backup. (Probably not worth it....)

Cheers,

-Mark

From: DanSolo on 21 Jan 2010 09:26
On Jan 21, 12:55 am, Mark <m...(a)marks-labREMOVE.com> wrote:
> It's possible to add a diode or two and 2.5-3V battery to the cartridge to
> have it save the contents of the RAM for as long as the battery holds out..  
> The CMOS static RAM would only draw a few microamps when not being used. I'd
> expect the battery to last for weeks at least. Found a schematic using NiCd
> here:http://schematics.dapj.com/2006/10/battery-backup-for-sram-or.html
> You'd have to cut the +5V power between the RAM and the rest of the circuit
> to insert the battery backup.   (Probably not worth it....)


Or maybe just make a ROM chip with the software and replace the
RAM? :-)
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