[Coco] [Color Computer] Another flaky question: RAM "snapshot" device

[Art Flexser]

I believe there was such a gadget for the CoCo, a Rompack called Magic Key.  
I'm not certain it used the NMI, but it seems likely.  It was advertised in
Rainbow for a short while.  Anybody know anything about it?  Anybody have the
ad?  Did Rainbow review it?

As a commercial product, I'm pretty sure it was unsuccessful, probably because
it was overpriced.  I never heard of anyone who actually claimed to have one.

On the CoCo 1 and 2, there was a snapshot technique that involved holding down
the shift and break keys while pressing Reset.  That broke you out of any
program by fooling the initialization routine for memory setup into thinking you
had a 4K machine, causing the memory map of RAM to get reconfigured.  Most
commands wouldn't work in this mode ('out of memory' error), but CLOADM and EXEC
would, which enabled restoration of the 64K memory mode and snapshotting of
memory by running a short ML program.  This was not workable on a CoCo 3 (and
probably not on late CoCo 2s, either) because the test for 4K was eliminated
from the memory setup ROM routine in late versions of Color Basic.

Art

On Wed, 18 Feb 2009, Steven Hirsch wrote:

> On Wed, 18 Feb 2009, David Bush wrote:
> 
> > I would like to be able to disassemble and modify these
> > programs so they can run off my hard drive. To that end,
> > I have in mind a hardware device which would work as
> > follows: I load and run the software. While it is
> > running, I push a button, and the CPU receives a
> > non-maskable interrupt. The address of the NMI routine
> > is also changed, so control is transferred to another
> > program while the copy-protected program is still
> > sitting in RAM. I could then transfer RAM to a disk file
> > to examine and disassemble at my leisure.
> 
> I'm surprised that such a thing doesn't already exist.  There were many 
> NMI based "cracker" devices for the Apple 2, and that platform could 
> support some very bizarre protection schemes!
> 
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