[Coco] RESET on CoCo 1/2 vs CoCo 3

[Arthur Flexser]

The shift-break reset technique will indeed break out of any program,
except those that have specifically guarded against it, on the CoCo 1 and
early CoCo 2s (ones that have the Color Basic version that supports 4K
ROMs). But, unlike ctrl-alt-reset on the CoCo 3, the technique breaks you
out into a weird memory mode--in effect, you fool the machine into
thinking you have 4K of RAM.  Pretty much anything you try to do in this
mode will give an ?OM error.  If you press reset again, without holding
down shift and break, you'll be right back in the program you broke out of
originally.  With certain special, cassette based software (CLOADM and
EXEC are among the few commands that work in 4K mode), you can capture an
image of the state of all 64K of RAM as it was when shift-break-reset was
pressed, which has been used as a powerful technique for removing copy
protection.  But, other than that, it is not of much practical use.

Art

On Sun, 25 Jan 2004, John Riddle wrote:

> I vaguely remember someone mentioning that there was a way to "force" the
> Coco 1 and earlier models of the Coco 2 to reset via a key combination and
> pressing the reset button (much in the same way that Ctrl-Alt-Reset will
> reset the Coco 3 back to basic).  I think it might have been
> shift-break-reset.  Does anyone remember anything like this?  Marty Goodman,
> you out there?
> 
> John
> 
> -----Original Message-----
> From: coco-bounces at maltedmedia.com
> [mailto:coco-bounces at maltedmedia.com]On Behalf Of Arthur Flexser
> Sent: Saturday, January 24, 2004 2:55 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] RESET on CoCo 1/2 vs CoCo 3
> 
> 
> A lot of software uses this the technique of resetting back to itself as a
> copy-protection tool, to make it harder for someone to break out and
> resave an unprotected copy.  This protection is done by replacing Basic's
> reset vector at $72 with something that points to the program's entry
> point.  The only thing you can do is to find the place in the program that
> does this and knock out that instruction, or the one which stores $55 to
> $71, also required for this technique to work.
> 
> Art
> 
> On Sat, 24 Jan 2004, Perry M Dueck wrote:
> 
> > Hi all,
> >
> > Although I owned a CoCo 3 system in 1987 to 1994 (and again from 2001 to
> > present and probably forever henceforth), I only recently have come into
> > ownership of a few CoCo 1 and CoCo 2 computers.
> >
> > Being primarily a CoCo 3 user, it was natural to hold down ALT  CTRL  and
> > press RESET to break out of programs and "reset" the entire machine to its
> > original power up state, and start fresh without powering the computer off
> > and then on again.
> >
> > With a CoCo 1 and 2, and certain software, when I want to break out of a
> > program, I'll press the RESET button on the back of the machine, but then
> > it sometimes will throw the computer back into the program I was using
> > (again, some software will do this, other software will not). This leaves
> > me with the only option of powering down the system, waiting for a bit (as
> > is customary with powering electronics off and then back on), and then
> > switching the computer back on to start off "fresh".
> >
> > Is this sequence of events on the CoCo 1 and 2 my only option for
> resetting
> > the machine in certain situations, or is there some key combination I can
> > use together with the RESET button (similar to the CoCo 3's  ALT  CTRL
> > RESET) to reboot the computer completely? Or perhaps some POKE commands I
> > can enter before loading and executing software with would otherwise not
> > allow me to break out of the program by simply pressing the RESET button
> on
> > the back of the computer?
> >
> > Thanks for your advice/comments.
> >
> > best regards, Perry
> >
> >
> >
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> > Coco at maltedmedia.com
> > http://five.pairlist.net/mailman/listinfo/coco
> >
> 
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