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From: eric@amiga.UUCP (Eric Cotton)
Newsgroups: net.micro.cbm
Subject: Re: Quitting a game on C64
Message-ID: <807@amiga.amiga.UUCP>
Date: Wed, 5-Mar-86 14:41:29 EST
Article-I.D.: amiga.807
Posted: Wed Mar  5 14:41:29 1986
Date-Received: Fri, 7-Mar-86 07:46:47 EST
References: <148@daisy.UUCP> <940@rlgvax.UUCP>
Distribution: net
Organization: Commodore-Amiga Inc, Los Gatos, CA
Lines: 59
Summary: reseting a c64

/************************** munch, munch, munch *****************************/

In article <940@rlgvax.UUCP>, bub@rlgvax.UUCP ( Mongo Mauler) writes:
> > Hi.
> > 
> > My cousing has recently bought a Commodore 64 system with disk.
> > He loads a game from a disk and starts running it.
> > Now, when he wants to stop the games and/or load another one or
> > do something in basic, he has to turn the machine on and off.
> > IS there a keyboard key sequence that he can use to return him
> > to on board basic from a running program???
> > Any pointers are greately appreciated!!
> > Thank you.
> > -- 
> > --
> > 		NAME:	Michael Umansky (misha)
> > 		E-MAIL: ucbvax!hplabs!nsc!daisy!misha
> > 		WORK:
> > 			Daisy Systems Corp.
> > 			700B Middlefield Road
> > 			Mountain View, CA  94039-7006
> > 			(415) 960-7166 (work)
> > 		HOME:
> > 			94 Cassia Ct.
> > 			Hayward, CA  94544
> > 			(415) 886-4805 (home)
> 
> You can try pressing the RUN/STOP key, then while holding it down
> smartly tap the RESTORE key.  If this doesn't reset the machine, and
> the game has no facility to exit to BASIC, turning the machine off is
> your only recourse.  The power switch is the C64 'reset/reboot' switch!

When I developed games here at Commodore for the C64 one trick we used to
reset the machine was to ground the reset line on the user port.  We installed
two wires onto the user port (either by soldering directly on it or,
preferably, soldering onto the corresponding positions on a slip-on edge
connector), the first wire to reset (line 3) and the second to ground
(line 1).  [Refer to page 397 (appendix i) in the C64 programmer's ref. Guide.
for pin-outs.] The other ends of the two wires should be connected to a
switch (the type that completes the circuit only when depressed, breaks the
circuit when let go.

This method completely resets the computer, as if turned of and then on again.
There is a difference, however.  Nearly all program instructions are still
intact.  While developing games written in assembly, if the game would hang,
we could reset with this switch and then either try running (SYSing) it again,
or examine memory locations or program segments - great for debugging.  As
for BASIC, when the C64 is reset in this fashion many BASIC memory locations
are trashed (by power-up initialization).  So while most of the BASIC program
might be intact, ponters and the first bit of the program would be changed.

Hope this helps.  If you have problems with this or I didn't explain well
please let me know.

	Eric Cotton
	Sr. Software Eng.
	Commodore

"My hovercraft is full of eels." - M. Python