Basically, as soon as the computer finishes you (and it says 'Finish him)
 hit the start button for the other player (ie. if you are player 1, hit F2).
 This does not cost a credit and player 1 does not have to hit start so does
 not have to use a credit.  The winner of the fight (just screw around to
 get it over quickly) continues to fight the computer and has not
 lost a credit.
 
 Of couse your score and 'wins in a row' is reset - but its reset if you
 use a credit anyways
 
 The short of it:
 1) Load game
 2) Press F10 for setup, hold SHIFT while typing D, I, and then P (DIP).
 3) Turning SWITCH 5 to ON will give you FREE PLAY (unlimited continues)
 4) The change will take effect instantly, no need to save changes
    (unless you want to keep it in the config file) or reload.
    (However, see #4 below to find out about what kind of changes
    require reloading)
 
 Here are the intense details:
 1)
 I have tested this on MK v1.0 for the IBM PC (both with and without
 the cheat patch by Stimpson J. Cat) as well as "v1.1", the 1/4/94
 version updated by the MKFIX.EXE from Acclaim.  So it basically
 seems to work on any "release" version, but I did not test it on
 any of the beta releases.  However, since the cheat involves the
 "F10 Setup Screen" I highly doubt it works on the beta version
 which had a separate SETUP.EXE.  They were tested with a
 Soundblaster v1.0, 486/33, 8 megs RAM.  (This may seem irrelevant
 but one of the below Switches does affect sound card output)
 
 2) Load the game.  Go to the setup screen by hitting F10.  At the
    setup screen, hold SHIFT, and press the letters "D", "I", and then
    "P" in that order.  It doesn't matter if you hold left or right
    shift, as some people were discussing.  You don't hold D-I-P
    simultaneously or anything, just hold SHIFT the whole time then
    basically type "DIP".
 
 3) A screen will pop up with this list:
 
         SWITCH 0: ON
         SWITCH 1: ON
         SWITCH 2: ON
         SWITCH 3: OFF
         .(etc)
         .(etc)
         SWITCH 8: OFF
 
    The default is with those first 3 switches on, and the rest off.
 4) 
 Now about these switches.  For one thing, SOME of the switches are
 a real pain in the ass to test through playing the game because
 they do NOT take effect until you reload the game after "EXIT &
 SAVE" from the SETUP screen.  Basically, things like FREE PLAY do
 not require reloading the game since they do not require loading a
 set of graphics or sound, but things like turning
 fatalities/blood/sound on or off DO require reloading the game
 since they require loading a different set of graphics or sound.
 Here are a FEW things I have found out from testing the DIP
 switches so far.
 
 NOTE: All of these tests were done using Sub Zero, and knowing
 those bastards at Midway they might have different effects
 depending on who you use.  Also, aside from all switches ON or all
 OFF, I did not test like "Switches 1,4,7 ON, all the rest off" or
 anything like that.  Again, certain switches being ON/OFF in
 combination might very likely produce secret effects.  Finally,
 with each individual switch, just because I said it only affects
 one thing (I.E. SWITCH 0=Fatality), doesn't mean it might not
 affect something else.  I only mentioned the first major thing I
 noticed in certain cases.
 
 ALL SWITCHES SET TO OFF:
      No blood, no fatalities, the text of MIDWAY PRESENTS is yellow
      rather than white, etc mentioned individually below
 
 ALL SWITCHES SET TO ON:
      Blood, fatalities, FREE PLAY (YES!), comic book ad shown, etc.
      mentioned individually below
 
      (Each of the below was tested with SWITCH x: ON, all the rest
       OFF, except as noted.)
 
 SWITCH 0: (does not affect blood during match) (default ON)
      ON=Fatalities ON
      OFF=Fatalities OFF
 
 SWITCH 1: (does not affect fatalities) (default ON)
      ON=Blood ON (during match)
      OFF=Blood OFF
 
 SWITCH 2: (default ON)
      ON=Sound ON during title sequence (does not affect sound in game)
      OFF=Sound OFF during title sequence
 
 SWITCH 3: (default OFF)
      ON=Music ON, Sound Effects OFF (speech off,etc. I have a
                                      strong feeling this is equal
                                      to "force Adlib mode")
      OFF=Music ON, Sound Effects ON
 
 SWITCH 4: (default OFF)
      ON=CPU does Fatality EVERYTIME he/she beats you (Switch 0 must
         be on)
      OFF=Normal/Random
 
 SWITCH 5: (default OFF)
      ON=Free Play ON
      OFF=Free Play OFF (Credits=4)
 
 SWITCH 6: (default OFF)
      UNKNOWN
 
 SWITCH 7: (default OFF)
      UNKNOWN
 
 SWITCH 8: (default OFF)
      CPU recovers slowly from an attack
 
 Hex editing will let you play unlimited/continuous games:
 
 Hex edit MK.EXE
 Search for A7 0C 03 FF FA 04
 Change to: A7 0C 03 FF FA 0A
 


 Cheat Mode
 Press [F10] to enter the setup menu. Hold [Shift] and type DIP to display a set of
 dip switches that can alter game play. Turn on one of the following dip switches to
 activate the corresponding cheat function. Note: the game may need to be
 restarted in order for some codes to be completely enabled. 

 Switch Effect 
 1 Toggle fatalities 
 2 Toggle blood 
 3 Toggle comic book offer 
 4 Toggle CPU fatalities 
 5 Toggle unlimited continues 
 6 Slow CPU recovery 


 Unlimited credits
 During a loss against the CPU, press [F2] when the phrase "Finish Him!" appears.
 A two player match will begin. Choose any fighter and select Sub-Zero as player
 two. Win the fight and allow player two's counter drop to zero. The previously lost
 CPU match will restart without the use of any credits.


 Fight against Reptile
 Kill your opponent with a double flawless match and a fatality on The Pit, after
 various objects pass over the moon.


 Blinking eyes
 Once you get to Goro and Shang Tsung, you should be on the skull level. If you
 go all the way to the left you will see some eyes blinking. They are three fighters
 in that black shadow. The first is Reptile, the second is Ermac, and the third is
 Smoke.