SUBMITTED BY: SIR SKULL


------------------------------------------------------------------------
I                            Invalid OpCodes                           I
I                                                                      I
I                              Compiled By:                            I
I                                                                      I
I                                Sir Skull                             I
I                                --- -----                             I
I                                                                      I
I                        (for the 6502/6510 chips)                     I
------------------------------------------------------------------------


     Well..  As  yu  all  know,  there  are  some  ML  instructions  not 
documented  for yur  C64 or 6502/6510 chips...  So here they are!!  Fuck 
the spelling ok? I've been    kind enough to compile them...

           Time, dudes.
                                        Sir Skull.

                                  ------------


     Generally,  each  bit  in  a 6502  opcode  represents  a  different 
instruction  type or addressing mode.  An opcode can be broken down with 
the  three most significant bits representing type,  and the other  bits 
giving the mode.  There are,  of course,  exceptions,  but we can  still 
postulate  what the 6502 thinks it sees when it encounters an  undefined 
number.

     Here  are the unofficial (Invalid) Opcodes in the following format: 
HEX #3(Mnemonic,  Addressing mode) Brief description,  other  addressing 
modes.

 04: (NTW,implied)       This byte and byte after ignored.

 1B: (NTH,implied)       This byte and two bytes after ignored.

 07:  (SLO,Zeropage)     This Command shifts memory left then ORA's the 
                         Acc. with this memory.
   OTHER MODES:
 0F: (Absolute)
 17: (Zpage,x)
 1F: (Absolute,x)

 27:  (RLA,Zpage)        Roll memory location left, then AND the Acc. 
                         with Result.
   OTHER MODES:
 23: (indirect,x)
 2F: (absolute)
 37: (Zpage,x)
 3B: (Absolute,y)
 3F: (Absolute,x)

 43: (SRL,indirect,x)    Shifts memory right, LDA with the result

 4B:  (SRA,immediate)    Shift Acc right, then AND Acc. with immediate 
                         data.

 47: (SRE,Zpage)         Shift memory Right then EOR Acc with memory.
   OTHER MODES:
 4F: (Absolute)
 57: (Zpage)
 5F: (Absolute,x)

 67: (RRA,Zpage)         Roll memory right, then ADC memory to the acc.
   OTHER MODES:
 6F: (Absolute)
 73: (indirect,y)
 77: (Zpage,x)
 7B: (Absolute,y)
 7F: (absolute,x)

 87: (AAX,Zpage)         AND the Acc. with the X register.
   OTHER MODES:
 8F: (Absolute)
 97: (Zpage,y)

 8B: (AAX,Immediate)     AND the Acc, X register, and Immediate data.

 A3: (LAX,Indirect,x)    LDA and LDX from the same location.
   OTHER MODES:
 A7: (Zpage)
 AB: (Immediate)
 AF: (Absolute)
 B3: (Indirectly)
 B7: (Zpage,x)
 BF: (Absolute,x)

 C3: (DCP,Indirect,x)    DEC memory, then CMP it with the Acc.
  OTHER MODES:
 C7: (Zpage)
 CF: (Absolute)
 D3: (Indirect,y)
 D7: (Zpage,x)
 DF: (Absolute,x)

 CB:  (XAS,immediate)    AND the X Reg. with 8, Then SBC immediate data 
                         from X.

 EB: (SOC,Immediate)     SBC one from the Acc, and then Data immediately 
                         following.

 E3: (ISC,indirect,x)    INC memory location, then SBC result from Acc.
   OTHER MODES:
 E7: (Zpage)
 EF: (Absolute)
 F3: (Indirect,y)
 F7: (Zpage,x)
 FB: (Absolute,y)
 FF: (Absolute,x)


     Note  that the results for all of the above commands are stored  in 
the  Accumulator(Ref 'Acc.' in the text) except as follows:  AAX results 
are  stored in memory location given by data after  AAX(Immediate  mode) 
results,  and  LAX  results  are placed in both the Acc.  and in  the  X 
Register.  DCP results are shown in memory and in the processor's status 
byte. XAS results are put in the X register only.

     Presently,  only a few Assemblers will accept these new  Mnemonics. 
If  yur  Assembler doesn't,  Modify it,  or,  store the command as  BYTE 
statements...

     I   have   not  doccumented  all  the   codes   here.   There   are 
others(Including Opcodes called 'DTH'.  ie:  DeaTH,  Acid Crash, etc...) 
This  is  just  to  point  out  that  there  are  other  ways  of  doing 
multifunction  commands...  And yes,  they are faster than doing it  the 
long way...

     Anyway, Till next time.... Happy Hacking!!!!

                             Sir Skull

 ------------------------------------------------------------------------------


  Oh ya, Phone:
                 Barataria BBS      613-234-4714