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57
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1 \ 6809 assembler
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2
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3 BASE @ HEX
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4
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5 : DEFER CREATE 0 , DOES> @ EXECUTE ;
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6 : IS ' >BODY ! ;
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7
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8 VOCABULARY ASSEMBLER
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9 ASSEMBLER ALSO DEFINITIONS
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10
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11 ' C! DEFER VC! IS VC! \ Vectorize the important words so we can cross
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12 ' C@ DEFER VC@ IS VC@ \ assemble and self-assemble using the same code.
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13 ' ! DEFER V! IS V!
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14 ' @ DEFER V@ IS V@
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15 ' C, DEFER C, IS C,
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16 ' , DEFER , IS ,
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17 ' HERE DEFER HERE IS HERE
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18 ' ALLOT DEFER ALLOT IS ALLOT
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19
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20 VARIABLE VDP
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21 : VHERE ( --- addr)
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22 VDP @ ;
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23 : VALLOT VDP +! ;
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24 : VC, ( c --- )
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25 VHERE VC! 1 VALLOT ;
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26 : V, ( n ---)
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27 VHERE V! 2 VALLOT ;
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28 : ORG VDP ! ;
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29
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30 : <MARK ( --- addr )
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31 HERE ;
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32 : <RESOLVE ( addr ---)
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33 HERE 1+ - C, ;
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34 : >MARK ( --- addr )
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35 HERE 0 C, ;
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36 : >RESOLVE ( addr --- )
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37 HERE OVER 1+ - SWAP VC! ;
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38
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39 VARIABLE ?PREBYTE VARIABLE PREBYTE \ Byte $10 or $11 before opcode
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40 VARIABLE ?OPCODE VARIABLE OPCODE \ Opcode byte
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41 VARIABLE ?POSTBYTE VARIABLE POSTBYTE \ Byte after opcode indicating mode.
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42 VARIABLE ?OPERAND \ Address or data after instruction.
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43 VARIABLE MODE \ True is direct addressing false is other.
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44 VARIABLE DPAGE \ Direct page address.
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45 : SETDP ( n ---) \ Set direct page.
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46 100 * DPAGE ! ;
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47 0 SETDP
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48
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49 : NOINSTR \ Reset all the instruction flags so there will be no instruction.
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50 ?PREBYTE OFF ?OPCODE OFF ?POSTBYTE OFF ?OPERAND OFF MODE OFF ;
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51 : A; \ Assemble current instruction and reset instruction flags.
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52 MODE @ IF \ direct addresiing?
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53 DUP DPAGE @ - 0FF U> IF \ Is address 16 bits?
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54 2 ?OPERAND ! \ Indicate 16 bits address.
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55 OPCODE @ 0F0 AND 0= \ Change opcode byte.
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56 IF 70 OPCODE +!
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57 ELSE 20 OPCODE +!
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58 THEN
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59 ELSE 1 ?OPERAND ! \ Indicate 8 bis address.
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60 THEN
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61 THEN
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62 ?PREBYTE @ IF PREBYTE @ C, THEN
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63 ?OPCODE @ IF OPCODE @ C, THEN
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64 ?POSTBYTE @ IF POSTBYTE @ C, THEN
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65 ?OPERAND @ IF
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66 CASE ?OPERAND @
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67 1 OF C, ENDOF \ 8 bits data/address.
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68 2 OF , ENDOF \ 16 bits data/address.
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69 3 OF HERE 1+ - C, ENDOF \ 8 bits relative address.
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70 4 OF HERE 2 + - , ENDOF \ 16 bits realtive address.
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71 ENDCASE
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72 THEN NOINSTR ;
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73
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74
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75 : LABEL A; HERE CONSTANT ;
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76
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77
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78 HEX
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79 : flag10 \ Indicate that next instruction has prebyte $10
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80 ?PREBYTE ON 10 PREBYTE ! ;
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81 : flag11 \ Indicate that next instruction has prebyte $11
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82 ?PREBYTE ON 11 PREBYTE ! ;
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83
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84 : # \ Signal immediate mode.
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85 MODE OFF -10 OPCODE +! ;
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86
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87 : USE-POSTBYTE \ Signal that postbyte must be used.
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88 MODE OFF
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89 ?POSTBYTE ON
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90 OPCODE @ 0F0 AND 0= IF
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91 60 OPCODE +!
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92 ELSE
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93 OPCODE @ 80 AND IF
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94 10 OPCODE +!
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95 THEN
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96 THEN ;
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97
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98 : [] \ Signal indirect mode.
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99 MODE @ IF \ Indirect addressing with 16-bits addres, no postbyte made yet.
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100 USE-POSTBYTE
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101 9F POSTBYTE ! \ Make postbyte.
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102 2 ?OPERAND ! \ Indicate 16-bits address.
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103 ELSE
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104 POSTBYTE @ 80 AND 0= IF \ 5-bits address format already assembled?
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105 POSTBYTE @ 1F AND DUP 10 AND 0<> 0E0 AND OR
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106 1 ?OPERAND ! \ Signal operand.
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107 POSTBYTE @ 60 AND 98 OR POSTBYTE ! \ Change postbyte.
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108 ELSE
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109 POSTBYTE @ 10 OR POSTBYTE ! \ Indicate indirect addressing.
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110 THEN
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111 THEN ;
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112
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113 : ,R \ Modes with a constant offset from a register.
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114 CREATE C,
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115 DOES> USE-POSTBYTE
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116 C@ POSTBYTE ! \ Make register field in postbyte.
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117 DUP 0= IF
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118 84 POSTBYTE +! DROP \ Zero offset.
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119 ?OPERAND OFF
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120 ELSE
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121 DUP -10 >= OVER 0F <= AND IF \ 5-bit offset.
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122 1F AND POSTBYTE +!
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123 ?OPERAND OFF
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124 ELSE
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125 DUP 80 + 100 U< IF \ 8-bit offset.
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126 88 POSTBYTE +!
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127 1 ?OPERAND !
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128 ELSE
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129 89 POSTBYTE +! \ 16-bit offset.
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130 2 ?OPERAND !
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131 THEN
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132 THEN
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133 THEN ;
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134 00 ,R ,X
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135 20 ,R ,Y
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136 40 ,R ,U
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137 60 ,R ,S
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138
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139 : AMODE \ addressing modes with no operands.
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140 CREATE C,
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141 DOES> USE-POSTBYTE
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142 C@ POSTBYTE !
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143 ?OPERAND OFF ;
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144 080 AMODE ,X+ 081 AMODE ,X++ 082 AMODE ,-X 083 AMODE ,--X
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145 085 AMODE B,X 086 AMODE A,X 08B AMODE D,X
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146 0A0 AMODE ,Y+ 0A1 AMODE ,Y++ 0A2 AMODE ,-Y 0A3 AMODE ,--Y
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147 0A5 AMODE B,Y 0A6 AMODE A,Y 0AB AMODE D,Y
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148 0C0 AMODE ,U+ 0C1 AMODE ,U++ 0C2 AMODE ,-U 0C3 AMODE ,--U
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149 0C5 AMODE B,U 0C6 AMODE A,U 0CB AMODE D,U
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150 0E0 AMODE ,S+ 0E1 AMODE ,S++ 0E2 AMODE ,-S 0E3 AMODE ,--S
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151 0E5 AMODE B,S 0E6 AMODE A,S 0EB AMODE D,S
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152
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153 : ,PCR \ Signal program counter relative.
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154 USE-POSTBYTE
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155 DUP
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156 HERE ?PREBYTE @ - 3 + - \ Subtract address after instruction
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157 80 + 100 U< IF \ 8-bits offset good?
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158 3 ?OPERAND !
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159 8C POSTBYTE !
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160 ELSE
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161 4 ?OPERAND !
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162 8D POSTBYTE !
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163 THEN ;
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164
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165 : USE-OPCODE ( c ---)
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166 ?OPCODE ON
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167 OPCODE ! ;
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168
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169 : IN1 \ Simple instructions with one byte opcode
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170 CREATE C,
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171 DOES> >R A; R> C@ USE-OPCODE ;
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172 12 IN1 NOP 13 IN1 SYNC
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173 19 IN1 DAA 1D IN1 SEX
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174 39 IN1 RTS 3A IN1 ABX
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175 3B IN1 RTI 3D IN1 MUL
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176 3F IN1 SWI : SWI2 SWI flag10 ; : SWI3 SWI flag11 ;
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177 40 IN1 NEGA 50 IN1 NEGB
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178 43 IN1 COMA 53 IN1 COMB
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179 44 IN1 LSRA 54 IN1 LSRB
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180 46 IN1 RORA 56 IN1 RORB
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181 47 IN1 ASRA 57 IN1 ASRB
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182 48 IN1 ASLA 58 IN1 ASLB
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183 48 IN1 LSLA 58 IN1 LSLB
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184 49 IN1 ROLA 59 IN1 ROLB
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185 4A IN1 DECA 5A IN1 DECB
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186 4C IN1 INCA 5C IN1 INCB
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187 4D IN1 TSTA 5D IN1 TSTB
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188 4F IN1 CLRA 5F IN1 CLRB
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189 \ Though not no-operand instructions the LEA instructions
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190 \ are treated correctly as the postbyte is added by the mode words.
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191 30 IN1 LEAX 31 IN1 LEAY
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192 32 IN1 LEAS 33 IN1 LEAU
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193 : DEX LEAX -1 ,X ; : INX LEAX 1 ,X ;
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194 : DES LEAS -1 ,S ; : INS LEAS 1 ,S ;
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195 : DEY LEAY -1 ,Y ; : INY LEAY 1 ,Y ;
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196
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197 : BR-8 \ relative branches with 8-bit offset
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198 CREATE C,
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199 DOES> >R A; R> C@ USE-OPCODE 3 ?OPERAND ! ;
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200 20 BR-8 BRA 21 BR-8 BRN
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201 22 BR-8 BHI 23 BR-8 BLS
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202 24 BR-8 BCC 25 BR-8 BCS
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203 24 BR-8 BHS 25 BR-8 BLO
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204 26 BR-8 BNE 27 BR-8 BEQ
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205 28 BR-8 BVC 29 BR-8 BVS
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206 2A BR-8 BPL 2B BR-8 BMI
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207 2C BR-8 BGE 2D BR-8 BLT
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208 2E BR-8 BGT 2F BR-8 BLE
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209 8D BR-8 BSR
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210
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211 : LBRA
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212 A; 16 USE-OPCODE 4 ?OPERAND ! ;
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213 : LBSR
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214 A; 17 USE-OPCODE 4 ?OPERAND ! ;
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215
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216 : BR16 \ Relative branches with 16-bit offset.
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217 CREATE C,
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218 DOES> >R A; R> C@ USE-OPCODE flag10 4 ?OPERAND ! ;
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219 21 BR16 LBRN
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220 22 BR16 LBHI 23 BR16 LBLS
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221 24 BR16 LBCC 25 BR16 LBCS
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222 24 BR16 LBHS 25 BR16 LBLO
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223 26 BR16 LBNE 27 BR16 LBEQ
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224 28 BR16 LBVC 29 BR16 LBVS
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225 2A BR16 LBPL 2B BR16 LBMI
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226 2C BR16 LBGE 2D BR16 LBLT
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227 2E BR16 LBGT 2F BR16 LBLE
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228
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229 : IN2 \ Instructions with one immediate data byte.
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230 CREATE C,
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231 DOES> >R A; R> C@ USE-OPCODE 1 ?OPERAND ! ;
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232 1A IN2 ORCC 1C IN2 ANDCC 3C IN2 CWAI
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233 : CLC ANDCC 0FE ; : SEC ORCC 01 ;
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234 : CLF ANDCC 0BF ; : SEF ORCC 40 ;
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235 : CLI ANDCC 0EF ; : SEI ORCC 10 ;
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236 : CLIF ANDCC 0AF ; : SEIF ORCC 50 ;
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237 : CLV ANDCC 0FD ; : SEV ORCC 02 ;
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238 : % ( --- n) \ Interpret next word as a binary number.
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239 BASE @ 2 BASE ! BL WORD NUMBER? drop DROP SWAP BASE ! ;
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240
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241 : REG \ Registers as used in PUSH PULL TFR and EXG instructions.
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242 CREATE C, C,
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243 DOES> ?OPERAND @ IF \ Is a PUSH/PULL instruction meant?
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244 1+ C@ OR
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245 ELSE
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246 C@ POSTBYTE +! \ It's a TFR,EXG instruction.
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247 THEN ;
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248 06 00 REG D, 06 00 REG D
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249 10 10 REG X, 10 01 REG X
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250 20 20 REG Y, 20 02 REG Y
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251 40 30 REG U, 40 03 REG U
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252 40 40 REG S, 40 04 REG S
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253 80 50 REG PC, 80 05 REG PC
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254 02 80 REG A, 02 08 REG A
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255 04 90 REG B, 04 09 REG B
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256 01 A0 REG CC, 01 0A REG CC
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257 08 B0 REG DP, 08 0B REG DP
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258
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259 : EXG A; 1E USE-OPCODE ?POSTBYTE ON 0 POSTBYTE ! ;
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260 : TFR A; 1F USE-OPCODE ?POSTBYTE ON 0 POSTBYTE ! ;
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261 : STK \ Stack instructions.
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262 CREATE C,
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263 DOES> >R A; R> C@ USE-OPCODE
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264 1 ?OPERAND ! 0 ;
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265 34 STK PSHS 35 STK PULS
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266 36 STK PSHU 37 STK PULU
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267
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268 : OP-8 \ Instructions with 8-bits data.
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269 CREATE C,
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270 DOES> >R A; R> C@ USE-OPCODE
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271 MODE ON
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272 1 ?OPERAND ! ;
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273 00 OP-8 NEG 03 OP-8 COM
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274 04 OP-8 LSR 06 OP-8 ROR
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275 07 OP-8 ASR 08 OP-8 ASL
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276 08 OP-8 LSL 09 OP-8 ROL
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277 0A OP-8 DEC 0C OP-8 INC
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278 0D OP-8 TST 0E OP-8 JMP
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279 0F OP-8 CLR
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280 90 OP-8 SUBA 0D0 OP-8 SUBB
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281 91 OP-8 CMPA 0D1 OP-8 CMPB
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282 92 OP-8 SBCA 0D2 OP-8 SBCB
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283 94 OP-8 ANDA 0D4 OP-8 ANDB
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284 95 OP-8 BITA 0D5 OP-8 BITB
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285 96 OP-8 LDA 0D6 OP-8 LDB
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286 97 OP-8 STA 0D7 OP-8 STB
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287 98 OP-8 EORA 0D8 OP-8 EORB
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288 99 OP-8 ADCA 0D9 OP-8 ADCB
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289 9A OP-8 ORA 0DA OP-8 ORB
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290 9B OP-8 ADDA 0DB OP-8 ADDB
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291 9D OP-8 JSR
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292
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293 : OP16 \ Instructions with 16-bits daia.
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294 CREATE C,
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295 DOES> >R A; R> C@ USE-OPCODE
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296 MODE ON
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297 2 ?OPERAND ! ;
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298 93 OP16 SUBD 0D3 OP16 ADDD
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299 9C OP16 CMPX 0DC OP16 LDD 0DD OP16 STD
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300 9E OP16 LDX 0DE OP16 LDU
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301 9F OP16 STX 0DF OP16 STU
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302 : CMPD SUBD flag10 ; : CMPY CMPX flag10 ;
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303 : LDY LDX flag10 ; : STY STX flag10 ;
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304 : LDS LDU flag10 ; : STS STU flag10 ;
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305 : CMPU SUBD flag11 ; : CMPS CMPX flag11 ;
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306
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307 \ Structured assembler constructs.
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308 : IF >R A; R> C, >MARK ;
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309 : THEN A; >RESOLVE ;
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310 : ELSE A; 20 C, >MARK SWAP >RESOLVE ;
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311 : BEGIN A; <MARK ;
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312 : UNTIL >R A; R> C, <RESOLVE ;
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313 : WHILE >R A; R> C, >MARK ;
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314 : REPEAT A; 20 C, SWAP <RESOLVE >RESOLVE ;
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315 : AGAIN 20 UNTIL ;
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316 22 CONSTANT U<= 23 CONSTANT U>
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317 24 CONSTANT U< 25 CONSTANT U>=
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318 26 CONSTANT 0= 27 CONSTANT 0<>
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319 28 CONSTANT VS 29 CONSTANT VC
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320 2A CONSTANT 0< 2B CONSTANT 0>=
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321 2C CONSTANT < 2D CONSTANT >=
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322 2E CONSTANT <= 2F CONSTANT >
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323
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324 : ENDASM \ End assembly.
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325 A; PREVIOUS ;
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326 FORTH DEFINITIONS
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327 : ASSEMBLE \ Start assembly.
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328 ALSO ASSEMBLER NOINSTR ;
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329
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330 : CODE CREATE -3 ALLOT ASSEMBLE ;
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331 : END-CODE [ ASSEMBLER ] ENDASM [ FORTH ] ;
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332
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333 PREVIOUS FORTH DEFINITIONS
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334
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335 BASE ! \ Restore the original base.
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