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1 ********************************************************************
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2 * Boot - OS-9 Level Two ROM Boot module
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3 *
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4 * $Id$
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5 *
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6 * Ed. Comments Who YY/MM/DD
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7 * ------------------------------------------------------------------
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8 * 1 Created BGP 98/??/??
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9
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10 nam Boot
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11 ttl OS-9 Level Two ROM Boot module
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12
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13 ifp1
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14 use defsfile
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15 endc
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16
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17 tylg set Systm+Objct
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18 atrv set ReEnt+rev
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19 rev set $01
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20 edition set 1
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21
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22 mod eom,name,tylg,atrv,start,size
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23
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24 size equ .
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25
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26 name fcs /Boot/
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27 fcb edition
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28
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29 start equ *
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30 * obtain bootfile size at known offset
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31 pshs u,y,x,a,b,cc
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32 orcc #IntMasks mask interrupts
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33
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34 * allocate memory from system
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35 * memory will start at $8000, blocks 1, 2, 3 and 3F
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36 * we allocate $100 bytes more so that the memory will start
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37 * exactly at $8000
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38 ldd #$8000-$1300
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39 os9 F$BtMem
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40 bcs Uhoh
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41
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42 stu 3,s save pointer in X on stack
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43 std 1,s save size in D on stack
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44
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45 * TRICK! Map block 4 into $4000, copy our special ROM copy code
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46 * there, then jmp to it!
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47 lda $FFA2
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48 pshs a
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49 lda #$04
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50 sta $FFA2
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51 ldd #RelCodeL code less than 256 bytes
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52 leax RelCode,pcr
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53 ldy #$4800
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54 Copy lda ,x+
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55 sta ,y+
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56 decb
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57 bne Copy
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58
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59 Jump jsr $4800 * jump to rel code
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60 puls a restore original block at $4000
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61 sta $FFA2
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62
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63 * Upon exit, we return to the kernel with:
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64 * X = address of bootfile
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65 * D = size of bootfile
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66 * CC = carry cleared
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67 ExitOK andcc #^Carry clear carry
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68 Uhoh puls u,y,x,a,b,cc,pc
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69
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70
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71 * this code executes at $4800
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72 RelCode equ *
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73 lda #$4E CC3 mode, MMU, 32K ROM
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74 sta $FF90
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75 sta $FFDE ROM/RAM mode
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76
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77 * Map ROM Blocks in
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78 ldd #$3C3D
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79 std $FFA4
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80 lda #$3E
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81 sta $FFA6
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82
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83 * Map block 1 at $6000
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84 lda $FFA3
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85 pshs a
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86 lda #$01
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87 sta $FFA3
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88 * Copy first 8K of ROM
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89 ldx #$8000
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90 ldy #$6000
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91 Loop1 ldd ,x++
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92 std ,y++
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93 cmpx #$A000
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94 blt Loop1
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95
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96 * Map block 2 at $6000
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97 lda #$02
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98 sta $FFA3
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99 * Copy second 8K of ROM
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100 ldx #$A000
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101 ldy #$6000
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102 Loop2 ldd ,x++
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103 std ,y++
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104 cmpx #$C000
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105 blt Loop2
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106
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107 * Map block 3 at $6000
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108 lda #$03
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109 sta $FFA3
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110 * Copy third 8K of ROM
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111 ldx #$C000
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112 ldy #$6000
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113 Loop3 ldd ,x++
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114 std ,y++
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115 cmpx #$E000
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116 blt Loop3
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117
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118 * Copy remaining ROM area ($8000-$1400)
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119 lda #$3F
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120 sta $FFA3
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121 ldx #$E000
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122 ldy #$6000
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123 Loop4 clr $FFDE put in ROM/RAM mode to get byte
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124 ldd ,x++
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125 clr $FFDF put back in RAM mode to store byte
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126 std ,y++
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127 cmpx #$EC00
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128 blt Loop4
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129 * ldx #$6000
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130 * ldy #$E000
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131 *Loop5 ldd ,x++
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132 * std ,y++
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133 * cmpx #$6C00
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134 * blt Loop5
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135
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136 lda D.HINIT restore GIME HINIT value
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137 sta $FF90
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138 puls a restore org block at $6000
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139 sta $FFA3
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140 lda #$03
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141 sta $FFA6
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142 ldd #$0102
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143 std $FFA4
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144 rts
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145
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146 RelCodeL equ *-RelCode
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147
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148 * Fillers to get to $1D0
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149 fcc /99999999999999999999999999999999999999999999999999/
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150 * fcc /99999999999999999999999999999999999999999999999999/
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151 * fcc /99999999999999999999999999999999999999999999999999/
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152 fcc /99999999999999999999999999999999999999999999999999/
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153 fcc /99999999999999999999999999999999999999999999999999/
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154 fcc /99999999999999999999999999999999999999999999999999/
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155 fcc /999999999999999999999999999999999999999999999999999/
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156
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157 emod
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158 eom equ *
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159 end
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