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1187
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1 ********************************************************************
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2 * Boot - Disto RAMPak 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 * 5 Created ADK
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9 * 6 Fixed small bugs, improved speed BGP 98/10/20
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10
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11 nam Boot
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12 ttl Disto RAMPak Boot Module
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13
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14 * Disassembled 94/06/25 11:37:47 by Alan DeKok
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15
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16 ifp1
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17 use defsfile
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18 use rbfdefs
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19 endc
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20
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21 tylg set Systm+Objct
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22 atrv set ReEnt+rev
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23 rev set $00
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24 edition set 6
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25
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26 mod eom,name,tylg,atrv,start,size
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27
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28 * on-stack buffer to use
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29 org 0
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30 size equ .
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31
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32 name equ *
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33 fcs /Boot/
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34 fcb edition
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35
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36 start orcc #IntMasks ensure IRQ's are off.
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37
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38 pshs x,d save 4 bytes of junk
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39 R.D equ 1
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40 R.X equ 3
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41
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42 lda >MPI.Slct get current slot
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43 pshs a save off
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44 lda >PakSlot,pcr get multipak slot number
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45 bmi cont if >127, invalid slot number
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46 anda #$03 force it to be legal
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47 ldb #$11
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48 mul put it into both nibbles
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49 stb >MPI.Slct go to the desired slot
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50
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51 cont ldd #$0001 request one byte (will round up to 1 page)
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52 os9 F$SRqMem request the memory
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53 bcs L00AE exit on error
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54 * U is implicitely the buffer address to use
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55
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56 ldx #$0000 X=0: got to sector #$0000
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57 bsr GetSect load in LSN0, and point Y to the buffer
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58 bcs L00AE
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59
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60 ldd <DD.BSZ,u size of the bootstrap file
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61 std R.D,s save it on the stack (0,s is junk)
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62 ldx <DD.BT+1,u get starting sector of the bootstrap file
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63
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64 pshs x save the starting sector number
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65 ldd #$0100 one page of memory
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66 os9 F$SRtMem return the copy of LSN0 to free memory
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67
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68 ldd R.X,s get size of boot memory to request
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69 ifgt Level-1
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70 os9 F$BtMem ask for the boot memory
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71 else
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72 os9 F$SRqMem ask for the boot memory
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73 endc
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74 puls x restore the starting sector number
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75 bcs L00AE no memory: exit with error
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76
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77 stu R.X,s save start address of memory allocated
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78 std R.D,s and the size of the boot memory
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79 beq L00A7 if no memory allocated, exit
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80
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81 SectLp pshs x,d save sector #, size of boot
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82 bsr GetSect read one sector
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83 bcs L00AC if there's an error, exit
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84 puls x,d restor sector, size of boot
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85
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86 leau $0100,u go up one page in memory
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87 leax $01,x go to the next sector
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88 subd #$0100 take out one sector, need value in B, too.
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89 bhi SectLp loop until all sectors are read
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90
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91 L00A7 puls a
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92 sta >MPI.Slct
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93 clrb clear carry
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94 puls d return size of boot memory to user
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95 bra L00B0 and go exit
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96
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97 L00AC leas $04,s remove X,D off of stack
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98 L00AE puls a
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99 sta >MPI.Slct
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100 leas $02,s kill D off of the stack
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101
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102 L00B0 puls x restore start address of memory allocated
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103 * leas size,s remove the on-stack buffer
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104 clr >DPort stop the disk
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105 L00BA rts
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106
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107 * GetSect: read a sector off of the disk
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108 * Entry: X = sector number to read
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109 GetSect pshs d,x,y
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110 ldy >Address,pcr grab the device address
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111 tfr x,d move 16 bit LSN into 2 8-bit registers
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112 sta 2,y save HB LSN
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113 stb 1,y save LB LSN
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114 leax ,u get buffer address to write into
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115 clrb and start out at byte zero
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116
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117 ReadLp stb ,y save byte number
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118 lda 3,y grab the byte
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119 sta ,x+ save in the buffer
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120 incb go to the enxt byte
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121 bne ReadLp
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122 clrb no errors
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123 puls d,x,y,pc restore registers and return
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124
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125 ifgt Level-1
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126 Pad fill $39,$1D0-6-*
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127 endc
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128
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129 Address fdb $FF40 address of the device to boot from
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130 PakSlot fcb $01 multipak slot number
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131
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132 emod
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133 eom equ *
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134 end
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