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Add missing ORG
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michaelangel007
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README.md
109
README.md
@ -865,9 +865,9 @@ Recall we'll re-use our existing font drawing code `_DrawChar` at $0352:
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```assembly
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ORG $0352
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352: _DrawChar
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352: _DrawChar
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352:A2 00 LDX #0 ; next instruction is Self-Modifying!
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354:BD 00 00 _Font LDA $0000,X ; A = font[ offset + i ]
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354:BD 00 00 LoadFont LDA $0000,X ; A = font[ offset + i ]
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357:91 F5 STA (TmpLo),Y ; screen[col] = A
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359:18 CLC
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35A:A5 F6 LDA TmpHi
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@ -980,6 +980,7 @@ Let's fix it up to print the hex value of the current character we are inspectin
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; FUNC: DrawHexByte( c ) = $103C
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; PARAM: A = byte to print in hex
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103C: DrawHexByte
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103C:48 PHA ; save low nibble
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103D:6A ROR ; shift high nibble
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103E:6A ROR ; to low nibble
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@ -991,6 +992,7 @@ Let's fix it up to print the hex value of the current character we are inspectin
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; FUNC: DrawHexNib() = $1048
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; PARAM: A = nibble to print as hex char
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1048: DrawHexNib
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1048:29 0F AND #F ; base 16
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104A:AA TAX ;
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104B:20 66 03 JSR HgrToTmpPtr
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@ -998,7 +1000,7 @@ Let's fix it up to print the hex value of the current character we are inspectin
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1051:C8 INY ; IncCursorCol()
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1052:20 3B 03 JSR DrawCharCol
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1055:60 RTS
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ORG $358
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ORG $0358
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1058:30 31 32 33 NIB2HEX ASC "0123456789ABCDEF"
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105C:34 35 36 37
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1060:38 39 41 42
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@ -1034,9 +1036,9 @@ Let's use IncCursorCol() to automatically advance the cusor. We'll also add a s
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; Must start at every 8 scanlines.
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; OUTPUT: The Y-Register (cursor column) is automatically incremented.
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ORG $0310
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310 PrintChar
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310:20 3B 03 JSR DrawCharCol
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313:4C 70 03 JMP IncCursorCol
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0310: PrintChar
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0310:20 3B 03 JSR DrawCharCol
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0313:4C 70 03 JMP IncCursorCol
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```
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And the new code to draw a space before the hex num:
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@ -1050,6 +1052,7 @@ And the new code to draw a space before the hex num:
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; FUNC: DrawHexByte( c )
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; PARAM: A = byte to print in hex
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1041: DrawHexByte
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1041:48 PHA ; save low nibble
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1042:6A ROR ; shift high nibble
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1043:6A ROR ; to low nibble
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@ -1061,11 +1064,12 @@ And the new code to draw a space before the hex num:
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; FUNC: $1048 = DrawHexNib()
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; PARAM: A = nibble to print as hex char
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1048: DrawHexNib
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104D:29 0F AND #F ; base 16
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104F:AA TAX ;
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1050:BD 58 10 LDA $1058,X ; nibble to ASCII
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1050:BD 58 10 LDA NIB2HEX ,X ; nibble to ASCII
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1053:4C 10 03 JMP PrintChar ;
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1058:30 31 32 33 ASC "0123456789ABCDEF"
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1058:30 31 32 33 NIB2HEX ASC "0123456789ABCDEF"
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105C:34 35 36 37
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1060:38 39 41 42
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1064:43 44 45 46
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@ -1190,11 +1194,12 @@ Enter in:
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Now we can print a char at any location:
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```assembly
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ORG $1100
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1100:A9 41 LDA #41 ; A-register = char
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1102:A0 01 LDY #1 ; Y-register = col 1 (2nd column)
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1104:A2 02 LDX #2 ; X-register = row 2 (3rd row)
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1106:4C 20 03 JSR DrawCharColRow
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ORG $1100
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DrawXY
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1100:A9 41 LDA #41 ; A-register = char
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1102:A0 01 LDY #1 ; Y-register = col 1 (2nd column)
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1104:A2 02 LDX #2 ; X-register = row 2 (3rd row)
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1106:4C 20 03 JSR DrawCharColRow
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```
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Enter in:
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@ -1217,13 +1222,14 @@ We could map the X-register to the natural column (x-axis), and the Y-register t
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; FUNC: SetCursorColRowYX()
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; PARAM: Y = col
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; PARAM: X = row
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ORG $0379
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379:20 28 03 JSR SetCursorRow
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37C:18 CLC
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37D:98 TYA
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37E:65 F5 ADC $F5
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381:85 F5 STA $F5
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383:60 RTS
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ORG $0379
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379: SetCursorColRowYX
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379:20 28 03 JSR SetCursorRow
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37C:18 CLC
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37D:98 TYA
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37E:65 F5 ADC $F5
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381:85 F5 STA $F5
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383:60 RTS
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```
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Or are we stuck? Since we're using a function to calculate the destination address let's fix the order.
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@ -1233,17 +1239,17 @@ We'll need to change the `X` offset in SetCursorColRowXY() to `Y`;
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; FUNC: SetCursorColRow2( row ) = $0328
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; PARAM: Y = row
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; NOTES: Version 2 !
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328: ORG $0328
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328: SetCursorColRow2
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328:B9 00 64 LDA $6400,Y ; changed from: ,X
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32B:18 CLC
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32C:65 E5 ADC $E5
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32E:85 F5 STA $F5
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330:B9 18 64 LDA $6418,Y ; changed from: ,X
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333:18 CLC
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334:65 E6 ADC $E6
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336:85 F6 STA $F6
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338:60 RTS
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328: ORG $0328
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328: SetCursorColRow2
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328:B9 00 64 LDA HgrLoY,Y ; changed from: ,X
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32B:18 CLC
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32C:65 E5 ADC HgrLo
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32E:85 F5 STA TmpLo
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330:B9 18 64 LDA HgrHiY,Y ; changed from: ,X
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333:18 CLC
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334:65 E6 ADC HgrHi
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336:85 F6 STA TmpHi
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338:60 RTS
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```
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And change the low byte to add `X` instead:
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@ -1253,11 +1259,13 @@ And change the low byte to add `X` instead:
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; PARAM: X = col
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; PARAM: Y = row
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; NOTES: Version 2 !
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379:20 28 03 JSR SetCursorRow
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37C:18 CLC
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37D:88 TXA ; changed from: TYA
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37E:65 F5 ADC $F5
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381:85 F5 STA $F5
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ORG $0379
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379: SetCursorColRow2
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379:20 28 03 JSR SetCursorRow
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37C:18 CLC
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37D:88 TXA ; changed from: TYA
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37E:65 F5 ADC $F5
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381:85 F5 STA $F5
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383:60
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```
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@ -1269,18 +1277,19 @@ This is a little clunky but it is progress. Let's write the new SetCursorColRow(
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; PARAM: Y = row to draw at; $0 .. $17 (Rows 0 .. 23) (not modified)
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; NOTES: Version 3! X and Y is swapped from earlier version!
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; [$F5] = HgrLoY[ Y ] + ScreenLo + X
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ORG $0379
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379:86 F5 STX $F5
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37B:B9 00 64 LDA HgrLoY,Y ; HgrLoY[ row ]
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37E:18 CLC
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37F:65 E5 ADC $E5
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381:65 F5 ADC $F5 ; add column
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383:85 F5 STA $F5
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385:B9 18 64 LDA HgrHiY,Y ; HgrHiY[ row ]
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388:18 CLC
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389:65 E6 ADC $E6
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38B:85 F6 STA $F6
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38D:60 RTS
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ORG $0379
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379: SetCursorColRow
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379:86 F5 STX TmpLo
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37B:B9 00 64 LDA HgrLoY,Y ; HgrLoY[ row ]
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37E:18 CLC
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37F:65 E5 ADC HgrLo
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381:65 F5 ADC TmpLo ; add column
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383:85 F5 STA TmpLo
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385:B9 18 64 LDA HgrHiY,Y ; HgrHiY[ row ]
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388:18 CLC
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389:65 E6 ADC HgrHi
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38B:85 F6 STA TmpHi
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38D:60 RTS
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```
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Enter in:
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@ -1299,6 +1308,7 @@ Now that we have the basic print char working lets extend it to print a C-style
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; PARAM: X = High byte of string address
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; PARAM: Y = Low byte of string address
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ORG $038E
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38E: DrawString
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38E:84 F0 STY $F0
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390:86 F1 STX $F1
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392:A0 00 LDY #0
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@ -1314,6 +1324,8 @@ And our example to verify that it works:
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```assembly
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; FUNC: DemoDrawString()
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ORG $1200
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1200: DemoDrawString
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1200:A2 03 LDX #3 ; col = 3
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1202:A0 02 LDY #2 ; row = 2
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1204:20 79 03 JSR SetCursorColRow
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@ -1489,6 +1501,7 @@ And here is the assembly:
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; $6000.$63FF Font 7x8 Data
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; $6400.$642F HgrLoY, HgrHiY table for every 8 scanlines
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ORG $1300
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1300: CopyTextToHgr
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1300:A9 00 LDA #0
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1302:85 F3 STA row
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1304:85 E5 STA $E5
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