� Colours by Interrupts
� By Tristram Mabbs
� for BBC Micro
(� (c) Acorn User April 1985
2:
<
� DLIs 50
FLine_Val=&260
P� Set up demonstration
Z� A=0 � 17 � 3
dA!DLIs=4*Line_Val
n"?(A+DLIs+2)=(((A/3)�7)+1)�&10 
x� A
�A!DLIs=�
�� 6
�� PROCsetdlis does the work
��setdlis(DLIs)
�#� Insert "L." into input buffer
�*FX138,0,76
�*FX138,0,46
�*FX138,0,13
��
�:
'� �setdlis(Data)
'+A%=135:Mode=((�(&FFF4)�&FF0000)/&10000)
'$� Code �assemble(0,&C000)
'.A=�assemble(0,Code)
'8A=�assemble(2,Code)
'BA=?Data+&A8:?Data=A
'L)Data?1=((Data?1)+((A � &F00)/&100)+6)
'V� Vec_Setup
'`�
'e:
'j� �assemble(Pass,Adr)
'tP%=Adr:[OPT Pass
'~\ Change the IRQ1 vector
'�.Vec_Setup SEI
'�+LDA&204:STA OldIrq:LDA&205:STA OldIrq+1
'�2LDA#NewIrq �&FF:STA&204:LDA#NewIrq/256:STA&205
'�CLI:RTS
'�.OldIrq BRK:BRK
'�\ New interrupt routine
'�&.NewIrq LDA&FC:PHA:TXA:PHA:TYA:PHA
'�LDA&FE4D:�&FE4E:�#&20
'�BNE DLI
'�LDA&FE4D:�&FE4E:�#2
'�BNE FSI
'�4.Irq_Exit PLA:TAY:PLA:TAX:PLA:STA&FC:JMP(OldIrq)
(\ Interrupts identified
(
$.FSI LDA&FE4E:�#&20:BEQ Irq_Exit
(LDA#0:STA ColCount
(\ DLI routine 
((.DLI STA&FE4D
(2LDX ColCount
(<ELDA Data+1,X:� Data,X:CMP#&FF:BNEP%+10:LDA#0:STAColCount:JMP Time
(FLDA Data+2,X:�#&F0
(PLSRA:LSRA:LSRA:LSRA:TAY
(ZLDA Data+2,X:�#&F:�#7
(d=]:� Mode+1 � �dzh,�DJi,�tni,�dzh,�dzh,�DJi,�dzh:[OPT Pass
(n\ Set the timer 
(x!.Time LDA&FE4B:�#&DF:STA&FE4B
(�LDX ColCount
(�/LDA Data,X:STA&FE48:INX:LDA Data,X:STA&FE49
(�INX:INX:STX ColCount
(�LDA#&A0:STA&FE4D:STA&FE4E
(�JMP Irq_Exit
(�\ Assorted data
(�.ColCount BRK
(�.Col2base EQUB0:EQUB&80
(�+.Col4base EQUB0:EQUB&20:EQUB&80:EQUB&A0
(�.Col16base BRK
(�\ The colour routines
(�
]:=P%-Adr
(�� 2 Colour
)
[OPT Pass
)PHA:TYA:�#1:TAY:PLA
)�A Col2base,Y
)"	LDX#7
),1.C2_loop STA&FE21:CLC:ADC#&10:DEX:BPL C2_loop
)6]
)@�
)J� 4 Colour
)T
[OPT Pass
)^PHA:TYA:�#3:TAY:PLA
)h�A Col4base,Y
)r	LDX#3
)|!STA&FE21:CLC:ADC#&10:STA&FE21
)�CLC:ADC#&30:STA&FE21
)�CLC:ADC#&10:STA&FE21
)�]
)��
)�:
)�� 16 Colour
)�
[OPT Pass
)�STA Col16base
)�TYA:ASLA:ASLA:ASLA:ASLA
)��A Col16base
)�STA&FE21
)�]
)��
)�:
)�� �dlisoff
*?&FE4E=&20:�
*
:
*
� �dlison
*?&FE4E=&A0:�
�

00000000  0d 00 0a 1b f4 20 43 6f  6c 6f 75 72 73 20 62 79  |..... Colours by|
00000010  20 49 6e 74 65 72 72 75  70 74 73 0d 00 14 17 f4  | Interrupts.....|
00000020  20 42 79 20 54 72 69 73  74 72 61 6d 20 4d 61 62  | By Tristram Mab|
00000030  62 73 0d 00 1e 13 f4 20  66 6f 72 20 42 42 43 20  |bs..... for BBC |
00000040  4d 69 63 72 6f 0d 00 28  1f f4 20 28 63 29 20 41  |Micro..(.. (c) A|
00000050  63 6f 72 6e 20 55 73 65  72 20 41 70 72 69 6c 20  |corn User April |
00000060  31 39 38 35 0d 00 32 05  3a 0d 00 3c 0d de 20 44  |1985..2.:..<.. D|
00000070  4c 49 73 20 35 30 0d 00  46 11 4c 69 6e 65 5f 56  |LIs 50..F.Line_V|
00000080  61 6c 3d 26 32 36 30 0d  00 50 1a f4 20 53 65 74  |al=&260..P.. Set|
00000090  20 75 70 20 64 65 6d 6f  6e 73 74 72 61 74 69 6f  | up demonstratio|
000000a0  6e 0d 00 5a 12 e3 20 41  3d 30 20 b8 20 31 37 20  |n..Z.. A=0 . 17 |
000000b0  88 20 33 0d 00 64 15 41  21 44 4c 49 73 3d 34 2a  |. 3..d.A!DLIs=4*|
000000c0  4c 69 6e 65 5f 56 61 6c  0d 00 6e 22 3f 28 41 2b  |Line_Val..n"?(A+|
000000d0  44 4c 49 73 2b 32 29 3d  28 28 28 41 2f 33 29 80  |DLIs+2)=(((A/3).|
000000e0  37 29 2b 31 29 84 26 31  30 20 0d 00 78 07 ed 20  |7)+1).&10 ..x.. |
000000f0  41 0d 00 82 0c 41 21 44  4c 49 73 3d b9 0d 00 8c  |A....A!DLIs=....|
00000100  07 eb 20 36 0d 00 96 1f  f4 20 50 52 4f 43 73 65  |.. 6..... PROCse|
00000110  74 64 6c 69 73 20 64 6f  65 73 20 74 68 65 20 77  |tdlis does the w|
00000120  6f 72 6b 0d 00 a0 12 f2  73 65 74 64 6c 69 73 28  |ork.....setdlis(|
00000130  44 4c 49 73 29 0d 00 aa  23 f4 20 49 6e 73 65 72  |DLIs)...#. Inser|
00000140  74 20 22 4c 2e 22 20 69  6e 74 6f 20 69 6e 70 75  |t "L." into inpu|
00000150  74 20 62 75 66 66 65 72  0d 00 b4 0f 2a 46 58 31  |t buffer....*FX1|
00000160  33 38 2c 30 2c 37 36 0d  00 be 0f 2a 46 58 31 33  |38,0,76....*FX13|
00000170  38 2c 30 2c 34 36 0d 00  c8 0f 2a 46 58 31 33 38  |8,0,46....*FX138|
00000180  2c 30 2c 31 33 0d 00 d2  05 e0 0d 00 dc 05 3a 0d  |,0,13.........:.|
00000190  27 10 14 dd 20 f2 73 65  74 64 6c 69 73 28 44 61  |'... .setdlis(Da|
000001a0  74 61 29 0d 27 1a 2b 41  25 3d 31 33 35 3a 4d 6f  |ta).'.+A%=135:Mo|
000001b0  64 65 3d 28 28 ba 28 26  46 46 46 34 29 80 26 46  |de=((.(&FFF4).&F|
000001c0  46 30 30 30 30 29 2f 26  31 30 30 30 30 29 0d 27  |F0000)/&10000).'|
000001d0  24 1d de 20 43 6f 64 65  20 a4 61 73 73 65 6d 62  |$.. Code .assemb|
000001e0  6c 65 28 30 2c 26 43 30  30 30 29 0d 27 2e 17 41  |le(0,&C000).'..A|
000001f0  3d a4 61 73 73 65 6d 62  6c 65 28 30 2c 43 6f 64  |=.assemble(0,Cod|
00000200  65 29 0d 27 38 17 41 3d  a4 61 73 73 65 6d 62 6c  |e).'8.A=.assembl|
00000210  65 28 32 2c 43 6f 64 65  29 0d 27 42 17 41 3d 3f  |e(2,Code).'B.A=?|
00000220  44 61 74 61 2b 26 41 38  3a 3f 44 61 74 61 3d 41  |Data+&A8:?Data=A|
00000230  0d 27 4c 29 44 61 74 61  3f 31 3d 28 28 44 61 74  |.'L)Data?1=((Dat|
00000240  61 3f 31 29 2b 28 28 41  20 80 20 26 46 30 30 29  |a?1)+((A . &F00)|
00000250  2f 26 31 30 30 29 2b 36  29 0d 27 56 0f d6 20 56  |/&100)+6).'V.. V|
00000260  65 63 5f 53 65 74 75 70  0d 27 60 05 e1 0d 27 65  |ec_Setup.'`...'e|
00000270  05 3a 0d 27 6a 19 dd 20  a4 61 73 73 65 6d 62 6c  |.:.'j.. .assembl|
00000280  65 28 50 61 73 73 2c 41  64 72 29 0d 27 74 14 50  |e(Pass,Adr).'t.P|
00000290  25 3d 41 64 72 3a 5b 4f  50 54 20 50 61 73 73 0d  |%=Adr:[OPT Pass.|
000002a0  27 7e 1c 5c 20 43 68 61  6e 67 65 20 74 68 65 20  |'~.\ Change the |
000002b0  49 52 51 31 20 76 65 63  74 6f 72 0d 27 88 12 2e  |IRQ1 vector.'...|
000002c0  56 65 63 5f 53 65 74 75  70 20 53 45 49 0d 27 92  |Vec_Setup SEI.'.|
000002d0  2b 4c 44 41 26 32 30 34  3a 53 54 41 20 4f 6c 64  |+LDA&204:STA Old|
000002e0  49 72 71 3a 4c 44 41 26  32 30 35 3a 53 54 41 20  |Irq:LDA&205:STA |
000002f0  4f 6c 64 49 72 71 2b 31  0d 27 9c 32 4c 44 41 23  |OldIrq+1.'.2LDA#|
00000300  4e 65 77 49 72 71 20 80  26 46 46 3a 53 54 41 26  |NewIrq .&FF:STA&|
00000310  32 30 34 3a 4c 44 41 23  4e 65 77 49 72 71 2f 32  |204:LDA#NewIrq/2|
00000320  35 36 3a 53 54 41 26 32  30 35 0d 27 a6 0b 43 4c  |56:STA&205.'..CL|
00000330  49 3a 52 54 53 0d 27 b0  13 2e 4f 6c 64 49 72 71  |I:RTS.'...OldIrq|
00000340  20 42 52 4b 3a 42 52 4b  0d 27 ba 1b 5c 20 4e 65  | BRK:BRK.'..\ Ne|
00000350  77 20 69 6e 74 65 72 72  75 70 74 20 72 6f 75 74  |w interrupt rout|
00000360  69 6e 65 0d 27 c4 26 2e  4e 65 77 49 72 71 20 4c  |ine.'.&.NewIrq L|
00000370  44 41 26 46 43 3a 50 48  41 3a 54 58 41 3a 50 48  |DA&FC:PHA:TXA:PH|
00000380  41 3a 54 59 41 3a 50 48  41 0d 27 ce 19 4c 44 41  |A:TYA:PHA.'..LDA|
00000390  26 46 45 34 44 3a 80 26  46 45 34 45 3a 80 23 26  |&FE4D:.&FE4E:.#&|
000003a0  32 30 0d 27 d8 0b 42 4e  45 20 44 4c 49 0d 27 e2  |20.'..BNE DLI.'.|
000003b0  17 4c 44 41 26 46 45 34  44 3a 80 26 46 45 34 45  |.LDA&FE4D:.&FE4E|
000003c0  3a 80 23 32 0d 27 ec 0b  42 4e 45 20 46 53 49 0d  |:.#2.'..BNE FSI.|
000003d0  27 f6 34 2e 49 72 71 5f  45 78 69 74 20 50 4c 41  |'.4.Irq_Exit PLA|
000003e0  3a 54 41 59 3a 50 4c 41  3a 54 41 58 3a 50 4c 41  |:TAY:PLA:TAX:PLA|
000003f0  3a 53 54 41 26 46 43 3a  4a 4d 50 28 4f 6c 64 49  |:STA&FC:JMP(OldI|
00000400  72 71 29 0d 28 00 1b 5c  20 49 6e 74 65 72 72 75  |rq).(..\ Interru|
00000410  70 74 73 20 69 64 65 6e  74 69 66 69 65 64 0d 28  |pts identified.(|
00000420  0a 24 2e 46 53 49 20 4c  44 41 26 46 45 34 45 3a  |.$.FSI LDA&FE4E:|
00000430  80 23 26 32 30 3a 42 45  51 20 49 72 71 5f 45 78  |.#&20:BEQ Irq_Ex|
00000440  69 74 0d 28 14 16 4c 44  41 23 30 3a 53 54 41 20  |it.(..LDA#0:STA |
00000450  43 6f 6c 43 6f 75 6e 74  0d 28 1e 12 5c 20 44 4c  |ColCount.(..\ DL|
00000460  49 20 72 6f 75 74 69 6e  65 20 0d 28 28 11 2e 44  |I routine .((..D|
00000470  4c 49 20 53 54 41 26 46  45 34 44 0d 28 32 10 4c  |LI STA&FE4D.(2.L|
00000480  44 58 20 43 6f 6c 43 6f  75 6e 74 0d 28 3c 45 4c  |DX ColCount.(<EL|
00000490  44 41 20 44 61 74 61 2b  31 2c 58 3a 80 20 44 61  |DA Data+1,X:. Da|
000004a0  74 61 2c 58 3a 43 4d 50  23 26 46 46 3a 42 4e 45  |ta,X:CMP#&FF:BNE|
000004b0  50 25 2b 31 30 3a 4c 44  41 23 30 3a 53 54 41 43  |P%+10:LDA#0:STAC|
000004c0  6f 6c 43 6f 75 6e 74 3a  4a 4d 50 20 54 69 6d 65  |olCount:JMP Time|
000004d0  0d 28 46 16 4c 44 41 20  44 61 74 61 2b 32 2c 58  |.(F.LDA Data+2,X|
000004e0  3a 80 23 26 46 30 0d 28  50 1b 4c 53 52 41 3a 4c  |:.#&F0.(P.LSRA:L|
000004f0  53 52 41 3a 4c 53 52 41  3a 4c 53 52 41 3a 54 41  |SRA:LSRA:LSRA:TA|
00000500  59 0d 28 5a 19 4c 44 41  20 44 61 74 61 2b 32 2c  |Y.(Z.LDA Data+2,|
00000510  58 3a 80 23 26 46 3a 82  23 37 0d 28 64 3d 5d 3a  |X:.#&F:.#7.(d=]:|
00000520  ee 20 4d 6f 64 65 2b 31  20 e4 20 8d 64 7a 68 2c  |. Mode+1 . .dzh,|
00000530  8d 44 4a 69 2c 8d 74 6e  69 2c 8d 64 7a 68 2c 8d  |.DJi,.tni,.dzh,.|
00000540  64 7a 68 2c 8d 44 4a 69  2c 8d 64 7a 68 3a 5b 4f  |dzh,.DJi,.dzh:[O|
00000550  50 54 20 50 61 73 73 0d  28 6e 14 5c 20 53 65 74  |PT Pass.(n.\ Set|
00000560  20 74 68 65 20 74 69 6d  65 72 20 0d 28 78 21 2e  | the timer .(x!.|
00000570  54 69 6d 65 20 4c 44 41  26 46 45 34 42 3a 80 23  |Time LDA&FE4B:.#|
00000580  26 44 46 3a 53 54 41 26  46 45 34 42 0d 28 82 10  |&DF:STA&FE4B.(..|
00000590  4c 44 58 20 43 6f 6c 43  6f 75 6e 74 0d 28 8c 2f  |LDX ColCount.(./|
000005a0  4c 44 41 20 44 61 74 61  2c 58 3a 53 54 41 26 46  |LDA Data,X:STA&F|
000005b0  45 34 38 3a 49 4e 58 3a  4c 44 41 20 44 61 74 61  |E48:INX:LDA Data|
000005c0  2c 58 3a 53 54 41 26 46  45 34 39 0d 28 96 18 49  |,X:STA&FE49.(..I|
000005d0  4e 58 3a 49 4e 58 3a 53  54 58 20 43 6f 6c 43 6f  |NX:INX:STX ColCo|
000005e0  75 6e 74 0d 28 a0 1d 4c  44 41 23 26 41 30 3a 53  |unt.(..LDA#&A0:S|
000005f0  54 41 26 46 45 34 44 3a  53 54 41 26 46 45 34 45  |TA&FE4D:STA&FE4E|
00000600  0d 28 aa 10 4a 4d 50 20  49 72 71 5f 45 78 69 74  |.(..JMP Irq_Exit|
00000610  0d 28 b4 13 5c 20 41 73  73 6f 72 74 65 64 20 64  |.(..\ Assorted d|
00000620  61 74 61 0d 28 be 11 2e  43 6f 6c 43 6f 75 6e 74  |ata.(...ColCount|
00000630  20 42 52 4b 0d 28 c8 1b  2e 43 6f 6c 32 62 61 73  | BRK.(...Col2bas|
00000640  65 20 45 51 55 42 30 3a  45 51 55 42 26 38 30 0d  |e EQUB0:EQUB&80.|
00000650  28 d2 2b 2e 43 6f 6c 34  62 61 73 65 20 45 51 55  |(.+.Col4base EQU|
00000660  42 30 3a 45 51 55 42 26  32 30 3a 45 51 55 42 26  |B0:EQUB&20:EQUB&|
00000670  38 30 3a 45 51 55 42 26  41 30 0d 28 dc 12 2e 43  |80:EQUB&A0.(...C|
00000680  6f 6c 31 36 62 61 73 65  20 42 52 4b 0d 28 e6 19  |ol16base BRK.(..|
00000690  5c 20 54 68 65 20 63 6f  6c 6f 75 72 20 72 6f 75  |\ The colour rou|
000006a0  74 69 6e 65 73 0d 28 f0  0d 5d 3a 3d 50 25 2d 41  |tines.(..]:=P%-A|
000006b0  64 72 0d 28 fa 0e f4 20  32 20 43 6f 6c 6f 75 72  |dr.(... 2 Colour|
000006c0  0d 29 04 0d 5b 4f 50 54  20 50 61 73 73 0d 29 0e  |.)..[OPT Pass.).|
000006d0  17 50 48 41 3a 54 59 41  3a 80 23 31 3a 54 41 59  |.PHA:TYA:.#1:TAY|
000006e0  3a 50 4c 41 0d 29 18 11  84 41 20 43 6f 6c 32 62  |:PLA.)...A Col2b|
000006f0  61 73 65 2c 59 0d 29 22  09 4c 44 58 23 37 0d 29  |ase,Y.)".LDX#7.)|
00000700  2c 31 2e 43 32 5f 6c 6f  6f 70 20 53 54 41 26 46  |,1.C2_loop STA&F|
00000710  45 32 31 3a 43 4c 43 3a  41 44 43 23 26 31 30 3a  |E21:CLC:ADC#&10:|
00000720  44 45 58 3a 42 50 4c 20  43 32 5f 6c 6f 6f 70 0d  |DEX:BPL C2_loop.|
00000730  29 36 05 5d 0d 29 40 05  f8 0d 29 4a 0e f4 20 34  |)6.].)@...)J.. 4|
00000740  20 43 6f 6c 6f 75 72 0d  29 54 0d 5b 4f 50 54 20  | Colour.)T.[OPT |
00000750  50 61 73 73 0d 29 5e 17  50 48 41 3a 54 59 41 3a  |Pass.)^.PHA:TYA:|
00000760  80 23 33 3a 54 41 59 3a  50 4c 41 0d 29 68 11 84  |.#3:TAY:PLA.)h..|
00000770  41 20 43 6f 6c 34 62 61  73 65 2c 59 0d 29 72 09  |A Col4base,Y.)r.|
00000780  4c 44 58 23 33 0d 29 7c  21 53 54 41 26 46 45 32  |LDX#3.)|!STA&FE2|
00000790  31 3a 43 4c 43 3a 41 44  43 23 26 31 30 3a 53 54  |1:CLC:ADC#&10:ST|
000007a0  41 26 46 45 32 31 0d 29  86 18 43 4c 43 3a 41 44  |A&FE21.)..CLC:AD|
000007b0  43 23 26 33 30 3a 53 54  41 26 46 45 32 31 0d 29  |C#&30:STA&FE21.)|
000007c0  90 18 43 4c 43 3a 41 44  43 23 26 31 30 3a 53 54  |..CLC:ADC#&10:ST|
000007d0  41 26 46 45 32 31 0d 29  9a 05 5d 0d 29 a4 05 f8  |A&FE21.)..].)...|
000007e0  0d 29 a9 05 3a 0d 29 ae  0f f4 20 31 36 20 43 6f  |.)..:.)... 16 Co|
000007f0  6c 6f 75 72 0d 29 b8 0d  5b 4f 50 54 20 50 61 73  |lour.)..[OPT Pas|
00000800  73 0d 29 c2 11 53 54 41  20 43 6f 6c 31 36 62 61  |s.)..STA Col16ba|
00000810  73 65 0d 29 cc 1b 54 59  41 3a 41 53 4c 41 3a 41  |se.)..TYA:ASLA:A|
00000820  53 4c 41 3a 41 53 4c 41  3a 41 53 4c 41 0d 29 d6  |SLA:ASLA:ASLA.).|
00000830  10 84 41 20 43 6f 6c 31  36 62 61 73 65 0d 29 e0  |..A Col16base.).|
00000840  0c 53 54 41 26 46 45 32  31 0d 29 ea 05 5d 0d 29  |.STA&FE21.)..].)|
00000850  f4 05 f8 0d 29 f9 05 3a  0d 29 fe 0e dd 20 f2 64  |....)..:.)... .d|
00000860  6c 69 73 6f 66 66 0d 2a  08 10 3f 26 46 45 34 45  |lisoff.*..?&FE4E|
00000870  3d 26 32 30 3a e1 0d 2a  0d 05 3a 0d 2a 12 0d dd  |=&20:..*..:.*...|
00000880  20 f2 64 6c 69 73 6f 6e  0d 2a 1c 10 3f 26 46 45  | .dlison.*..?&FE|
00000890  34 45 3d 26 41 30 3a e1  0d ff                    |4E=&A0:...|
0000089a