75 lines
1.1 KiB
ArmAsm
75 lines
1.1 KiB
ArmAsm
*= $06
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hgr_ptr .ds 2
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FIRST_CHAR_OF_SCREEN .ds 1
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FRAME_COUNT .ds 1
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*= $5000
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start_set
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jsr set_hires
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jsr driver
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jsr set_text
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jmp forever
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rts
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brk
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driver
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lda #$00
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sta FIRST_CHAR_OF_SCREEN
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lda #64
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sta FRAME_COUNT
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page_loop
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jsr page
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dec FRAME_COUNT
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bne page_loop
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rts
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forever
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jmp forever
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; os memory map
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KEYBOARD = $c000
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KBDSTROBE = $c010
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CLRTEXT = $c050
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SETTEXT = $c051
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CLRMIXED = $c052
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SETMIXED = $c053
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TXTPAGE1 = $c054
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TXTPAGE2 = $c055
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CLRHIRES = $c056
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SETHIRES = $c057
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set_hires bit CLRTEXT ; start with HGR page 1, full screen
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bit CLRMIXED
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bit TXTPAGE1
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bit SETHIRES
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rts
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set_text bit SETTEXT
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bit CLRMIXED
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bit TXTPAGE1
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bit CLRHIRES
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rts
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*= $5074
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page
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; set hires page 1 only
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lda #$20
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sta setscr_smc+2
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lda frame_count
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ldy #0
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lda #$ff
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setscr_smc sta $ff00,y ; 4
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iny ; 2
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bne setscr_smc ; 4 = 10 * 256
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inc setscr_smc+2 ; 6
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ldx setscr_smc+2 ; 6
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cpx #$40 ; 2
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bcc setscr_smc ; 4
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rts ; (18 + 10*256) * 32 = 82496
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brk
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