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base:opening_the_top_bottom_borders [2015-04-17 04:33] (current)
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 +==== Opening the top and bottom borders ====
 +This is a clever trick for you to try on the C64. Demos in the 1980's and 1990's and probably still today use the opened borders technique. I am going to show you how to do a simple border opening technique in ACME crossassembler format. ​
 +<​code>​
 +;Opening the top + bottom borders
 +;inside an IRQ interrupt player
  
 +         !to "​borders.prg"​
 +         
 +         * = $0810 ;SYS 2064 to run it
 +         sei
 +         lda #$02
 +         sta $d020
 +         lda #$00
 +         sta $d021
 +         lda #<irq1
 +         sta $314
 +         lda #>irq1
 +         sta $315
 +         lda #$7f
 +         sta $dc0d
 +         lda #$1b
 +         sta $d011
 +         lda #$01
 +         sta $d01a
 +         cli
 +         jmp *
 +irq1:    inc $d019
 +         lda #$00
 +         sta $d012
 +         lda #$00
 +         sta $d011
 +         lda #<irq2
 +         sta $314
 +         lda #>irq2
 +         sta $315
 +         jmp $ea7e
 +irq2:    inc $d019
 +         lda #$fa
 +         sta $d012
 +         lda #$1b ;If you want to display a bitmap pic, use #$3b instead
 +         sta $d011
 +         lda #<irq1
 +         sta $314
 +         lda #>irq1
 +         sta $315
 +         jmp $ea7e
 +</​code>​
base/opening_the_top_bottom_borders.txt ยท Last modified: 2015-04-17 04:33 (external edit)