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Text File  |  2022-10-26  |  2KB  |  76 lines
  1. org 53100
  2. ;----------------------------------------------
  3. ;16k vdc ram - tool  by  klaus hegemann 1989
  4. ;----------------------------------------------
  5. :zero = 251
  6.  
  7.               jsr $aefd   ;vdc anfg.
  8.               jsr $a96b
  9.               lda $14
  10.               ldx $15
  11.               sta low+1
  12.               stx high+1
  13.               jsr zeroset
  14.               jsr $aefd   ;anfg.
  15.               jsr $a96b
  16.               lda $14
  17.               ldx $15
  18.               sta zero
  19.               stx zero+1
  20.               jsr $aefd   ;ende
  21.               jsr $b7eb
  22.               cpx #0
  23.               bne write
  24.  
  25. :read         jsr vdcget
  26.               ldy #0
  27.               sta (zero),y
  28.               jsr erhoeherer
  29.               jmp read
  30.  
  31. :write        ldy #0
  32.               lda (zero),y
  33.               ldy #31
  34.               jsr vdcput
  35.               jsr erhoeherer
  36.               jmp write
  37.  
  38. :erhoeherer   lda zero
  39.               clc
  40.               adc #1
  41.               sta zero
  42.               bcc noplus
  43.               inc zero+1
  44. :noplus       lda zero
  45.               cmp $14
  46.               bne load
  47.               lda zero+1
  48.               cmp $15
  49.               bne load
  50.               pla
  51.               pla
  52. :load         rts
  53.  
  54. :vdcget       ldy #31
  55.               sty $d600
  56. :gwait        bit $d600
  57.               bpl gwait
  58.               lda $d601
  59.               rts
  60. :zeroset      lda #80
  61.               ldy #1
  62.               jsr vdcput
  63.               lda #47
  64.               ldy #28
  65.               jsr vdcput
  66. :high         lda #0
  67.               ldy #18
  68.               jsr vdcput
  69. :low          lda #0
  70.               iny
  71. :vdcput       sty $d600
  72. :pwait        bit $d600
  73.               bpl pwait
  74.               sta $d601
  75.               rts
  76.