Initial CommitHEADmain

1 files changed, 68 insertions, 0 deletions

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+;;; This thing is licensed under Creative Commons Zero v1.0 Universal, which essentially means
+;;; "Public Domain".  (You can do anything you want without asking for permission.)
+;;;
+;;; SPDX-License-Identifier: CC0-1.0
+;;;
+;;; To compile (You can get cl65 from <https://cc65.github.io/>)
+;;; $ cl65 -t c64 -C c64-asm.cfg -o flag.prg flag.s
+;;;
+;;; To run (You can get x64sc from <https://vice-emu.sourceforge.io/index.html>)
+;;; $ x64sc -autostart flag.prg
+;;;
+;;; I am not an expert with actual hardware C64, but this should be capable of running on one.  I am
+;;; of course not to be held responsible for any actual hardware damage.
+
+    .export __LOADADDR__: absolute = 1
+    .export __EXEHDR__: absolute = 1
+
+.segment "LOADADDR"
+    .word $0801
+    .org $0801
+
+.segment "EXEHDR"
+    ;; 1312 SYS<main>
+    .addr EmptyBasLine
+    .word 1312
+    .byte $9E
+    .byte _start / 1000 .mod 10 + '0'
+    .byte _start / 100  .mod 10 + '0'
+    .byte _start / 10   .mod 10 + '0'
+    .byte _start        .mod 10 + '0'
+    .byte 0
+EmptyBasLine:
+    .word 0
+
+.code
+_start:
+    lda #$00  ; Set border colour to black
+    sta $d020
+
+    lda #$03  ; Set text background to cyan
+    sta $d021 ; This lets us not draw the top&bottom bars :)
+
+    jsr $e544 ; Call the KERNAL internal clear screen routine
+              ; See <http://unusedino.de/ec64/technical/aay/c64/rome544.htm>
+
+    ldx #200
+loop:
+    ;; Full block character to each of the three bar text memory
+    lda #$e0
+    sta $400+5*40-1,x
+    sta $400+10*40-1,x
+    sta $400+15*40-1,x
+
+    ;; Pinkish colour to mid-top & mid-bot bar colour memory
+    lda #10
+    sta $d800+5*40-1,x
+    sta $d800+15*40-1,x
+
+    ;; Ditto for white in the middle bar
+    lda #1
+    sta $d800+10*40-1,x
+
+    dex
+    bne loop
+
+halt:
+    ;; Busy spinloop :(
+    jmp halt