meh

jacme/basic-boot.s

@@ -0,0 +1,24 @@
+; A BASIC booter, encodes `10 SYS <address>`.
+; Macrofied from http://www.pouet.net/topic.php?which=6541
+
+!macro start_at .address {
+  * = $0801
+  !byte $0c,$08,$00,$00,$9e
+  !if .address >= 10000 { !byte 48 + ((.address / 10000) % 10) }
+  !if .address >=  1000 { !byte 48 + ((.address /  1000) % 10) }
+  !if .address >=   100 { !byte 48 + ((.address /   100) % 10) }
+  !if .address >=    10 { !byte 48 + ((.address /    10) % 10) }
+  !byte $30 + (.address % 10), $00, $00, $00
+  * = .address
+}
+
+; A cooler example is to write
+;
+;   10 SYS <address>: REM <backspaces>Your comment
+;
+; When the user types LIST, he will just see
+;
+;   10 Your comment
+;
+; but still be able to run it.
+; For this, see http://codebase64.org/doku.php?id=base:acme-macro-tut

jacme/constants.s

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+stack = $0100
+
+screen = $0400
+rowlen = $28
+
+bdcol = $D020
+bgcol = $D021
+
+inputa = $DC00
+inputb = $DC01
+
+ch1_freq_lo = $D400
+ch1_freq_hi = $D401 
+ch1_duty_lo = $D402
+ch1_duty_hi = $D403
+ch1_ctl     = $D404
+ch1_env_ad  = $D405
+ch1_env_sr  = $D406

jacme/jimmy.s

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+!source "constants.s"
+!source "basic-boot.s"
++start_at $0900
+
+	sei				; no interrupts pls
+
+	ldx #$00		; Screen colours
+	stx bdcol
+	ldx #$08
+	stx bgcol
+
+	jsr $e544		; clear screen
+	
+	;lda < message		; print message
+	;pha
+	;lda > message
+	;pha
+	jsr print_string
+	;pla
+	;pla
+
+	ldx #$01		; start triangle wave
+	ldy #$11
+	stx ch1_freq_hi
+	sty ch1_freq_lo
+	ldx #$11
+	stx ch1_ctl
+	
+.loop
+	inc bdcol
+
+	lda inputb		; Scans the keyboard buffer
+	cmp #$EF		; If user presses Space ($ef) then quit
+	bne .loop
+
+	ldx #$08		; kill sound
+	stx ch1_ctl
+
+	rts
+
+print_string:
+	;lda	message
+	;sta PSL + 2
+	;lda > message
+	;sta PSL + 1
+	
+	ldx #$00
+PSL	lda message, x
+	cmp #$0			; return on null terminator
+	beq +
+	sta screen + rowlen, x
+	inx
+	jmp PSL
++	rts
+
+message !scr "welcome to scat os", 0