add some comments for jimmy <3

jacme/jimmy.s

@@ -2,24 +2,24 @@
 !source "basic-boot.s"
 +start_at $0900
 
-	sei				; no interrupts pls
+	sei					; no interrupts pls
 
-	ldx #$00		; Screen colours
+	ldx #$00			; screen colours
 	stx bdcol
 	ldx #$08
 	stx bgcol
 
-	jsr $e544		; clear screen
+	jsr $e544			; clear screen
 
-	lda #> message	; print message
+	lda #> message		; push the location of the text
-	pha
+	pha					;   to display onto the stack
 	lda #< message
 	pha
-	jsr print_string
+	jsr print_string	; call the actual print subroutine
 	pla
 	pla
 
-	;ldx #$01		; start triangle wave
+	;ldx #$01			; start triangle wave
 	;ldy #$11
 	;stx ch1_freq_hi
 	;sty ch1_freq_lo
@@ -27,31 +27,33 @@
 	;stx ch1_ctl
 
 .loop
-	inc bdcol
+	inc bdcol			; flashing gobbledygook garbage (scat)
 
-	lda inputb		; Scans the keyboard buffer
+	lda inputb			; Scans the keyboard buffer
-	cmp #$EF		; If user presses Space ($ef) then quit
+	cmp #$EF			; If user presses Space ($ef) then quit
 	bne .loop
 
-	ldx #$08		; kill sound
+	ldx #$08			; kill sound
 	stx ch1_ctl
 
 	rts
 
 print_string:
-	tsx
+	tsx					; load the stack pointer
+	inx					;   traverse upwards to our arguments
 	inx
 	inx
-	inx
+	lda stack, x		; copy the arguments on the stack
-	lda stack, x
+	sta PSL + 1			;   on top of the instruction that
-	sta PSL + 1
+	inx					;   needs to point to the text
-	inx
 	lda stack, x
 	sta PSL + 2
-
 	ldx #$00
-PSL	lda message, x
+
-	cmp #$0			; return on null terminator
+PSL	lda $0000, x		; this instruction's operand is
+						;   modified by the code above
+
+	cmp #$0				; return on null terminator
 	beq +
 	sta screen + rowlen, x
 	inx