make cursor visible immediately after printing a character, but for only 1 frame, to match C64 KERNAL behaviour

c64/kernal/blink_cursor.s

@@ -5,6 +5,19 @@
 	;; cursor_is_visible
 	;; colour_under_cursor
 
+show_cursor:
+	;; Set cursor as though it had just finished the off phase,
+	;; so that the call to blink_cursor paints it
+	lda #$00
+	sta cursor_blink_countdown
+	sta cursor_is_visible
+	jsr blink_cursor
+	;; Then set the timeout to 1 frame, so that the cursor
+	;; blinks under key repeat conditions, like on the original KERNAL
+	lda #$01
+	sta cursor_blink_countdown
+	rts
+	
 blink_cursor:
 	;; Is the cursor enabled?
 	bit cursor_blink_disable

c64/kernal/chrout.s

@@ -137,6 +137,9 @@ chrout_l1:
 	jmp screen_advance_to_next_line
 no_screen_advance_to_next_line:
 chrout_done:
+	;; Make cursor immediately visible
+	jsr show_cursor
+	
 	;; Restore X and Y, set carry to mark success on exit
 	pla
 	tay