diff --git a/interlace_demo/Makefile b/interlace_demo/Makefile
index b60fdff3..2f0a2991 100644
--- a/interlace_demo/Makefile
+++ b/interlace_demo/Makefile
@@ -7,11 +7,11 @@ PNG_TO_40x48D = ../gr-utils/png_to_40x48d
 
 all:	interlace.dsk
 
-interlace.dsk:	INTERLACE RASTERBARS SPRITES HELLO RASTERBARS_SOUND
+interlace.dsk:	INTERLACE RASTERBARS HELLO RASTERBARS_SOUND #SPRITES
 	$(DOS33) -y interlace.dsk SAVE A HELLO
 	$(DOS33) -y interlace.dsk BSAVE -a 0x1000 INTERLACE
 	$(DOS33) -y interlace.dsk BSAVE -a 0x1000 RASTERBARS
-	$(DOS33) -y interlace.dsk BSAVE -a 0x1000 SPRITES
+#	$(DOS33) -y interlace.dsk BSAVE -a 0x1000 SPRITES
 	$(DOS33) -y interlace.dsk BSAVE -a 0x1000 RASTERBARS_SOUND
 
 ####
@@ -45,7 +45,7 @@ RASTERBARS_SOUND:	rasterbars_sound.o
 
 rasterbars_sound.o:	rasterbars_sound.s gr_copy.s \
 	rasterbars_screen.s rasterbars_table.s movement_table.s rb_bg.inc \
-	pt3_lib_ci.s pt3_lib_init.s pt3_lib_mockingboard.s
+	pt3_lib_core.s pt3_lib_init.s pt3_lib_mockingboard.s pt3_write_frame.s
 	ca65 -o rasterbars_sound.o rasterbars_sound.s -l rasterbars_sound.lst
 
 
diff --git a/interlace_demo/pt3_lib_ci.s b/interlace_demo/pt3_lib_ci.s.old
similarity index 100%
rename from interlace_demo/pt3_lib_ci.s
rename to interlace_demo/pt3_lib_ci.s.old
diff --git a/interlace_demo/pt3_lib_core.s b/interlace_demo/pt3_lib_core.s
index a119c1d5..23fab8a6 100644
--- a/interlace_demo/pt3_lib_core.s
+++ b/interlace_demo/pt3_lib_core.s
@@ -1466,7 +1466,7 @@ not_done:
 	; update pattern or line if necessary
 	; then calculate the values for the next frame
 
-	; 8+355=363
+	; 8+367=375
 
 	;==========================
 	; pattern done early!
@@ -1558,13 +1558,15 @@ next_pattern:
 
 .endif
 
+
+
 	;======================================
 	; do frame
 	;======================================
 	; ????? FIXME/calculate note
 	;
 
-	; 9+ 184 +    36+11+18+30+18+49 = 355
+	; 9+ 196 +    36+11+18+30+18+49 = 367
 
 do_frame:
 	; AY-3-8910 register summary
@@ -1586,13 +1588,13 @@ do_frame:
 								;	9
 
 	;;ldx	#(NOTE_STRUCT_SIZE*0)	; Note A
-	jsr	calculate_note						; 6+54
+	jsr	calculate_note						; 6+58
 	ldx	#(NOTE_STRUCT_SIZE*1)	; Note B			; 2
-	jsr	calculate_note						; 6+54
+	jsr	calculate_note						; 6+58
 	ldx	#(NOTE_STRUCT_SIZE*2)	; Note C			; 2
-	jsr	calculate_note						; 6+54
+	jsr	calculate_note						; 6+58
 								;=============
-								; FIXME 184
+								; FIXME 196
 
 	; Note, we assume 1MHz timings, adjust pt3 as needed
 
@@ -1675,8 +1677,8 @@ pt3_envelope_slide_h_smc:
 
 	;========================
 	; Envelope shape
-	; same=18
-	; diff=14+[4]
+	; same=11 + 7 = 18
+	; diff=11 + [4] + 3 = 18
 
 pt3_envelope_type_smc:
 	lda	#$d1							; 2
@@ -1684,6 +1686,8 @@ pt3_envelope_type_old_smc:
 	cmp	#$d1							; 2
 	sta	pt3_envelope_type_old_smc+1; copy old to new		; 4
 	bne	envelope_diff_waste					; 3
+								;============
+								;        11
 envelope_same:
 									;-1
 	lda	#$ff			; if same, store $ff		; 2
@@ -1702,9 +1706,9 @@ envelope_diff:
 	;==============================
 
 	; if envelope delay 0, skip
-	;	= 5+6 + [38] = 49
+	;	= 5+ [38]  + 6 = 49
 	; else if envelope delay 1, skip
-	;	= 5+8+6 + [30] = 49
+	;	= 5+8+[30] + 6 = 49
 	; else
 	;	= 5+8+30+6 = 49
 
@@ -1712,6 +1716,9 @@ pt3_envelope_delay_smc:
 	lda	#$d1							; 2
 	beq	done_do_frame_x		; assume can't be negative?	; 3
 					; do this if envelope_delay>0
+									;====
+									; 5
+
 									; -1
 	dec	pt3_envelope_delay_smc+1				; 6
 	bne	done_do_frame_y						; 3
diff --git a/interlace_demo/pt3_write_frame.s b/interlace_demo/pt3_write_frame.s
new file mode 100644
index 00000000..79894d77
--- /dev/null
+++ b/interlace_demo/pt3_write_frame.s
@@ -0,0 +1,97 @@
+
+.align	$100
+
+
+
+
+	;====================================
+	; mb_write_frame
+	;====================================
+	; cycle counted
+
+	; 2 + 13*(70) + 74 + 5  = 991
+
+mb_write_frame:
+
+	ldx	#0		; set up reg count			; 2
+								;============
+								;	  2
+
+	;==================================
+	; loop through the 14 registers
+	; reading the value, then write out
+	;==================================
+
+mb_write_loop:
+	;=============================
+	; not r13 	-- 4+5+28+26+7		= 70
+	; r13, not ff	-- 4+5+ 4 +28+26+7	= 74
+	; r13 is ff 	-- 4+5+3+1=[61] 	= 74
+
+
+	lda	AY_REGISTERS,X	; load register value			; 4
+
+	; special case R13.  If it is 0xff, then don't update
+	; otherwise might spuriously reset the envelope settings
+
+	cpx	#13							; 2
+	bne	mb_not_13						; 3
+
+									; -1
+	cmp	#$ff							; 2
+	bne	mb_not_13						; 3
+									; -1
+
+
+	; delay 61
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	inc	TEMP		; 5
+	lda	TEMP		; 3
+	jmp	mb_skip_13	; 3
+
+mb_not_13:
+
+
+	; address
+	stx	MOCK_6522_ORA1		; put address on PA1		; 4
+	stx	MOCK_6522_ORA2		; put address on PA2		; 4
+	ldy	#MOCK_AY_LATCH_ADDR	; latch_address for PB1		; 2
+	sty	MOCK_6522_ORB1		; latch_address on PB1          ; 4
+	sty	MOCK_6522_ORB2		; latch_address on PB2		; 4
+	ldy	#MOCK_AY_INACTIVE	; go inactive			; 2
+	sty	MOCK_6522_ORB1						; 4
+	sty	MOCK_6522_ORB2						; 4
+								;==========
+								;	28
+        ; value
+	sta	MOCK_6522_ORA1		; put value on PA1		; 4
+	sta	MOCK_6522_ORA2		; put value on PA2		; 4
+	lda	#MOCK_AY_WRITE		;				; 2
+	sta	MOCK_6522_ORB1		; write on PB1			; 4
+	sta	MOCK_6522_ORB2		; write on PB2			; 4
+	sty	MOCK_6522_ORB1						; 4
+	sty	MOCK_6522_ORB2						; 4
+								;===========
+								; 	26
+mb_no_write:
+	inx				; point to next register	; 2
+	cpx	#14			; if 14 we're done		; 2
+	bmi	mb_write_loop		; otherwise, loop		; 3
+								;============
+								; 	7
+mb_skip_13:
+									; -1
+	rts								; 6
+
+
+pt3_loop_smc:
+	.byte $0,$0
diff --git a/interlace_demo/rasterbars_sound.s b/interlace_demo/rasterbars_sound.s
index f57f3157..62fbae1e 100644
--- a/interlace_demo/rasterbars_sound.s
+++ b/interlace_demo/rasterbars_sound.s
@@ -178,10 +178,10 @@ display_loop:
 	; -582	-- erase     22+4*(8+6+126) = 582
 	; -696  -- move+draw 4*(16+26+6+126) = 696
 	;  -10  -- keypress
-	; -369	-- calc values
+	; -381	-- calc values
 	; -997  -- mockingboard out
 	;=======
-	; 1896
+	; 1884	2881 2265
 
 pad_time:
 
@@ -211,7 +211,7 @@ pad_time:
 
 	; erase yellow
 
-	lda	yellow_x				; 4
+	lda	yellow_x			; 4
 	and	#$7f				; 2
 	tax					; 2
 
@@ -354,7 +354,7 @@ pad_time:
 	;============================
 
 
-	jsr	pt3_make_frame		; 6+363	= 369
+	jsr	pt3_make_frame		; 6+375	= 381
 	jsr	mb_write_frame		; 6+991 = 997
 
 
@@ -362,12 +362,16 @@ pad_time:
 	; WAIT for VBLANK to finish
 	;============================
 
-	; Try X=125 Y=3 cycles=1894R2
+	; Try X=124 Y=3 cycles=1879R5
 
+	lda	TEMP
 	nop
 
+	; Try X=2 Y=180 cycles=2881
+	; Try X=112 Y=4 cycles=2265
+
 	ldy	#3							; 2
-loop1:	ldx	#125							; 2
+loop1:	ldx	#124							; 2
 loop2:	dex								; 2
 	bne	loop2							; 2nt/3
 	dey								; 2
@@ -460,10 +464,6 @@ smc_raster_color1_2:
 .include "gr_offsets.s"
 .include "gr_unrle.s"
 
-; dummy value for pt3 routines
-pt3_loop_smc:
-.byte	$00,$00
-
 .align $100
 .include "rasterbars_table.s"
 .include "movement_table.s"
@@ -484,6 +484,7 @@ blue_x:		.byte $40
 .include "pt3_lib_core.s"
 .include "pt3_lib_init.s"
 .include "pt3_lib_mockingboard.s"
+.include "pt3_write_frame.s"
 
 ;=============
 ; include song