diff --git a/fac/Makefile b/fac/Makefile
index 4bc43d17..94d2c937 100644
--- a/fac/Makefile
+++ b/fac/Makefile
@@ -7,10 +7,10 @@ EMPTYDISK = ../empty_disk/empty.dsk
 
 all:	fac.dsk
 
-fac.dsk:	HELLO ADD
+fac.dsk:	HELLO SIN3
 	cp $(EMPTYDISK) fac.dsk
 	$(DOS33) -y fac.dsk SAVE A HELLO
-	$(DOS33) -y fac.dsk BSAVE -a 0xC00 ADD
+	$(DOS33) -y fac.dsk BSAVE -a 0xC00 SIN3
 
 
 ###
@@ -20,13 +20,13 @@ HELLO:	hello.bas
 
 ###
 
-ADD:	add.o
-	ld65 -o ADD add.o -C $(LINKERSCRIPTS)/apple2_c00.inc
+SIN3:	sin3.o
+	ld65 -o SIN3 sin3.o -C $(LINKERSCRIPTS)/apple2_c00.inc
 
-add.o:	add.s
-	ca65 -o add.o add.s -l add.lst
+sin3.o:	sin3.s
+	ca65 -o sin3.o sin3.s -l sin3.lst
 
 ###
 
 clean:	
-	rm -f *~ *.o *.lst ADD HELLO
+	rm -f *~ *.o *.lst SIN3 HELLO
diff --git a/fac/add.s b/fac/add.s
deleted file mode 100644
index f24d4446..00000000
--- a/fac/add.s
+++ /dev/null
@@ -1,5 +0,0 @@
-
-add_debut:
-
-end:
-	jmp	end
diff --git a/fac/hello.bas b/fac/hello.bas
index defcb97b..fd273ced 100644
--- a/fac/hello.bas
+++ b/fac/hello.bas
@@ -1,2 +1,2 @@
 5 HOME
-10 PRINT CHR$(4)"BRUN PLASMAG_TINY"
+10 PRINT CHR$(4)"BRUN SIN3"
diff --git a/fac/sin3.s b/fac/sin3.s
new file mode 100644
index 00000000..7568fc34
--- /dev/null
+++ b/fac/sin3.s
@@ -0,0 +1,173 @@
+; code to use the FAC (floating point accumulator)
+
+chkcom	=	$DEBE		; check for comma
+ptrget	=	$DFE3
+frmnum	=	$DD67		; evaluate expression, make sure is number
+FACEXP	=	$9D
+movmf	=	$EB2B		; move fac to mem: round FAC and store at Y:X
+movfm	=	$EAF9		; move mem to fac: unpack (Y:A) to FAC
+conupk	=	$E9E3
+fadd	=	$E7BE		; FAC = (Y:A)+FAC
+faddt	=	$E7C1		; FAC = ARG + FAC
+fadd_half =	$E7A0		; add 0.5 to FAC
+fsub	=	$E7A7		; FAC = (Y:A)-FAC
+fsubt	=	$E7AA		; FAC = ARG - FAC
+fzero	=	$E84E		; FAC = 0 (sets fac.sign and fac.exp)
+fcomplement =	$E89E		; twos complement of FAC
+fmult	=	$E97F		; FAC = (Y:A) * FAC
+fmultt	=	$E982		; FAC = ARG*FAC (!!! Z must be properly set)
+load_arg=	$E9E3		; unpack (Y:A) into ARG
+mul10	=	$EA39		; FAC=FAC*10
+div10	=	$EA55		; FAC=FAC/10
+div	=	$EA5E		; FAC=ARG/(Y:A)
+fdiv	=	$EA66		; FAC=(Y:A)/FAC
+fdivt	=	$EA69		; FAC=ARG/FAC (!!! Z must be properly set)
+; various round and store fac
+fac2arg	=	$EB63		; ARG = FAC
+sign	=	$EB82		; SGN(FAC) 1/0/-1
+float	=	$EB93		; signed value in A to FAC
+fcomp	=	$EBB2		; compare
+qint	=	$EBF2		; convert FAC to 32-bit int?
+int	=	$EC23		; INT(FAC) (clear fractional part)
+addafac	=	$ECD5		; add A to FAC (signed?)
+printfac=	$ED2E
+sqr	=	$EE8D		; FAC=sqrt(FAC) [actually does FAC^0.5
+fpwrt	=	$EE97		; FAC=ARG^FAC
+negop	=	$EED0		; FAC=-FAC
+exp	=	$EF09		; FAC = e^FAC
+; polynomial?
+rnd	=	$EFAE		; RAC = RND() random number
+cos	=	$EFEA
+sin	=	$EFF1
+tan	=	$F03A
+atn	=	$F09E
+
+; constants
+; one
+; poly coefficients?
+; sqrt(.5)
+; sqrt(2)
+; 0.5
+; -0.5
+; log(2)
+const_10=	$EA50	; 10
+; billion
+; 999,999,999
+; 99,999,999.9
+; log(e) to base(2)
+; polynomials for log
+; one
+; table of 32-bit powers of 10 +/- for some reason
+; pi/2
+pi_doub	=	$F06E	; 2*pi
+; 0.25 (quarter)
+
+
+ARG = $A5
+FAC = $9D
+
+; code uses: 5E/5F "index" in load arg from Y:A
+;	uses ARG (A5-AA) for argument
+;	uses FAC (9D-A2)
+
+
+; in memory, 5 bytes "packed"
+;	exponent, mantissa MSB, mantissa, mantissa, mantissa l.s.b
+;	top bit of exponent is sign (0 negative)
+;	so $84/$20/$00/$00/$00
+;	$84 = positive $4, subtract 1, so 2^3 = 8
+;	mantissa = 1.XX XX XX XX, in this case 1. (Sign)010 0000 = 1.25
+;	1.25*8 = 10
+
+; FAC also has sign byte at $A2
+
+
+; to make constants
+;	NEW
+;	A=10
+;	804L, should be 41 00 - 84 20 00 00 00
+;                        A    - 5-bytes for 10
+
+OURX	=	$FF
+
+sin3	=	$8000
+
+add_debut:
+
+	lda	#0
+	sta	OURX
+
+sin3_loop:
+	; 38+24*sin(3x)+16*sin(8x)
+	;     ours[i]=round(38.0+
+        ;                       24.0*sin(3.0*i*(PI*2.0/256.0))+
+        ;                       16.0*sin(8.0*i*(PI*2.0/256.0)));
+
+
+	lda	OURX
+	jsr	float		; FAC = X
+
+	lda	#<three_input
+	ldy	#>three_input
+	jsr	fmult
+	jsr	sin
+	lda	#<twenty_four
+	ldy	#>twenty_four
+	jsr	fmult
+
+	ldx	#<$8100
+	ldy	#>$8100
+	jsr	movmf			; save FAC to mem
+
+	lda	OURX
+	jsr	float		; FAC = X
+	lda	#<eight_input
+	ldy	#>eight_input
+	jsr	fmult
+	jsr	sin
+	lda	#<sixteen
+	ldy	#>sixteen
+	jsr	fmult
+
+	; add first sine
+	lda	#<$8100
+	ldy	#>$8100
+	jsr	fadd
+
+	; add 38
+	lda	#<thirty_eight
+	ldy	#>thirty_eight
+	jsr	fadd
+
+
+	jsr	qint
+
+	lda	FAC+4
+
+	ldx	OURX
+	sta	sin3,X
+
+	inc	OURX
+	bne	sin3_loop
+
+end:
+	jmp	end
+
+sixteen:
+	.byte	$85,$00,$00,$00,$00
+
+twenty_four:
+	.byte	$85,$40,$00,$00,$00
+
+thirty_eight:
+	.byte $86,$18,$00,$00,$00
+	; 2^5 = 32, 1.0011 0000 = 1/8+1/16
+
+three_input:
+	; 3*2*pi/256 = .0736310778
+	.byte $7d,$16,$cb,$e3,$f9
+
+eight_input:
+	; 8*2*pi/256 = .196349541
+	.byte $7E,$49,$0F,$DA,$9E
+