diff --git a/fix16.tal b/fix16.tal
index defb2f8..efc10bd 100644
--- a/fix16.tal
+++ b/fix16.tal
@@ -174,6 +174,9 @@
 @x16-gt   ( x* y* ->  x<y^ ) x16-cmp #01 EQU JMP2r
 @x16-gteq ( x* y* ->  x<y^ ) x16-cmp [ #ff NEQ ] JMP2r
 
+@unsigned-min ( x* y* -> min* )
+    LTH2k JMP SWP2 POP2 JMP2r
+
 @x16-min ( x* y* -> min[x, y]* )
     OVR2 OVR2 x16-lt JMP SWP2 POP2 JMP2r
 
@@ -192,50 +195,24 @@
 @x16-negate ( x* -> -x* )
     #0000 SWP2 SUB2 JMP2r
 
-( @x16-mul ( x* y* -> xy* )
-         DUP #00 EQU ?&rhs-whole
-    SWP2 DUP #00 EQU ?&rhs-whole
-    ,&y3 STR ,&y1 STR ,&x3 STR ,&x1 STR
-    LIT2 &x2 00 &x3 00 LIT2 &y2 00 &y3 00 MUL2 #08 SFT2
-    LIT2 &x0 00 &x1 00 ,&y2 LDR2          MUL2          ADD2
-    ,&x2 LDR2          LIT2 &y0 00 &y1 00 MUL2          ADD2
-    ,&x0 LDR2          ,&y0 LDR2 MUL2 #80 SFT2 ADD2 JMP2r
-    &rhs-whole #08 SFT2 MUL2 JMP2r )
-
-( @x16-div ( x* y* -> x/y* )
-    DIV2k STH2k       ( x y x/y  {x/y}         )
-    LITr 80 SFT2r     ( x y x/y  {div=(x/y)<<8 )
-    OVR2 STH2         ( x y x/y  {y div}       )
-    MUL2 SUB2         ( x%y      {y div}       )
-    STH2r LIT2r 0100  ( x%y y    {0100 div}    )
-    ( we know x%y < y, so start right-shifting y )
-    &loop
-        ORAk #00 EQU ?&done
-        #01 SFT2 LITr 01 SFT2r  ( rem yi    {shifti div} )
-        LTH2k ?&loop            ( rem yi    {shifti div} )
-        SWP2 OVR2 SUB2 SWP2     ( rem-yi yi {shifti div} )
-        DUP2r ROT2r ADD2r SWP2r ( rem-yi yi {shifti div+shifti} )
-        !&loop                  ( rem-yi yi {shifti div+shifti} )
-    &done
-        POP2 POP2         ( {shiftk div} )
-        POP2r STH2r JMP2r ( div ) )
-
 @x16-mul ( x* y* -- xy* )
     ;x16-mul-unsigned !x16-signed-op
 
 @x16-mul-unsigned ( x* y* -- xy* )
          DUP #00 EQU ?x16-mul-unsigned-rhs-whole
     SWP2 DUP #00 EQU ?x16-mul-unsigned-rhs-whole
-    ,&al STR ,&ah STR ,&bl STR ,&bh STR
-    LIT2 &a1 00 &al 00  LIT2 &b1 00 &bl 00  MUL2 #08 SFT2
-    LIT2 &a2 00 &ah 00  ,&b1 LDR2           MUL2          ADD2
-    ,&a1 LDR2           LIT2 &b2 00 &bh 00  MUL2          ADD2
-    ,&a2 LDR2           ,&b2 LDR2           MUL2 #80 SFT2 ADD2
-    JMP2r
+    ,&y0 STR2 ,&x0 STR2
+    #00 ,&x0 LDR #00 ,&y0 LDR MUL2      ( acc* )
+    OVR ?&overflow SWP                  ( acc* )
+    #00 ,&x1 LDR #00 ,&y0 LDR MUL2 ADD2 ( acc* )
+    #00 ,&x0 LDR #00 ,&y1 LDR MUL2 ADD2 ( acc* )
+    #00 ,&x1 LDR #00 ,&y1 LDR MUL2 #08 SFT2 ADD2 ( acc* )
+    DUP2 #7fff GTH2 ?&overflow
+    JMP2r [ &x0 $1 &x1 $1 &y0 $1 &y1 $1 ]
+    &overflow POP2 #7fff JMP2r
 
 @x16-mul-unsigned-rhs-whole ( x0_x1* y0_00* -- xy* )
-    #08 SFT2 MUL2
-    JMP2r
+    #08 SFT2 MUL2 #7fff !unsigned-min
 
 @x16-div ( x* y* -- x/y* )
     ;x16-div-unsigned !x16-signed-op
@@ -259,7 +236,7 @@
     POP2 POP2         ( [shiftk div] )
     POP2r STH2r JMP2r ( div )
 
-@x16-signed-op ( x* y* f* -- f(x,y)* )
+@x16-signed-op ( x* y* f* -> f(x,y)* )
     STH2 LIT2r 0001
     DUP2 #8000 LTH2 ?&ypos x16-negate SWPr
     &ypos SWP2 DUP2 #8000 LTH2 ?&xpos x16-negate SWPr
diff --git a/graph.tal b/graph.tal
index 3cfa926..7ec88e3 100644
--- a/graph.tal
+++ b/graph.tal
@@ -50,9 +50,18 @@
     @y1 $2                      ( upper bound of y )
 
 |0100
+    ( default settings: -4.0 to +4.0 )
+(    #fc00 DUP2 .xmin STZ2 .ymin STZ2
+    #0400 DUP2 .xmax STZ2 .ymax STZ2 )
+
+    #0800
+    DUP2 .xmax STZ2 DUP2 .ymax STZ2
+    #0000 SWP2 SUB2
+    DUP2 .xmin STZ2      .ymin STZ2
+
     ( screen size )
-    #0200 .width STZ2
-    #0200 .height STZ2
+    #0200 x-range min .width STZ2
+    #0200 y-range min .height STZ2
 
     ( colors )
     #0f0f .System/r DEO2
@@ -63,15 +72,6 @@
     .width LDZ2 .Screen/w DEO2
     .height LDZ2 .Screen/h DEO2
 
-    ( default settings: -4.0 to +4.0 )
-(    #fc00 DUP2 .xmin STZ2 .ymin STZ2
-    #0400 DUP2 .xmax STZ2 .ymax STZ2 )
-
-    #0400
-    DUP2 .xmax STZ2 DUP2 .ymax STZ2
-    #0000 SWP2 SUB2
-    DUP2 .xmin STZ2      .ymin STZ2
-
     ( TODO: we probably want separate epsilons for x and y )
     ( TODO: validate that (xmax-xmin)*eps = width exactly )
     x-range .width LDZ2 DIV2 .epsilon STZ2
@@ -89,6 +89,8 @@
     ( graph the equation )
     draw BRK
 
+@min ( x* y* -> min* ) LTH2k JMP SWP2 POP2 JMP2r
+
 @x-range ( -> x-range* ) .xmax LDZ2 .xmin LDZ2 SUB2 JMP2r
 @y-range ( -> y-range* ) .ymax LDZ2 .ymin LDZ2 SUB2 JMP2r
 
@@ -147,8 +149,8 @@
     OVR2 OVR2 evaluate ?&hit          ( x* y* [s*] )
     POP2 POP2 POP2r JMP2r             ( ; miss )
     &hit                              ( x* y* [s*] )
-    STH2kr #0001 EQU2 ?&term          ( x* y* [s*] )
-(    STH2kr .epsilon LDZ2 LTH2 ?&term          ( x* y* [s*] ) )
+(    STH2kr #0001 EQU2 ?&term          ( x* y* [s*] ) )
+    STH2kr .epsilon LDZ2 LTH2 ?&term          ( x* y* [s*] )
     LITr 01 SFT2r                     ( x* y* [h=s/2*] )
     OVR2 OVR2                         ( x* y* x* y* h* [h*] )
     STH2kr draw                       ( x* y* [h*] ; south west )