diff --git a/mandel.s b/mandel.s
index 8bd1a27..6be37d2 100644
--- a/mandel.s
+++ b/mandel.s
@@ -296,6 +296,7 @@ viewport_zoom:
     .byte 7
     .byte 5
     .byte 7
+    .byte 7
 
 viewport_ox:
     .dword ($00000000 & $3fffffff) << 2
@@ -303,6 +304,7 @@ viewport_ox:
     .dword ($ff110000 & $3fffffff) << 2
     .dword ($fe400000 & $3fffffff) << 2
     .dword ($fe3b0000 & $3fffffff) << 2
+    .dword $fd220000
 
 viewport_oy:
     .dword ($00000000 & $3fffffff) << 2
@@ -310,6 +312,7 @@ viewport_oy:
     .dword ($ffbe0000 & $3fffffff) << 2
     .dword ($00000000 & $3fffffff) << 2
     .dword ($fffe0000 & $3fffffff) << 2
+    .dword $ff000000
 
 ; 2 + 9 * byte cycles
 .macro add bytes, dest, arg1, arg2
@@ -1426,6 +1429,8 @@ number_keys:
     beq four
     cpy #KEY_5
     beq five
+    cpy #KEY_6
+    beq six
     jmp skip_char
 
 one:
@@ -1442,6 +1447,9 @@ four:
     jmp load_key_viewport
 five:
     ldx #4
+    jmp load_key_viewport
+six:
+    ldx #5
     ; fall through
 load_key_viewport:
     jsr load_viewport
diff --git a/readme.md b/readme.md
index 881890a..2c9efc1 100644
--- a/readme.md
+++ b/readme.md
@@ -18,7 +18,7 @@ Enjoy! I'll probably work on this off and on for the next few weeks until I've g
 
 ## Current state
 
-Basic rendering is functional, with interactive zoom/pan (+/-/arrows) and 5 preset viewports via the number keys.
+Basic rendering is functional, with interactive zoom/pan (+/-/arrows) and 6 preset viewports via the number keys.
 
 The 16-bit signed integer multiplication takes two 16-bit inputs and emits one 32-bit output in the zero page, using the Atari OS ROM's floating point registers as workspaces. Inputs are clobbered.