diff --git a/templates/wasm/output_sound.wat b/templates/wasm/output_sound.wat
index 028e13a..83b651a 100644
--- a/templates/wasm/output_sound.wat
+++ b/templates/wasm/output_sound.wat
@@ -1,5 +1,5 @@
 {{- if not .Output16Bit }}
-            (i64.store (global.get $outputBufPtr) (i64.load (i32.const 4128))) ;; load the sample from left & right channels as one 64bit int and store it in the address pointed by outputBufPtr
+            (i64.store (global.get $outputBufPtr) (i64.load (i32.const {{index .Labels "su_globalports"}}))) ;; load the sample from left & right channels as one 64bit int and store it in the address pointed by outputBufPtr
             (global.set $outputBufPtr (i32.add (global.get $outputBufPtr) (i32.const 8)))      ;; advance outputbufptr
 {{- else }}
             (local.set $channel (i32.const 0))
@@ -7,7 +7,7 @@
                 (i32.store16 (global.get $outputBufPtr) (i32.trunc_f32_s
                     (f32.mul
                         (call $clip
-                            (f32.load offset=4128 (i32.mul (local.get $channel) (i32.const 4)))
+                            (f32.load offset={{index .Labels "su_globalports"}} (i32.mul (local.get $channel) (i32.const 4)))
                         )
                         (f32.const 32767)
                     )
@@ -16,4 +16,4 @@
                 (br_if $channelLoop (local.tee $channel (i32.eqz (local.get $channel))))
             end
 {{- end }}
-            (i64.store (i32.const 4128) (i64.const 0)) ;; clear the left and right ports
\ No newline at end of file
+            (i64.store (i32.const {{index .Labels "su_globalports"}}) (i64.const 0)) ;; clear the left and right ports
\ No newline at end of file
diff --git a/templates/wasm/patch.wat b/templates/wasm/patch.wat
index ffc82d1..44b3fff 100644
--- a/templates/wasm/patch.wat
+++ b/templates/wasm/patch.wat
@@ -13,7 +13,7 @@
                 {{- $addr := sub (index .Labels "su_vm_transformcounts") 1}}
                 (if (i32.lt_u (local.get $paramNum) (i32.load8_u offset={{$addr}} (local.get $opcode)))(then ;;(i32.ge (local.get $paramNum) (i32.load8_u (local.get $opcode)))  /*TODO: offset to transformvalues
                     (local.set $WRKplusparam (i32.add (global.get $WRK) (local.get $paramX4)))
-                    (f32.store offset=512
+                    (f32.store offset={{index .Labels "su_transformedvalues"}}
                         (local.get $paramX4)
                         (f32.add
                             (f32.mul
@@ -59,7 +59,7 @@
 ;; The transformed values start at 512 (TODO: change magic constants somehow)
 ;;-------------------------------------------------------------------------------
 (func $input (param $inputNumber i32) (result f32)
-    (f32.load offset=512 (i32.mul (local.get $inputNumber) (i32.const 4)))
+    (f32.load offset={{index .Labels "su_transformedvalues"}} (i32.mul (local.get $inputNumber) (i32.const 4)))
 )
 
 ;;-------------------------------------------------------------------------------
diff --git a/templates/wasm/player.wat b/templates/wasm/player.wat
index 2fa2f36..42d538c 100644
--- a/templates/wasm/player.wat
+++ b/templates/wasm/player.wat
@@ -5,7 +5,7 @@
 ;    Patterns
 ;-------------------------------------------------------------------------------
 */}}
-{{- .SetLabel "su_patterns"}}
+{{- .SetDataLabel "su_patterns"}}
 {{- $m := .}}
 {{- range .Patterns}}
     {{- range .}}
@@ -18,7 +18,7 @@
 ;    Tracks
 ;-------------------------------------------------------------------------------
 */}}
-{{- .SetLabel "su_tracks"}}
+{{- .SetDataLabel "su_tracks"}}
 {{- $m := .}}
 {{- range .Sequences}}
     {{- range .}}
@@ -31,7 +31,7 @@
 ;    The code for this patch, basically indices to vm jump table
 ;-------------------------------------------------------------------------------
 */}}
-{{- .SetLabel "su_patch_code"}}
+{{- .SetDataLabel "su_patch_code"}}
 {{- range .Commands}}
 {{- $.DataB .}}
 {{- end}}
@@ -41,7 +41,7 @@
 ;    The parameters / inputs to each opcode
 ;-------------------------------------------------------------------------------
 */}}
-{{- .SetLabel "su_patch_parameters"}}
+{{- .SetDataLabel "su_patch_parameters"}}
 {{- range .Values}}
 {{- $.DataB .}}
 {{- end}}
@@ -51,7 +51,7 @@
 ;    Delay times
 ;-------------------------------------------------------------------------------
 */}}
-{{- .SetLabel "su_delay_times"}}
+{{- .SetDataLabel "su_delay_times"}}
 {{- range .DelayTimes}}
 {{- $.DataW .}}
 {{- end}}
@@ -61,11 +61,61 @@
 ; The number of transformed parameters each opcode takes
 ;-------------------------------------------------------------------------------
 */}}
-{{- .SetLabel "su_vm_transformcounts"}}
+{{- .SetDataLabel "su_vm_transformcounts"}}
 {{- range .Instructions}}
 {{- $.TransformCount . | $.ToByte | $.DataB}}
 {{- end}}
 
+{{- /*
+;-------------------------------------------------------------------------------
+; Allocate memory for stack.
+; Stack of 64 float signals is enough for everybody... right?
+; Note: as the stack grows _downwards_ the label is _after_ stack
+;-------------------------------------------------------------------------------
+*/}}
+{{- .Align}}
+{{- .Block 256}}
+{{- .SetBlockLabel "su_stack"}}
+
+{{- /*
+;-------------------------------------------------------------------------------
+; Allocate memory for transformed values.
+;-------------------------------------------------------------------------------
+*/}}
+{{- .Align}}
+{{- .SetBlockLabel "su_transformedvalues"}}
+{{- .Block 32}}
+
+{{- /*
+;-------------------------------------------------------------------------------
+; Uninitialized memory for synth, delaylines & outputbuffer
+;-------------------------------------------------------------------------------
+*/}}
+{{- .Align}}
+{{- if ne .VoiceTrackBitmask 0}}
+{{- .SetBlockLabel "su_trackcurrentvoice"}}
+{{- .Block 32}}
+{{- end}}
+{{- .Align}}
+{{- .SetBlockLabel "su_synth"}}
+{{- .Block 32}}
+{{- .SetBlockLabel "su_globalports"}}
+{{- .Block 32}}
+{{- .SetBlockLabel "su_voices"}}
+{{- .Block 131072}}
+{{- .Align}}
+{{- .SetBlockLabel "su_delaylines"}}
+{{- .Block (int (mul 262156 .Song.Patch.NumDelayLines))}}
+{{- .Align}}
+{{- .SetBlockLabel "su_outputbuffer"}}
+{{- if .Output16Bit}}
+{{- .Block (int (mul .PatternLength .SequenceLength .Song.SamplesPerRow 4))}}
+{{- else}}
+{{- .Block (int (mul .PatternLength .SequenceLength .Song.SamplesPerRow 8))}}
+{{- end}}
+{{- .SetBlockLabel "su_outputend"}}
+
+
 ;;------------------------------------------------------------------------------
 ;; Import the difficult math functions from javascript
 ;; (seriously now, it's 2020)
@@ -82,9 +132,8 @@
 
 ;;------------------------------------------------------------------------------
 ;; The one and only memory
-;; TODO: Its size should be calculated just to fit, but not more
 ;;------------------------------------------------------------------------------
-(memory (export "m") 256)
+(memory (export "m") {{.MemoryPages}})
 
 ;;------------------------------------------------------------------------------
 ;; Globals. Putting all with same initialization value should compress most
@@ -106,11 +155,11 @@
 (global $voice (mut i32) (i32.const 0))
 (global $voicesRemain (mut i32) (i32.const 0))
 (global $randseed (mut i32) (i32.const 1))
-(global $sp (mut i32) (i32.const 2048))
-(global $outputBufPtr (mut i32) (i32.const 8388608))
+(global $sp (mut i32) (i32.const {{index .Labels "su_stack"}}))
+(global $outputBufPtr (mut i32) (i32.const {{index .Labels "su_outputbuffer"}}))
 ;; TODO: only export start and length with certain compiler options; in demo use, they can be hard coded
 ;; in the intro
-(global $outputStart (export "s") i32 (i32.const 8388608)) ;; TODO: do not hard code, layout memory somehow intelligently
+(global $outputStart (export "s") i32 (i32.const {{index .Labels "su_outputbuffer"}}))
 (global $outputLength (export "l") i32 (i32.const {{if .Output16Bit}}{{mul .PatternLength .SequenceLength .Song.SamplesPerRow 4}}{{else}}{{mul .PatternLength .SequenceLength .Song.SamplesPerRow 8}}{{end}}))
 (global $output16bit (export "t") i32 (i32.const {{if .Output16Bit}}1{{else}}0{{end}}))
 
@@ -168,13 +217,11 @@
                 (global.set $COM_instr_start (global.get $COM))
                 (global.set $VAL_instr_start (global.get $VAL))
 {{- end}}
-                (global.set $WRK (i32.const 4160))
-                (global.set $voice (i32.const 4160))
+                (global.set $WRK (i32.const {{index .Labels "su_voices"}}))
+                (global.set $voice (i32.const {{index .Labels "su_voices"}}))
                 (global.set $voicesRemain (i32.const {{.Song.Patch.NumVoices | printf "%v"}}))
 {{- if .HasOp "delay"}}
-                (global.set $delayWRK (i32.const 262144)) ;; BAD IDEA: we are limited to something like 30 delay lines
-                ;; after that, the delay lines start to overwrite the outputbuffer. Find a way to layout the memory
-                ;; based on the song, instead of hard coding addressed.
+                (global.set $delayWRK (i32.const {{index .Labels "su_delaylines"}}))
 {{- end}}
                 (call $su_run_vm)
                 {{- template "output_sound.wat" .}}
@@ -217,10 +264,10 @@
         (i32.load8_u offset={{index .Labels "su_patterns"}})
         (local.tee $note)
         (if (i32.ne (i32.const {{.Hold}}))(then
-            (i32.store offset=4164
+            (i32.store offset={{add (index .Labels "su_voices") 4}}
                 (i32.mul
                     (i32.add
-                        (local.tee $voiceNo (i32.load8_u offset=768 (local.get $tracksRemaining)))
+                        (local.tee $voiceNo (i32.load8_u offset={{index .Labels "su_trackcurrentvoice"}} (local.get $tracksRemaining)))
                         (local.get $firstVoice)
                     )
                     (i32.const 4096)
@@ -239,11 +286,11 @@
                         )
                         (i32.const 4096)
                     )
-                    (i32.const 4160)
+                    (i32.const {{index .Labels "su_voices"}})
                 ))
                 (memory.fill (local.get $di) (i32.const 0) (i32.const 4096))
                 (i32.store (local.get $di) (local.get $note))
-                (i32.store8 offset=768 (local.get $tracksRemaining) (local.get $voiceNo))
+                (i32.store8 offset={{index .Labels "su_trackcurrentvoice"}} (local.get $tracksRemaining) (local.get $voiceNo))
             ))
         ))
         (local.set $si (i32.add (local.get $si) (i32.const {{.SequenceLength}})))
@@ -256,7 +303,7 @@
 (func $su_update_voices (local $si i32) (local $di i32) (local $tracksRemaining i32) (local $note i32)
     (local.set $tracksRemaining (i32.const {{len .Sequences}}))
     (local.set $si (global.get $pattern))
-    (local.set $di (i32.const 4160))
+    (local.set $di (i32.const {{index .Labels "su_voices"}}))
     loop $track_loop
         (i32.load8_u offset={{index .Labels "su_tracks"}} (local.get $si))
         (i32.mul (i32.const {{.PatternLength}}))
diff --git a/templates/wasm/sinks.wat b/templates/wasm/sinks.wat
index 7d3a83d..3e3c53a 100644
--- a/templates/wasm/sinks.wat
+++ b/templates/wasm/sinks.wat
@@ -6,7 +6,7 @@
 ;;   Stereo: also add outgain*ST1 to main right port and auxgain*ST1 to aux1 right
 ;;-------------------------------------------------------------------------------
 (func $su_op_outaux (param $stereo i32) (local $addr i32)
-    (local.set $addr (i32.const 4128))
+    (local.set $addr (i32.const {{index .Labels "su_globalports"}}))
 {{- if .Stereo "outaux"}}
     loop $stereoLoop
 {{- end}}
@@ -47,7 +47,7 @@
 ;;   Stereo: also add gain*ST1 to right port
 ;;-------------------------------------------------------------------------------
 (func $su_op_aux (param $stereo i32) (local $addr i32)
-    (local.set $addr (i32.add (i32.mul (call $scanValueByte) (i32.const 4)) (i32.const 4128)))
+    (local.set $addr (i32.add (i32.mul (call $scanValueByte) (i32.const 4)) (i32.const {{index .Labels "su_globalports"}})))
 {{- if .Stereo "aux"}}
     loop $stereoLoop
 {{- end}}
@@ -97,7 +97,7 @@
     (local.set $scaledAddress (i32.add (i32.mul (i32.and (local.get $address) (i32.const 0x7FF7)) (i32.const 4))
 {{- if .SupportsGlobalSend}}
         (select
-            (i32.const 4096)
+            (i32.const {{index .Labels "su_synth"}})
 {{- end}}
             (global.get $voice)
 {{- if .SupportsGlobalSend}}
@@ -137,7 +137,7 @@
 {{- end}}
 ;;-------------------------------------------------------------------------------
 (func $su_op_out (param $stereo i32) (local $ptr i32)
-    (local.set $ptr (i32.const 4128)) ;; synth.left, but should not be magic constant
+    (local.set $ptr (i32.const {{index .Labels "su_globalports"}})) ;; synth.left
     (f32.store (local.get $ptr)
         (f32.add
             (f32.mul
@@ -147,7 +147,7 @@
             (f32.load (local.get $ptr))
         )
     )
-    (local.set $ptr (i32.const 4132)) ;; synth.right, but should not be magic constant
+    (local.set $ptr (i32.const {{add (index .Labels "su_globalports") 4}})) ;; synth.right, note that ATM does not seem to support mono ocpode at all
     (f32.store (local.get $ptr)
         (f32.add
             (f32.mul
diff --git a/templates/wasm/sources.wat b/templates/wasm/sources.wat
index cec12c6..d83edb7 100644
--- a/templates/wasm/sources.wat
+++ b/templates/wasm/sources.wat
@@ -183,7 +183,7 @@
 {{- if .SupportsParamValueOtherThan "oscillator" "unison" 0}}
     (call $push (f32.add (call $pop) (call $pop)))
     (if (local.tee $unison (i32.sub (local.get $unison) (i32.const 1)))(then
-        (f32.store offset={{.InputNumber "oscillator" "phase" | mul 4 | add 512}} (i32.const 0)
+        (f32.store offset={{.InputNumber "oscillator" "phase" | mul 4 | add (index .Labels "su_transformedvalues")}} (i32.const 0)
             (f32.add
                 (call $input (i32.const {{.InputNumber "oscillator" "phase"}}))
                 (f32.const 0.08333333) ;; 1/12, add small phase shift so all oscillators don't start in phase
@@ -328,7 +328,7 @@
 {{- if .Stereo "in"}}
     (i32.add (local.get $stereo)) ;; start from right channel if stereo
 {{- end}}
-    (local.set $addr (i32.add (i32.mul (i32.const 4)) (i32.const 4128)))
+    (local.set $addr (i32.add (i32.mul (i32.const 4)) (i32.const {{index .Labels "su_globalports"}})))
 {{- if .Stereo "in"}}
     loop $stereoLoop
 {{- end}}
diff --git a/vm/compiler/wasm_macros.go b/vm/compiler/wasm_macros.go
index 92db1e5..f7341c9 100644
--- a/vm/compiler/wasm_macros.go
+++ b/vm/compiler/wasm_macros.go
@@ -5,39 +5,70 @@ import (
 	"encoding/binary"
 )
 
+// WasmMacros are the macros called from .wat templates
+//
+// NOTE! Due to the single pass nature of the compilation and the way memory is
+// organized, you should initialize all initialized data in the .wat files using
+// DataB, DataW and DataD macros _before_ any calls to Block. Block allocates
+// uninitialized data blocks from the memory.
 type WasmMacros struct {
-	data   *bytes.Buffer
-	Labels map[string]int
+	data       *bytes.Buffer
+	blockStart int
+	blockAlign int
+	Labels     map[string]int
 }
 
 func NewWasmMacros() *WasmMacros {
 	return &WasmMacros{
-		data:   new(bytes.Buffer),
-		Labels: map[string]int{},
+		data:       new(bytes.Buffer),
+		blockAlign: 128,
+		Labels:     map[string]int{},
 	}
 }
 
-func (wm *WasmMacros) SetLabel(label string) string {
+func (wm *WasmMacros) SetDataLabel(label string) string {
 	wm.Labels[label] = wm.data.Len()
 	return ""
 }
 
+func (wm *WasmMacros) SetBlockLabel(label string) string {
+	wm.Labels[label] = wm.blockStart
+	return ""
+}
+
+func (wm *WasmMacros) Align() string {
+	wm.blockStart += wm.blockAlign - 1 - ((wm.blockStart + wm.blockAlign - 1) % wm.blockAlign)
+	return ""
+}
+
+func (wm *WasmMacros) MemoryPages() int {
+	return (wm.blockStart + 65535) / 65536
+}
+
 func (wm *WasmMacros) GetLabel(label string) int {
 	return wm.Labels[label]
 }
 
 func (wm *WasmMacros) DataB(value byte) string {
 	binary.Write(wm.data, binary.LittleEndian, value)
+	wm.blockStart++
 	return ""
 }
 
 func (wm *WasmMacros) DataW(value uint16) string {
 	binary.Write(wm.data, binary.LittleEndian, value)
+	wm.blockStart += 2
 	return ""
 }
 
 func (wm *WasmMacros) DataD(value uint32) string {
 	binary.Write(wm.data, binary.LittleEndian, value)
+	wm.blockStart += 4
+	return ""
+}
+
+func (wm *WasmMacros) Block(value int) string {
+	wm.blockStart += value
 	return ""
 }