diff --git a/common/code.fs b/common/code.fs
index f26cc00..e5e6ffd 100644
--- a/common/code.fs
+++ b/common/code.fs
@@ -16,8 +16,13 @@
 : asm r|
 
 also forth definitions
-vocabulary asm   asm definitions
-also internals
+vocabulary asm
+internals definitions
+
+: ca! ( n a -- ) dup cell-base >r cell-shift swap over lshift
+                 swap 255 swap lshift invert r@ @ and or r> ! ;
+
+also asm definitions
 
 variable code-start
 variable code-at
@@ -25,7 +30,8 @@ variable code-at
 DEFINED? posix [IF]
 also posix
 : reserve ( n -- )
-  0 swap PROT_READ PROT_WRITE PROT_EXEC or or MAP_ANONYMOUS -1 0 mmap code-start ! ;
+  0 swap PROT_READ PROT_WRITE PROT_EXEC or or
+  MAP_ANONYMOUS MAP_PRIVATE or -1 0 mmap code-start ! ;
 previous
 4096 reserve
 [THEN]
@@ -37,14 +43,19 @@ previous
 1024 reserve
 [THEN]
 
-code-start code-at !
+code-start @ code-at !
 
 : chere ( -- a ) code-at @ ;
 : callot ( n -- ) code-at +! ;
-: code, ( n -- ) chere ! cell callot ;
-: code1, ( n -- ) chere c! 1 callot ;
-: code2, ( n -- ) chere w! 2 callot ;
-: code4, ( n -- ) chere l! 4 callot ;
+: code1, ( n -- ) chere ca! 1 callot ;
+: code2, ( n -- ) dup code1, 8 rshift code1, ;
+: code3, ( n -- ) dup code2, 16 rshift code1, ;
+: code4, ( n -- ) dup code2, 16 rshift code2, ;
+cell 8 = [IF]
+: code,  dup code4, 32 rshift code4, ;
+[ELSE]
+: code,  code4, ;
+[THEN]
 : end-code   previous ;
 
 also forth definitions
diff --git a/common/utils.fs b/common/utils.fs
index 49787c1..941d3af 100644
--- a/common/utils.fs
+++ b/common/utils.fs
@@ -22,8 +22,16 @@
 
 internals definitions
 
+( Temporary for platforms without CALLCODE )
+DEFINED? CALLCODE 0= [IF]
+  create CALLCODE
+[THEN]
+
 ( Safe memory access, i.e. aligned )
-: ca@ ( a -- n ) dup cell 1- invert and @ swap cell 1- and 8 * rshift 255 and ;
+cell 1- constant cell-mask
+: cell-base ( a -- a ) cell-mask invert and ;
+: cell-shift ( a -- a ) cell-mask and 8 * ;
+: ca@ ( a -- n ) dup cell-base @ swap cell-shift rshift 255 and ;
 
 ( Print address line leaving room )
 : dump-line ( a -- a ) cr <# #s #> 20 over - >r type r> spaces ;
diff --git a/esp32/bindings.fs b/esp32/bindings.fs
index 78e51b0..ba7dcd5 100644
--- a/esp32/bindings.fs
+++ b/esp32/bindings.fs
@@ -171,16 +171,14 @@ forth definitions
 
 internals definitions
 ( Heap Capabilities )
-binary
-0001 constant MALLOC_CAP_EXEC
-0010 constant MALLOC_CAP_32BIT
-0100 constant MALLOC_CAP_8BIT
-1000 constant MALLOC_CAP_DMA
-: MALLOC_CAP_PID ( n -- ) 10000 over 11 ( 3 ) - for 2* next ;
-000010000000000 constant MALLOC_CAP_SPIRAM
-000100000000000 constant MALLOC_CAP_INTERNAL
-001000000000000 constant MALLOC_CAP_DEFAULT
-010000000000000 constant MALLOC_CAP_IRAM_8BIT
-010000000000000 constant MALLOC_CAP_RETENTION
-decimal
+1 0 lshift constant MALLOC_CAP_EXEC
+1 1 lshift constant MALLOC_CAP_32BIT
+1 2 lshift constant MALLOC_CAP_8BIT
+1 3 lshift constant MALLOC_CAP_DMA
+1 10 lshift constant MALLOC_CAP_SPIRAM
+1 11 lshift constant MALLOC_CAP_INTERNAL
+1 12 lshift constant MALLOC_CAP_DEFAULT
+1 13 lshift constant MALLOC_CAP_IRAM_8BIT
+1 14 lshift constant MALLOC_CAP_RETENTION
+1 15 lshift constant MALLOC_CAP_RTCRAM
 forth definitions
diff --git a/examples/code_xtensa.fs b/examples/code_xtensa.fs
index 5665c12..d9bbd0b 100644
--- a/examples/code_xtensa.fs
+++ b/examples/code_xtensa.fs
@@ -17,10 +17,11 @@
 asm forth 
 
 code my2*
-  $02 code1, $48 code1,             ( l32i.n  a4, a2, 0 )
-  $11 code1, $44 code1, $f0 code1,  ( slli    a4, a4, 1 )
-  $02 code1, $49 code1,             ( s32i.n  a4, a2, 0 )
-  $f0 code1, $0d code1,             ( ret.n )
+  $364100 code3, ( entry   a1, 32 )
+  $8802   code2, ( l32i.n  a8, a2, 0 )
+  $f08811 code3, ( slli    a8, a8, 1 )
+  $8902   code2, ( s32i.n  a8, a2, 0 )
+  $1df0   code2, ( retw.n )
 end-code
 
 see my2*
diff --git a/posix/posix.fs b/posix/posix.fs
index 10fe30e..86e1fe8 100644
--- a/posix/posix.fs
+++ b/posix/posix.fs
@@ -85,6 +85,7 @@ z" __errno_location" 0 sysfunc __errno_location
 1 constant PROT_READ
 2 constant PROT_WRITE
 4 constant PROT_EXEC
+$2 constant MAP_PRIVATE
 $10 constant MAP_FIXED
 $20 constant MAP_ANONYMOUS