diff --git a/asm/forth-dictionary.s b/asm/forth-dictionary.s
index b4e9c2d..e8f7bb1 100644
--- a/asm/forth-dictionary.s
+++ b/asm/forth-dictionary.s
@@ -4135,13 +4135,12 @@ cont:     sta   [WR]
           sta   [WR],y
           lda   WR
           clc
-          adc   #.loword(3)
+          adc   #$0003            ; skip 3 more since we are dealing with words
           sta   WR
-          lda   WR+2
-          adc   #.hiword(3)
-          sta   WR+2
+          bcc   :+
+          inc   WR+2
           clc
-          rtl
+:         rtl
 eword
 
 ; H: ( addr len -- ) Perform LWFLIP on the cells in memory.
@@ -4708,8 +4707,9 @@ done:     tya
           adc   XR+2
           tay
           lda   WR+2
-          adc   #$0000
-          jsr   _pushay
+          bcc   :+
+          inc   a                   ; handle carry
+:         jsr   _pushay
           lda   XR                  ; len of str 2 = XR-(XR+2)
           sec
           sbc   XR+2
@@ -4899,11 +4899,12 @@ dword     rBODY,">BODY"
           jmp   _throway
 :         lda   WR
           clc
-          adc   #$05
+          adc   #$0005
           tay
           lda   WR+2
-          adc   #$00
-          PUSHNEXT
+          bcc   :+
+          inc   a
+:         PUSHNEXT
 eword
 
 ; H: ( a-addr -- xt ) return xt of word with body at a-addr, if unable throw exc. -31
@@ -7057,7 +7058,9 @@ lp:       ONLIT 0                 ; clear #LINE since we are at input prompt
 eword
 __doquit  = QUIT::code
 
-PLATFORM_INCLUDE "platform-words.s" ; Platform additional dictionary words
+.if .strlen(PLATFORM) > 0
+  .include "platform-words.s" ; Platform additional dictionary words
+.endif
 
 ; Leave these toward the top
 
diff --git a/asm/interpreter.s b/asm/interpreter.s
index 6fc3520..cca4f35 100644
--- a/asm/interpreter.s
+++ b/asm/interpreter.s
@@ -56,31 +56,68 @@
 .endif
 
 .proc     _next
-          inc   IP                ; inline fetch
-          bne   :+
-          inc   IP+2
-:         lda   [IP]              ; low word
-          tay
-          inc   IP
-          bne   :+
-          inc   IP+2
-:         inc   IP
-          bne   :+
-          inc   IP+2
-:         lda   [IP]              ; high word
-          inc   IP
-          bne   :+
+.if 1
+          ldy   #$0003            ; (3)/3
+          lda   [IP],y            ; (7)/2
+.if !no_fast_lits
+          bne   :++
+          jsr   _stackdecr
+          sta   STACKBASE+2,x
+          dey
+          dey
+          lda   [IP],y
+          sta   STACKBASE+0,x
+          lda   IP
+          clc
+          adc   #$0004
+          sta   IP
+          bcc  :+
           inc   IP+2
+:         bra   _next
+:
+.endif
+          xba                     ; (3)/1 xxHH -> HHxx
+          pha                     ; (4)/1 stack ...HHxx
+          phb                     ; (3)/1 stack ...HHxxxx
+          dey                     ; (2)/1
+          dey                     ; (2)/1
+          lda   [IP],y            ; (7)/2 MMLL
+          sta   1,s               ; (5)/2 stack ...HHMMLL
+          lda   IP                ; (4)/2
+          clc                     ; (2)/1
+          adc   #$0004            ; (3)/2
+          sta   IP                ; (4)/2
+          bcc  :+                 ; (2)/2
+          inc   IP+2              ; (6)/2
+:         rtl                     ; (6)/1 (63)/26         
+.else
+; old implementation
+          inc   IP                ; (6)/2 inline fetch
+          bne   :+                ; (2)/2
+          inc   IP+2              ; (6)/2
+:         lda   [IP]              ; (7)/2 low word
+          tay                     ; (2)/1
+          inc   IP                ; (6)/2
+          bne   :+                ; (2)/2
+          inc   IP+2              ; (6)/2
+:         inc   IP                ; (6)/2
+          bne   :+                ; (2)/2
+          inc   IP+2              ; (6)/2
+:         lda   [IP]              ; (7)/2 high word
+          inc   IP                ; (6)/2
+          bne   :+                ; (2)/2
+          inc   IP+2              ; (6)/2 = (72)/29+run=(82)
 :         
 .if !no_fast_lits
           ora   #$0000            ; faster than php+plp
           beq   fast_num
 .endif
-run:      sep   #SHORT_A
-          pha
-          rep   #SHORT_A
-          phy
-          rtl
+.endif
+run:      sep   #SHORT_A          ; (3)/1
+          pha                     ; (4)/1
+          rep   #SHORT_A          ; (3)/1
+          phy                     ; (4)/1
+          rtl                     ; (6)/1 = 20/5          
 fast_num: jsr   _pushay
           bra   _next
 .endproc
diff --git a/asm/memmgr.s b/asm/memmgr.s
index f4316a5..6f1927f 100644
--- a/asm/memmgr.s
+++ b/asm/memmgr.s
@@ -15,10 +15,10 @@
 ; Tunables
 SPLIT_THRESH = 8                  ; if block can be split and remainder have this many
                                   ; bytes + 6 bytes header, split it
-MIN_BRK     = $400                ; minimum break between DHERE and HIMEM in pages
+MIN_BRK     = $400                ; minimum break between DHERE and HIMEM in pages, 16 bit only
 
 ; Constants
-HDR_SIZE    = 6
+HDR_SIZE    = 6                   ; 16 bits only
 
 ; Allocate XR bytes, return carry set+pointer in AY if successful
 ; or carry clear+AY=0 if unsuccessful
@@ -54,9 +54,9 @@ grow:     jsr   _grow_heap
           adc   #.loword(HDR_SIZE)
           tay
           lda   WR+2
-          clc
-          adc   #.hiword(HDR_SIZE)
-          sec
+          bcc   :+
+          inc   a
+:         sec
           rts
 .endproc
 
@@ -86,10 +86,9 @@ grow:     jsr   _grow_heap
           clc
           adc   #.loword(HDR_SIZE)
           sta   YR
-          lda   YR+2
-          adc   #.hiword(HDR_SIZE)
-          sta   YR+2              ; ok now YR points to child block
-          ldy   #$04              ; first mark child block free
+          bcc   :+
+          inc   YR+2              ; ok now YR points to child block
+:         ldy   #$04              ; first mark child block free
           lda   #$0000            ; by zeroing its flags
           sta   [YR],y
           dey                     
@@ -284,16 +283,16 @@ none:     pla                     ; drop the block pointer
           sec
           sbc   #.loword(HDR_SIZE)
           sta   YR
-          lda   YR+2
-          sbc   #.hiword(HDR_SIZE)
-          sta   YR+2
-          lda   DHERE           ; now compare to DHERE+minimum break
+          bcs   :+
+          dec   YR+2
+:         lda   DHERE           ; now compare to DHERE+minimum break
           clc
           adc   #.loword(MIN_BRK)
           tay
           lda   DHERE+2
-          adc   #.hiword(MIN_BRK)
-          cmp   YR+2
+          bcc   :+
+          inc   a
+:         cmp   YR+2
           bne   :+
           tya
           cmp   YR