diff --git a/blk/001 b/blk/001
index f2c3353..7eb9453 100644
--- a/blk/001
+++ b/blk/001
@@ -3,6 +3,7 @@ MASTER INDEX
   3 Usage                      30 Dictionary
  70 Implementation notes      100 Block editor
 120 Linker                    140 Addressed devices
+150 Extra words
 200 Z80 assembler             260 Cross compilation
 280 Z80 boot code             350 ACIA driver
 370 SD Card driver            390 Inner core
diff --git a/blk/030 b/blk/030
index 182071e..919a99d 100644
--- a/blk/030
+++ b/blk/030
@@ -1,6 +1,7 @@
 Dictionary
 
-Be sure to read usage guide (B3) first.
+List of words defined in Inner core (B390), Core words (B420)
+and Extra words (B150).
 
 31 Glossary                    34 Symbols
 37 Entry management            40 Defining words
diff --git a/blk/037 b/blk/037
index 7b689ac..dc63872 100644
--- a/blk/037
+++ b/blk/037
@@ -1,7 +1,7 @@
 Entry management
 
-(find)   a -- a f Read at a and find it in dict. If found,
-                  f=1 and a = wordref. If not found, f=0 and
+'? x     -- a f   Find x it in dict. If found, f=1 and
+                  a = wordref. If not found, f=0 and
                   a = string addr.
 ' x      -- a     Push addr of word x to a. If not found,
                   aborts.
diff --git a/blk/102 b/blk/102
index 7d40afa..e3a81dc 100644
--- a/blk/102
+++ b/blk/102
@@ -1,3 +1,4 @@
+152 LOAD ( extras )
 103 105 LOADR
 
 : BROWSE
@@ -13,4 +14,3 @@
 ;
 
 
-
diff --git a/blk/150 b/blk/150
new file mode 100644
index 0000000..ca16a1f
--- /dev/null
+++ b/blk/150
@@ -0,0 +1,14 @@
+Extra words
+
+The Core words (B420) section contains the absolute minimum
+needed to get a usable Forth interpreter with input buffer and
+disk blocks access running. The goal here is to minimize the
+binary size of a minimum Collapse OS install.
+
+Extra words are words you will most likely want because they
+are generally useful. They are so useful that they are part
+of the Dictionary (B30).
+
+Some programs need them, so they will automatically LOAD them.
+To that end, the loader is conditional: it aborts if extra
+words are already present. Load with "152 LOAD".
diff --git a/blk/152 b/blk/152
new file mode 100644
index 0000000..e6f2bdf
--- /dev/null
+++ b/blk/152
@@ -0,0 +1,3 @@
+'? CASE NOT [IF]
+    153 157 LOADR
+[THEN] DROP ( from '? )
diff --git a/blk/427 b/blk/153
similarity index 99%
rename from blk/427
rename to blk/153
index 5e66828..30ead81 100644
--- a/blk/427
+++ b/blk/153
@@ -8,3 +8,4 @@
 ; IMMEDIATE
 : ENDOF [COMPILE] ELSE ; IMMEDIATE
 
+
diff --git a/blk/428 b/blk/154
similarity index 100%
rename from blk/428
rename to blk/154
diff --git a/blk/155 b/blk/155
new file mode 100644
index 0000000..9d380a4
--- /dev/null
+++ b/blk/155
@@ -0,0 +1,6 @@
+: FILL ( a n b -- )
+    SWAP 2 PICK + ( a b a+n ) ROT ( b a+n a ) DO ( b )
+        DUP I C!
+    LOOP
+;
+
diff --git a/blk/156 b/blk/156
new file mode 100644
index 0000000..fa80f05
--- /dev/null
+++ b/blk/156
@@ -0,0 +1,4 @@
+: EMPTY
+    LIT< _sys (find) NOT IF ABORT THEN
+    DUP HERE ! CURRENT ! ;
+
diff --git a/blk/157 b/blk/157
new file mode 100644
index 0000000..b581795
--- /dev/null
+++ b/blk/157
@@ -0,0 +1,5 @@
+: WIPE BLK( 1024 0 FILL BLK!! ;
+
+( src dst -- )
+: COPY SWAP BLK@ BLK> ! BLK! ;
+
diff --git a/blk/422 b/blk/422
index 9871af4..48d519b 100644
--- a/blk/422
+++ b/blk/422
@@ -8,9 +8,9 @@
 : LITS 34 , SCPY ;
 : LIT< WORD LITS ; IMMEDIATE
 : LITA 36 , , ;
+: '? WORD (find) ;
 : '
-    WORD (find) (?br) [ 4 , ] EXIT
+    '? (?br) [ 4 , ] EXIT
     LIT< (wnf) (find) DROP EXECUTE
 ;
 : ['] ' LITA ; IMMEDIATE
-
diff --git a/blk/434 b/blk/434
index febfb34..fb01d02 100644
--- a/blk/434
+++ b/blk/434
@@ -6,10 +6,5 @@
     LOOP
     2DROP
 ;
-: FILL ( a n b -- )
-    SWAP 2 PICK + ( a b a+n ) ROT ( b a+n a ) DO ( b )
-        DUP I C!
-    LOOP
-;
 : DELW 1- 0 SWAP C! ;
 : PREV 3 - DUP @ - ;
diff --git a/blk/435 b/blk/435
index 8a5bc52..3cb48b4 100644
--- a/blk/435
+++ b/blk/435
@@ -11,6 +11,3 @@
     WORD( HERE !  ( w )
     PREV CURRENT !
 ;
-: EMPTY
-    LIT< _sys (find) NOT IF ABORT THEN
-    DUP HERE ! CURRENT ! ;
diff --git a/blk/470 b/blk/470
index 63dcc04..29bb9b5 100644
--- a/blk/470
+++ b/blk/470
@@ -1,7 +1,2 @@
 ( b1 b2 -- )
 : LOADR 1+ SWAP DO I DUP . CRLF LOAD LOOP ;
-
-: WIPE BLK( 1024 0 FILL BLK!! ;
-
-( src dst -- )
-: COPY SWAP BLK@ BLK> ! BLK! ;
diff --git a/emul/forth.bin b/emul/forth.bin
index 2b950d3..3316bad 100644
Binary files a/emul/forth.bin and b/emul/forth.bin differ