diff --git a/doc/Emitting.markdown b/doc/Emitting.markdown
index fc757d9..543398b 100644
--- a/doc/Emitting.markdown
+++ b/doc/Emitting.markdown
@@ -266,3 +266,27 @@ temporaries are not unioned yet, but they could be.
     = .space _temp_4 2
     = .space _temp_1 1
     = .space _temp_2 2
+
+Declaring and calling an external routine.
+
+    | external chrout 65490
+    | routine main {
+    |     lda #72
+    |     jsr chrout
+    |     lda #73
+    |     jsr chrout
+    |     lda #13
+    |     jsr chrout
+    | }
+    = main:
+    =   lda #72
+    =   jsr chrout
+    =   lda #73
+    =   jsr chrout
+    =   lda #13
+    =   jsr chrout
+    =   rts
+    = 
+    = .data
+    = .alias chrout 65490
+
diff --git a/eg/demo.60p b/eg/demo.60p
index fa2906f..8c0b1a7 100644
--- a/eg/demo.60p
+++ b/eg/demo.60p
@@ -1,15 +1,15 @@
- assign byte table screen $0400
-assign byte table screen2 1274
-assign byte table screen3 1524
-assign byte table screen4 1774
+assign byte[256] screen $0400
+assign byte[256] screen2 1274
+assign byte[256] screen3 1524
+assign byte[256] screen4 1774
 
-assign byte table colormap 55296
-assign byte table colormap2 55546
-assign byte table colormap3 55796
-assign byte table colormap4 56046
+assign byte[256] colormap 55296
+assign byte[256] colormap2 55546
+assign byte[256] colormap3 55796
+assign byte[256] colormap4 56046
 
 assign byte vic_border 53280
-assign byte table vic_bg 53281
+assign byte[4] vic_bg 53281
 
 assign vector cinv 788
 reserve vector save_cinv
diff --git a/eg/game.60p b/eg/game.60p
index f729ec7..dbd0175 100644
--- a/eg/game.60p
+++ b/eg/game.60p
@@ -1,15 +1,15 @@
-assign byte table screen $0400
-assign byte table screen2 1274
-assign byte table screen3 1524
-assign byte table screen4 1774
+assign byte[256] screen $0400
+assign byte[256] screen2 1274
+assign byte[256] screen3 1524
+assign byte[256] screen4 1774
 
-assign byte table colormap 55296
-assign byte table colormap2 55546
-assign byte table colormap3 55796
-assign byte table colormap4 56046
+assign byte[256] colormap 55296
+assign byte[256] colormap2 55546
+assign byte[256] colormap3 55796
+assign byte[256] colormap4 56046
 
 assign byte vic_border 53280
-assign byte table vic_bg 53281
+assign byte[4] vic_bg 53281
 
 assign byte joy2 $dc00
 
diff --git a/eg/hello-world.60p b/eg/hello-world.60p
new file mode 100644
index 0000000..7e4cadc
--- /dev/null
+++ b/eg/hello-world.60p
@@ -0,0 +1,13 @@
+reserve byte[13] message: "HELLO, WORLD!"
+external chrout 65490
+routine main {
+    ldy #0
+    repeat bne {
+        lda message, y
+        jsr chrout
+        iny
+        cpy #13
+    }
+    lda #13
+    jsr chrout
+}
diff --git a/eg/hi.60p b/eg/hi.60p
deleted file mode 100644
index 6071538..0000000
--- a/eg/hi.60p
+++ /dev/null
@@ -1,9 +0,0 @@
-external chrout 65490
-routine main {
-    lda #72
-    jsr chrout
-    lda #73
-    jsr chrout
-    lda #13
-    jsr chrout
-}
diff --git a/eg/screen3.60p b/eg/screen3.60p
index 99c83fb..789a27a 100644
--- a/eg/screen3.60p
+++ b/eg/screen3.60p
@@ -1,4 +1,4 @@
-assign byte table screen 1024
+assign byte[256] screen 1024
 reserve byte value
 routine main {
     lda #0
diff --git a/src/SixtyPical/Analyzer.hs b/src/SixtyPical/Analyzer.hs
index bb8870b..fcebe7b 100644
--- a/src/SixtyPical/Analyzer.hs
+++ b/src/SixtyPical/Analyzer.hs
@@ -53,14 +53,19 @@ analyzeProgram program@(Program decls routines) =
           updateRoutCtx nm dst (UpdatedWith src) routCtx
 
       checkInstr nm (JSR name) progCtx routCtx =
-          let
-              Just calledRout = lookupRoutine program name
-          in
-              case Map.lookup name progCtx of
-                  Just calledRoutCtx ->
-                      mergeRoutCtxs nm routCtx calledRoutCtx calledRout
-                  Nothing ->
-                      error ("can't call routine '" ++ name ++ "' before it is defined")
+          case lookupRoutine program name of
+              Just calledRout ->
+                  case Map.lookup name progCtx of
+                      Just calledRoutCtx ->
+                          mergeRoutCtxs nm routCtx calledRoutCtx calledRout
+                      Nothing ->
+                          error ("can't call routine '" ++ name ++ "' before it is defined")
+              Nothing ->
+                  -- it must be an external.
+                  -- TODO: merge in any poisoning/outputs that are declared
+                  -- on the external.  for now,
+                  routCtx
+
       checkInstr nm (CMP reg addr) progCtx routCtx =
           -- TODO: mark Carry bit as "touched" here
           routCtx
diff --git a/src/SixtyPical/Checker.hs b/src/SixtyPical/Checker.hs
index 6dc6aee..4609f5f 100644
--- a/src/SixtyPical/Checker.hs
+++ b/src/SixtyPical/Checker.hs
@@ -69,7 +69,7 @@ consistentInitialTableSizes p@(Program decls routines) =
 checkAndTransformProgram :: Program -> Maybe Program
 checkAndTransformProgram program =
     if
-        trueOrDie "missing 'main' routine" (routineDeclared "main" program) &&
+        trueOrDie ("missing 'main' routine: " ++ show program) (routineDeclared "main" program) &&
         trueOrDie "duplicate location name" (noDuplicateDecls program) &&
         trueOrDie "duplicate routine name" (noDuplicateRoutines program) &&
         trueOrDie "undeclared routine" (noUseOfUndeclaredRoutines program) &&
diff --git a/src/SixtyPical/Model.hs b/src/SixtyPical/Model.hs
index 27ee79e..933aa97 100644
--- a/src/SixtyPical/Model.hs
+++ b/src/SixtyPical/Model.hs
@@ -111,6 +111,7 @@ isLocationDecl _ = False
 isInitializedDecl (Assign _ _ _) = False
 isInitializedDecl (Reserve _ _ (v:vs)) = True
 isInitializedDecl (Reserve _ _ []) = False
+isInitializedDecl _ = False
 
 declaredLocationNames (Program decls _) =
     map (getDeclLocationName) (filter (isLocationDecl) decls)