Interesting dead end we've got ourselves into here.

eg/intr1.60p

@@ -0,0 +1,23 @@
+byte vic_border @ 53280
+
+vector cinv @ 788
+vector save_cinv
+
+routine our_cinv
+  inputs vic_border
+  outputs vic_border
+  trashes z, n
+{
+    inc vic_border
+}
+
+routine main
+  inputs cinv, our_cinv
+  outputs cinv, save_cinv
+  trashes a, n, z
+{
+    with interrupts off {
+        copy cinv, save_cinv
+        copy our_cinv, cinv
+    }
+}

src/sixtypical/compiler.py

@@ -3,7 +3,7 @@
 from sixtypical.ast import Program, Routine, Block, Instr
 from sixtypical.model import (
     ConstantRef, LocationRef,
-    TYPE_BIT,
+    TYPE_BIT, TYPE_ROUTINE, TYPE_VECTOR,
     REG_A, REG_X, REG_Y, FLAG_Z, FLAG_N, FLAG_V, FLAG_C
 )
 from sixtypical.emitter import Label, Byte
@@ -241,5 +241,13 @@ class Compiler(object):
             self.emitter.emit(SEI())
             self.compile_block(instr.block)
             self.emitter.emit(CLI())
+        elif opcode == 'copy':
+            if src.type in (TYPE_ROUTINE, TYPE_VECTOR) and dest.type == TYPE_VECTOR:
+                self.emitter.emit(LDA(Absolute(self.labels[src.name])))
+                self.emitter.emit(STA(Absolute(self.labels[dest.name])))
+                self.emitter.emit(LDA(Absolute(self.labels[src.name].clone(offset=1))))
+                self.emitter.emit(STA(Absolute(self.labels[dest.name].clone(offset=1))))
             else:
-            raise NotImplementedError
+                raise NotImplementedError(src.type)
+        else:
+            raise NotImplementedError(opcode)