hacking method not found

was using exit, since raise is not implemented. This was ambiguous as all programs exit.
Using :died as special kernel code and bending it, and reporting it in interpreter.

lib/arm/translator.rb

@@ -139,10 +139,12 @@ module Arm
     end
 
     def translate_Syscall( code )
-      call_codes = { :putstring => 4 , :exit => 1    }
-      int_code = call_codes[code.name]
-      raise "Not implemented syscall, #{code.name}" unless int_code
-      send( code.name , int_code )
+      call_codes = { putstring: 4 , exit: 1 }
+      name = code.name
+      name = :exit if name == :died
+      int_code = call_codes[name]
+      raise "Not implemented syscall, #{name}" unless int_code
+      send( name , int_code )
     end
 
     def putstring( int_code )

lib/mom/instruction/resolve_method.rb

@@ -65,7 +65,7 @@ module Mom
         # temporary, need to raise really.
         factory! << Parfait.object_space.get_factory_for(:Integer)
         integer_tmp! << factory[:reserve]
-        Mom::Builtin.emit_syscall( builder , :exit ) #uses integer_tmp
+        Mom::Builtin.emit_syscall( builder , :died ) #uses integer_tmp
 
         add_code ok_label
         cache_entry[:cached_method] << callable_method

lib/risc/interpreter.rb

@@ -245,6 +245,8 @@ module Risc
       when :exit
         set_instruction(nil)
         return false
+      when :died
+        raise "Method not found #{@registers[:r0]}"
       else
         raise "un-implemented syscall #{name}"
       end