Downsized memory

src/hence/emulator.cr

@@ -79,7 +79,7 @@ module Hence
         @reg_inp = 0_u16,
         @reg_out = 0_u16,
         @stack = Slice(UInt16).new({{ 8 * 1024 }}),
-        @memory = Slice(UInt16).new({{ 24 * 1024 }})
+        @memory = Slice(UInt16).new({{ 16 * 1024 }})
       )
       end
 
@@ -226,8 +226,10 @@ module Hence
           @program[address].to_u16
         elsif address < {{ 40 * 1024 }}
           @stack[address - {{ 32 * 1024 }}]
-        else
+        elsif address < {{ 56 * 1024 }}
           @memory[address - {{ 40 * 1024 }}]
+        else
+          0_u16
         end
       end
 
@@ -238,8 +240,10 @@ module Hence
           @stack[address - {{ 32 * 1024 }}] = value
 
           value
-        else
+        elsif address < {{ 56 * 1024 }}
           @memory[address - {{ 40 * 1024 }}] = value
+        else
+          0_u16
         end
       end
     end