finally creating less objects in the test

basic still #23 , now applied
Basic size of 20, interpreter gets 50 and the full set is 1024

Tests run more than twice as fast!!

test/risc/test_interpreter.rb

@@ -54,7 +54,7 @@ module Risc
     end
     def test_pc1
       @interpreter.tick
-      assert_equal 174552 , @interpreter.pc
+      assert_equal 21688 , @interpreter.pc
     end
     def test_tick2
       @interpreter.tick
@@ -68,7 +68,7 @@ module Risc
     def test_pc2
       @interpreter.tick
       @interpreter.tick
-      assert_equal 174556 , @interpreter.pc
+      assert_equal 21692 , @interpreter.pc
     end
     def test_tick_14_jump
       14.times {@interpreter.tick}