add cpu module

build.sbt

@@ -3,7 +3,7 @@ lazy val firepower =
     .in(file("."))
     .withCats
     .withTesting
-    .aggregate(nescant, core, demo)
+    .aggregate(nescant, core, cpu, demo)
 
 lazy val nescant =
   project.withCats.withTesting
@@ -13,6 +13,11 @@ lazy val core =
     .withCats
     .withTesting
 
+lazy val cpu =
+  module("cpu")
+    .settings(description := "CPU emulation suitable for unit testing")
+    .withTesting
+
 lazy val demo =
   module("demo")
     .dependsOn(core)