articulate device types

src/main/scala/com/htmlism/mos6502/dsl/Address.scala

@@ -1,6 +1,8 @@
 package com.htmlism.mos6502.dsl
 
-sealed trait Address
+sealed trait Address {
+  def n: Int
+}
 
 object ZeroAddress {
   implicit val operandZero: Operand[ZeroAddress] =

src/main/scala/com/htmlism/mos6502/dsl/ReadWriteDevice.scala

@@ -0,0 +1,15 @@
+package com.htmlism.mos6502.dsl
+
+//import com.htmlism.mos6502.model._
+
+case class ReadWriteDevice[A](address: Address) {
+  def read(implicit ctx: AssemblyContext): Unit = {
+    val _ = ctx
+//    ctx.push(LDA, ev, s"write ${ev.toShow(x)} to $name ($n)")
+  }
+
+  def write(implicit ctx: AssemblyContext): Unit = {
+    val _ = ctx
+    //    ctx.push(STA, ev, s"write ${ev.toShow(x)} to $name ($n)")
+  }
+}

src/main/scala/com/htmlism/mos6502/dsl/VolatileDevice.scala

@@ -0,0 +1,10 @@
+package com.htmlism.mos6502.dsl
+
+//import com.htmlism.mos6502.model._
+
+case class VolatileDevice[A](address: Address) {
+  def read(implicit ctx: AssemblyContext): Unit = {
+    val _ = ctx
+//    ctx.push(LDA, ev, s"write ${ev.toShow(x)} to $name ($n)")
+  }
+}

src/test/scala/com/htmlism/mos6502/dsl/snake/Easy6502Spec.scala

@@ -68,6 +68,9 @@ class Easy6502Spec extends AnyFlatSpec with should.Matchers {
   }
 
   "snake" should "compile" in {
+    val sysRandom = VolatileDevice[Int](0xfe.addr)
+    val sysLastKey = VolatileDevice[AsciiValue](0xff.addr)
+
     val initSnake =
       sub("initSnake") { implicit a =>
         registers.X.incr
@@ -130,6 +133,9 @@ class Easy6502Spec extends AnyFlatSpec with should.Matchers {
         mapping[AsciiValue]
 
         asm { implicit a =>
+          sysRandom.read
+          sysLastKey.read
+
           jump(init)
           jump(loop)
         }