diff --git a/junctions/src/main/scala/nasti.scala b/junctions/src/main/scala/nasti.scala
index 9eea6735..bddf5b0e 100644
--- a/junctions/src/main/scala/nasti.scala
+++ b/junctions/src/main/scala/nasti.scala
@@ -1,13 +1,20 @@
-// See LICENSE for license details.
+/// See LICENSE for license details.
 
 package junctions
 import Chisel._
 import scala.math.max
+import scala.collection.mutable.ArraySeq
+import scala.collection.mutable.HashMap
 
+case object MMIOBase extends Field[BigInt]
 case object NASTIDataBits extends Field[Int]
 case object NASTIAddrBits extends Field[Int]
 case object NASTIIdBits extends Field[Int]
 
+object bigIntPow2 {
+  def apply(in: BigInt): Boolean = in > 0 && ((in & (in-1)) == 0)
+}
+
 trait NASTIParameters extends UsesParameters {
   val nastiXDataBits = params(NASTIDataBits)
   val nastiWStrobeBits = nastiXDataBits / 8
@@ -149,3 +156,395 @@ class MemIONASTISlaveIOConverter(cacheBlockOffsetBits: Int) extends MIFModule wi
   io.nasti.r.bits.resp := UInt(0)
   io.mem.resp.ready := io.nasti.r.ready
 }
+
+class NASTIArbiter(val arbN: Int) extends NASTIModule {
+  val io = new Bundle {
+    val master = Vec.fill(arbN) { new NASTISlaveIO }
+    val slave = new NASTIMasterIO
+  }
+
+  if (arbN > 1) {
+    val arbIdBits = log2Up(arbN)
+
+    val ar_arb = Module(new RRArbiter(new NASTIReadAddressChannel, arbN))
+    val aw_arb = Module(new RRArbiter(new NASTIWriteAddressChannel, arbN))
+
+    val slave_r_arb_id = io.slave.r.bits.id(arbIdBits - 1, 0)
+    val slave_b_arb_id = io.slave.b.bits.id(arbIdBits - 1, 0)
+
+    val w_chosen = Reg(UInt(width = arbIdBits))
+    val w_done = Reg(init = Bool(true))
+
+    when (aw_arb.io.out.fire()) {
+      w_chosen := aw_arb.io.chosen
+      w_done := Bool(false)
+    }
+
+    when (io.slave.w.fire() && io.slave.w.bits.last) {
+      w_done := Bool(true)
+    }
+
+    for (i <- 0 until arbN) {
+      val m_ar = io.master(i).ar
+      val m_aw = io.master(i).aw
+      val m_r = io.master(i).r
+      val m_b = io.master(i).b
+      val a_ar = ar_arb.io.in(i)
+      val a_aw = aw_arb.io.in(i)
+      val m_w = io.master(i).w
+
+      a_ar <> m_ar
+      a_ar.bits.id := Cat(m_ar.bits.id, UInt(i, arbIdBits))
+
+      a_aw <> m_aw
+      a_aw.bits.id := Cat(m_aw.bits.id, UInt(i, arbIdBits))
+
+      m_r.valid := io.slave.r.valid && slave_r_arb_id === UInt(i)
+      m_r.bits := io.slave.r.bits
+      m_r.bits.id := io.slave.r.bits.id >> UInt(arbIdBits)
+
+      m_b.valid := io.slave.b.valid && slave_b_arb_id === UInt(i)
+      m_b.bits := io.slave.b.bits
+      m_b.bits.id := io.slave.b.bits.id >> UInt(arbIdBits)
+
+      m_w.ready := io.slave.w.ready && w_chosen === UInt(i) && !w_done
+    }
+
+    io.slave.r.ready := io.master(slave_r_arb_id).r.ready
+    io.slave.b.ready := io.master(slave_b_arb_id).b.ready
+
+    io.slave.w.bits := io.master(w_chosen).w.bits
+    io.slave.w.valid := io.master(w_chosen).w.valid && !w_done
+
+    io.slave.ar <> ar_arb.io.out
+    io.slave.aw <> aw_arb.io.out
+    aw_arb.io.out.ready := io.slave.aw.ready && w_done
+
+  } else { io.slave <> io.master.head }
+}
+
+// TODO: More efficient implementation a/la Chisel Stdlib
+class NASTIReadDataArbiter(arbN: Int) extends NASTIModule {
+  val io = new Bundle {
+    val in = Vec.fill(arbN) { Decoupled(new NASTIReadDataChannel) }.flip
+    val out = Decoupled(new NASTIReadDataChannel)
+  }
+
+  def rotateLeft[T <: Data](norm: Vec[T], rot: UInt): Vec[T] = {
+    val n = norm.size
+    Vec.tabulate(n) { i =>
+      Mux(rot < UInt(n - i), norm(UInt(i) + rot), norm(rot - UInt(n - i)))
+    }
+  }
+
+  val lockIdx = Reg(init = UInt(0, log2Up(arbN)))
+  val locked = Reg(init = Bool(false))
+
+  // use rotation to give priority to the input after the last one granted
+  val choice = PriorityMux(
+    rotateLeft(Vec(io.in.map(_.valid)), lockIdx + UInt(1)),
+    rotateLeft(Vec((0 until arbN).map(UInt(_))), lockIdx + UInt(1)))
+
+  val chosen = Mux(locked, lockIdx, choice)
+
+  for (i <- 0 until arbN) {
+    io.in(i).ready := io.out.ready && chosen === UInt(i)
+  }
+
+  io.out.valid := io.in(chosen).valid
+  io.out.bits := io.in(chosen).bits
+
+  when (io.out.fire()) {
+    when (!locked) {
+      lockIdx := choice
+      locked := !io.out.bits.last
+    } .elsewhen (io.out.bits.last) {
+      locked := Bool(false)
+    }
+  }
+}
+
+/** A slave that send decode error for every request it receives */
+class NASTIErrorSlave extends NASTIModule {
+  val io = new NASTISlaveIO
+
+  val r_queue = Module(new Queue(UInt(width = nastiRIdBits), 2))
+  r_queue.io.enq.valid := io.ar.valid
+  r_queue.io.enq.bits := io.ar.bits.id
+  io.ar.ready := r_queue.io.enq.ready
+  io.r.valid := r_queue.io.deq.valid
+  io.r.bits.id := r_queue.io.deq.bits
+  io.r.bits.resp := Bits("b11")
+  io.r.bits.last := Bool(true)
+  r_queue.io.deq.ready := io.r.ready
+
+  val draining = Reg(init = Bool(false))
+  io.w.ready := draining
+
+  when (io.aw.fire()) { draining := Bool(true) }
+  when (io.w.fire() && io.w.bits.last) { draining := Bool(false) }
+
+  val b_queue = Module(new Queue(UInt(width = nastiWIdBits), 2))
+  b_queue.io.enq.valid := io.aw.valid && !draining
+  b_queue.io.enq.bits := io.aw.bits.id
+  io.aw.ready := b_queue.io.enq.ready && !draining
+  io.b.valid := b_queue.io.deq.valid && !draining
+  io.b.bits.id := b_queue.io.deq.bits
+  io.b.bits.resp := Bits("b11")
+  b_queue.io.deq.ready := io.b.ready && !draining
+}
+
+class NASTIRouter(addrmap: Seq[(BigInt, BigInt)]) extends NASTIModule {
+  val nSlaves = addrmap.size
+
+  val io = new Bundle {
+    val master = new NASTISlaveIO
+    val slave = Vec.fill(nSlaves) { new NASTIMasterIO }
+  }
+
+  var ar_ready = Bool(false)
+  var aw_ready = Bool(false)
+  var w_ready = Bool(false)
+  var r_valid_addr = Bool(false)
+  var w_valid_addr = Bool(false)
+
+  addrmap.zip(io.slave).zipWithIndex.foreach { case (((base, size), s), i) =>
+    val bound = base + size
+
+    require(bigIntPow2(size),
+      s"Region size $size is not a power of 2")
+    require(base % size == 0,
+      f"Region base address $base%x not divisible by $size%d" )
+
+    val ar_addr = io.master.ar.bits.addr
+    val ar_match = ar_addr >= UInt(base) && ar_addr < UInt(bound)
+
+    s.ar.valid := io.master.ar.valid && ar_match
+    s.ar.bits := io.master.ar.bits
+    ar_ready = ar_ready || (s.ar.ready && ar_match)
+    r_valid_addr = r_valid_addr || ar_match
+
+    val aw_addr = io.master.aw.bits.addr
+    val aw_match = aw_addr >= UInt(base) && aw_addr < UInt(bound)
+
+    s.aw.valid := io.master.aw.valid && aw_match
+    s.aw.bits := io.master.aw.bits
+    aw_ready = aw_ready || (s.aw.ready && aw_match)
+    w_valid_addr = w_valid_addr || aw_match
+
+    val chosen = Reg(init = Bool(false))
+    when (s.aw.fire()) { chosen := Bool(true) }
+    when (s.w.fire() && s.w.bits.last) { chosen := Bool(false) }
+
+    s.w.valid := io.master.w.valid && chosen
+    s.w.bits := io.master.w.bits
+    w_ready = w_ready || (s.w.ready && chosen)
+  }
+
+  val err_slave = Module(new NASTIErrorSlave)
+  err_slave.io.ar.valid := !r_valid_addr && io.master.ar.valid
+  err_slave.io.ar.bits := io.master.ar.bits
+  err_slave.io.aw.valid := !w_valid_addr && io.master.aw.valid
+  err_slave.io.aw.bits := io.master.aw.bits
+  err_slave.io.w.valid := io.master.w.valid
+  err_slave.io.w.bits := io.master.w.bits
+
+  io.master.ar.ready := ar_ready || (!r_valid_addr && err_slave.io.ar.ready)
+  io.master.aw.ready := aw_ready || (!w_valid_addr && err_slave.io.aw.ready)
+  io.master.w.ready := w_ready || err_slave.io.w.ready
+
+  val b_arb = Module(new RRArbiter(new NASTIWriteResponseChannel, nSlaves + 1))
+  val r_arb = Module(new NASTIReadDataArbiter(nSlaves + 1))
+
+  for (i <- 0 until nSlaves) {
+    b_arb.io.in(i) <> io.slave(i).b
+    r_arb.io.in(i) <> io.slave(i).r
+  }
+
+  b_arb.io.in(nSlaves) <> err_slave.io.b
+  r_arb.io.in(nSlaves) <> err_slave.io.r
+
+  io.master.b <> b_arb.io.out
+  io.master.r <> r_arb.io.out
+}
+
+class NASTICrossbar(nMasters: Int, nSlaves: Int, addrmap: Seq[(BigInt, BigInt)])
+    extends NASTIModule {
+  val io = new Bundle {
+    val masters = Vec.fill(nMasters) { new NASTISlaveIO }
+    val slaves = Vec.fill(nSlaves) { new NASTIMasterIO }
+  }
+
+  val routers = Vec.fill(nMasters) { Module(new NASTIRouter(addrmap)).io }
+  val arbiters = Vec.fill(nSlaves) { Module(new NASTIArbiter(nMasters)).io }
+
+  for (i <- 0 until nMasters) {
+    routers(i).master <> io.masters(i)
+  }
+
+  for (i <- 0 until nSlaves) {
+    arbiters(i).master <> Vec(routers.map(r => r.slave(i)))
+    io.slaves(i) <> arbiters(i).slave
+  }
+}
+
+case object NASTINMasters extends Field[Int]
+case object NASTINSlaves extends Field[Int]
+
+object AddrMapTypes {
+  type AddrMapEntry = (String, Option[BigInt], MemRegion)
+  type AddrMap = Seq[AddrMapEntry]
+}
+import AddrMapTypes._
+
+abstract class MemRegion { def size: BigInt }
+
+case class MemSize(size: BigInt) extends MemRegion
+case class MemSubmap(size: BigInt, entries: AddrMap) extends MemRegion
+
+object Submap {
+  def apply(size: BigInt, entries: AddrMapEntry*) =
+    new MemSubmap(size, entries)
+}
+
+case class AddrHashMapEntry(port: Int, start: BigInt, size: BigInt)
+
+class AddrHashMap(addrmap: AddrMap) {
+  val mapping = new HashMap[String, AddrHashMapEntry]
+
+  private def genPairs(addrmap: AddrMap): Seq[(String, AddrHashMapEntry)] = {
+    var ind = 0
+    var base = BigInt(0)
+    var pairs = Seq[(String, AddrHashMapEntry)]()
+    addrmap.foreach { case (name, startOpt, region) =>
+      region match {
+        case MemSize(size) => {
+          if (!startOpt.isEmpty) base = startOpt.get
+          pairs = (name, AddrHashMapEntry(ind, base, size)) +: pairs
+          base += size
+          ind += 1
+        }
+        case MemSubmap(size, submap) => {
+          if (!startOpt.isEmpty) base = startOpt.get
+          val subpairs = genPairs(submap).map {
+            case (subname, AddrHashMapEntry(subind, subbase, subsize)) =>
+              (name + ":" + subname,
+                AddrHashMapEntry(ind + subind, base + subbase, subsize))
+          }
+          pairs = subpairs ++ pairs
+          ind += subpairs.size
+          base += size
+        }
+      }
+    }
+    pairs
+  }
+
+  for ((name, ind) <- genPairs(addrmap)) { mapping(name) = ind }
+
+  def nEntries: Int = mapping.size
+  def apply(name: String): AddrHashMapEntry = mapping(name)
+  def get(name: String): Option[AddrHashMapEntry] = mapping.get(name)
+  def sortedEntries(): Seq[(String, BigInt, BigInt)] = {
+    val arr = new Array[(String, BigInt, BigInt)](mapping.size)
+    mapping.foreach { case (name, AddrHashMapEntry(port, base, size)) =>
+      arr(port) = (name, base, size)
+    }
+    arr.toSeq
+  }
+}
+
+case object NASTIAddrMap extends Field[AddrMap]
+case object NASTIAddrHashMap extends Field[AddrHashMap]
+
+class NASTIInterconnectIO(val nMasters: Int, val nSlaves: Int) extends Bundle {
+  /* This is a bit confusing. The interconnect is a slave to the masters and
+   * a master to the slaves. Hence why the declarations seem to be backwards. */
+  val masters = Vec.fill(nMasters) { new NASTISlaveIO }
+  val slaves = Vec.fill(nSlaves) { new NASTIMasterIO }
+  override def cloneType =
+    new NASTIInterconnectIO(nMasters, nSlaves).asInstanceOf[this.type]
+}
+
+abstract class NASTIInterconnect extends NASTIModule {
+  val nMasters: Int
+  val nSlaves: Int
+
+  lazy val io = new NASTIInterconnectIO(nMasters, nSlaves)
+}
+
+class NASTIRecursiveInterconnect(
+    val nMasters: Int, val nSlaves: Int,
+    addrmap: AddrMap, base: BigInt = 0) extends NASTIInterconnect {
+
+  private def mapCountSlaves(addrmap: AddrMap): Int = {
+    addrmap.map {
+      case (_, _, MemSize(_)) => 1
+      case (_, _, MemSubmap(_, submap)) => mapCountSlaves(submap)
+    }.reduceLeft(_ + _)
+  }
+
+  var lastEnd = base
+  var slaveInd = 0
+  val levelSize = addrmap.size
+
+  val realAddrMap = new ArraySeq[(BigInt, BigInt)](addrmap.size)
+
+  addrmap.zipWithIndex.foreach { case ((_, startOpt, region), i) =>
+    val start = startOpt.getOrElse(lastEnd)
+    val size = region.size
+    realAddrMap(i) = (start, size)
+    lastEnd = start + size
+  }
+
+  val flatSlaves = if (nMasters > 1) {
+    val xbar = Module(new NASTICrossbar(nMasters, levelSize, realAddrMap))
+    xbar.io.masters <> io.masters
+    xbar.io.slaves
+  } else {
+    val router = Module(new NASTIRouter(realAddrMap))
+    router.io.master <> io.masters.head
+    router.io.slave
+  }
+
+  addrmap.zip(realAddrMap).zipWithIndex.foreach {
+    case (((_, _, region), (start, size)), i) => {
+      region match {
+        case MemSize(_) =>
+          io.slaves(slaveInd) <> flatSlaves(i)
+          slaveInd += 1
+        case MemSubmap(_, submap) =>
+          val subSlaves = mapCountSlaves(submap)
+          val ic = Module(new NASTIRecursiveInterconnect(
+            1, subSlaves, submap, start))
+          ic.io.masters.head <> flatSlaves(i)
+          io.slaves.drop(slaveInd).take(subSlaves).zip(ic.io.slaves).foreach {
+            case (s, m) => s <> m
+          }
+          slaveInd += subSlaves
+      }
+    }
+  }
+}
+
+class NASTITopInterconnect extends NASTIInterconnect {
+  val nMasters = params(NASTINMasters)
+  val nSlaves = params(NASTINSlaves)
+
+  bigIntPow2(params(MMIOBase))
+
+  val temp = Module(new NASTIRecursiveInterconnect(
+    nMasters, nSlaves, params(NASTIAddrMap)))
+
+  temp.io.masters.zip(io.masters).foreach { case (t, i) =>
+    t.ar <> i.ar
+    t.aw <> i.aw
+    // this queue is necessary to break up the aw - w dependence
+    // introduced by the TileLink -> NASTI converter
+    t.w <> Queue(i.w)
+    i.b <> t.b
+    i.r <> t.r
+  }
+  //temp.io.masters <> io.masters
+  io.slaves <> temp.io.slaves
+}