diff --git a/Makefrag b/Makefrag
index a8335606..e05f6d69 100644
--- a/Makefrag
+++ b/Makefrag
@@ -49,12 +49,13 @@ bootrom_img = $(base_dir)/bootrom/bootrom.img
 # Constants Header Files
 #---------------------------------------------------------------------
 
+# sed uses -E (instead of -r) for BSD support
 params_file = $(generated_dir)/$(MODEL).$(CONFIG).prm
 consts_header = $(generated_dir)/consts.$(CONFIG).h
 $(consts_header): $(params_file)
 	echo "#ifndef __CONST_H__" > $@
 	echo "#define __CONST_H__" >> $@
-	sed -r 's/\(([A-Za-z0-9_]+),([A-Za-z0-9_]+)\)/#define \1 \2/' $< >> $@
+	sed -E 's/\(([A-Za-z0-9_]+),([A-Za-z0-9_]+)\)/#define \1 \2/' $< >> $@
 	echo "#endif // __CONST_H__" >> $@
 
 params_file_debug = $(generated_dir_debug)/$(MODEL).$(CONFIG).prm
@@ -62,7 +63,7 @@ consts_header_debug = $(generated_dir_debug)/consts.$(CONFIG).h
 $(consts_header_debug): $(params_file_debug)
 	echo "#ifndef __CONST_H__" > $@
 	echo "#define __CONST_H__" >> $@
-	sed -r 's/\(([A-Za-z0-9_]+),([A-Za-z0-9_]+)\)/#define \1 \2/' $< >> $@
+	sed -E 's/\(([A-Za-z0-9_]+),([A-Za-z0-9_]+)\)/#define \1 \2/' $< >> $@
 	echo "#endif // __CONST_H__" >> $@
 
 clean-run-output:
diff --git a/csrc/emulator.cc b/csrc/emulator.cc
index a6b04de1..db914704 100644
--- a/csrc/emulator.cc
+++ b/csrc/emulator.cc
@@ -98,14 +98,14 @@ int main(int argc, char** argv)
 #if VM_TRACE
     bool dump = tfp && trace_count >= start;
     if (dump)
-      tfp->dump(trace_count * 2);
+      tfp->dump(static_cast<vluint64_t>(trace_count * 2));
 #endif
 
     tile->clk = 1;
     tile->eval();
 #if VM_TRACE
     if (dump)
-      tfp->dump(trace_count * 2 + 1);
+      tfp->dump(static_cast<vluint64_t>(trace_count * 2 + 1));
 #endif
     trace_count++;
   }
diff --git a/firrtl b/firrtl
index 6a05468e..7c38199c 160000
--- a/firrtl
+++ b/firrtl
@@ -1 +1 @@
-Subproject commit 6a05468ed0ece1ace3019666b16f2ae83ef76ef9
+Subproject commit 7c38199ce7a5d9dd7e27ffbb9b2b2770b972ed94
diff --git a/src/main/scala/coreplex/Coreplex.scala b/src/main/scala/coreplex/Coreplex.scala
index 70d1343b..2ccad311 100644
--- a/src/main/scala/coreplex/Coreplex.scala
+++ b/src/main/scala/coreplex/Coreplex.scala
@@ -59,7 +59,7 @@ abstract class Coreplex(implicit val p: Parameters, implicit val c: CoreplexConf
     val slave = Vec(c.nSlaves, new ClientUncachedTileLinkIO()(innerParams)).flip
     val interrupts = Vec(c.nExtInterrupts, Bool()).asInput
     val debug = new DebugBusIO()(p).flip
-    val rtcTick = Bool(INPUT)
+    val prci = Vec(c.nTiles, new PRCITileIO).flip
     val success: Option[Bool] = hasSuccessFlag.option(Bool(OUTPUT))
   }
 
@@ -170,21 +170,14 @@ class DefaultCoreplex(tp: Parameters, tc: CoreplexConfig) extends Coreplex()(tp,
     debugModule.io.tl <> mmioNetwork.port("int:debug")
     debugModule.io.db <> io.debug
 
-    val prci = Module(new PRCI)
-    prci.io.tl <> mmioNetwork.port("int:prci")
-    prci.io.rtcTick := io.rtcTick
-
-    (prci.io.tiles, tileResets, tileList).zipped.foreach {
-      case (prci, rst, tile) =>
-        rst := reset
-        tile.io.prci <> prci
-    }
-
-    for (i <- 0 until tc.nTiles) {
-      prci.io.interrupts(i).meip := plic.io.harts(plic.cfg.context(i, 'M'))
-      if (p(UseVM))
-        prci.io.interrupts(i).seip := plic.io.harts(plic.cfg.context(i, 'S'))
-      prci.io.interrupts(i).debug := debugModule.io.debugInterrupts(i)
+    // connect coreplex-internal interrupts to tiles
+    for (((tile, tileReset), i) <- (tileList zip tileResets) zipWithIndex) {
+      tileReset := io.prci(i).reset
+      tile.io.interrupts := io.prci(i).interrupts
+      tile.io.interrupts.meip := plic.io.harts(plic.cfg.context(i, 'M'))
+      tile.io.interrupts.seip.foreach(_ := plic.io.harts(plic.cfg.context(i, 'S')))
+      tile.io.interrupts.debug := debugModule.io.debugInterrupts(i)
+      tile.io.hartid := i
     }
 
     val tileSlavePorts = (0 until tc.nTiles) map (i => s"int:dmem$i") filter (ioAddrMap contains _)
diff --git a/src/main/scala/coreplex/UnitTest.scala b/src/main/scala/coreplex/UnitTest.scala
index b308b2e1..ca8e66da 100644
--- a/src/main/scala/coreplex/UnitTest.scala
+++ b/src/main/scala/coreplex/UnitTest.scala
@@ -7,10 +7,14 @@ import uncore.tilelink.TLId
 import cde.Parameters
 
 class UnitTestCoreplex(tp: Parameters, tc: CoreplexConfig) extends Coreplex()(tp, tc) {
-  require(!tc.hasExtMMIOPort)
   require(tc.nSlaves == 0)
   require(tc.nMemChannels == 0)
 
+  io.master.mmio.foreach { port =>
+    port.acquire.valid := Bool(false)
+    port.grant.ready := Bool(false)
+  }
+
   io.debug.req.ready := Bool(false)
   io.debug.resp.valid := Bool(false)
 
diff --git a/src/main/scala/junctions/crossing.scala b/src/main/scala/junctions/crossing.scala
index 4a17fde7..4e8e4227 100644
--- a/src/main/scala/junctions/crossing.scala
+++ b/src/main/scala/junctions/crossing.scala
@@ -83,5 +83,44 @@ object AsyncIrrevocableFrom
   // takes from_source from the 'from' clock domain and puts it into your clock domain
   def apply[T <: Data](from_clock: Clock, from_reset: Bool, from_source: ReadyValidIO[T], depth: Int = 8, sync: Int = 3): IrrevocableIO[T] = {
     PostQueueIrrevocablize(AsyncDecoupledFrom(from_clock, from_reset, from_source, depth, sync))
+}
+
+/**  Because Chisel/FIRRTL does not allow us
+  *  to directly assign clocks from Signals,
+  *  we need this black box module.
+  *  This may even be useful because some back-end
+  *  flows like to have this sort of transition
+  *  flagged with a special cell or module anyway.
+  */
+
+class SignalToClock extends BlackBox {
+  val io = new Bundle {
+    val signal_in = Bool(INPUT)
+    val clock_out = Clock(OUTPUT)
+  }
+
+  //  io.clock_out := io.signal_in
+}
+
+object SignalToClock {
+  def apply(signal: Bool): Clock = {
+    val s2c = Module(new SignalToClock)
+    s2c.io.signal_in := signal
+    s2c.io.clock_out
+  }
+}
+
+class ClockToSignal extends BlackBox {
+  val io = new Bundle {
+    val clock_in = Clock(INPUT)
+    val signal_out = Bool(OUTPUT)
+  }
+}
+
+object ClockToSignal {
+  def apply(clk: Clock): Bool = {
+    val c2s = Module(new ClockToSignal)
+    c2s.io.clock_in := clk
+    c2s.io.signal_out
   }
 }
diff --git a/src/main/scala/junctions/hasti.scala b/src/main/scala/junctions/hasti.scala
index 6063729e..9a36048f 100644
--- a/src/main/scala/junctions/hasti.scala
+++ b/src/main/scala/junctions/hasti.scala
@@ -521,10 +521,8 @@ class HastiTestSRAM(depth: Int)(implicit p: Parameters) extends HastiModule()(p)
   // In case we are stalled, we need to hold the read data
   val d_rdata = holdUnless(mem.read(a_address, read), RegNext(read))
   // Whenever the port is not needed for reading, execute pending writes
-  when (!read) {
-    when (p_valid) { mem.write(p_address, p_wdata, p_mask.toBools) }
-    p_valid := Bool(false)
-  }
+  when (!read && p_valid) { mem.write(p_address, p_wdata, p_mask.toBools) }
+  when (!read) { p_valid := Bool(false) }
   
   // Record the request for later?
   when (ready && a_request && a_write) {
diff --git a/src/main/scala/rocket/csr.scala b/src/main/scala/rocket/csr.scala
index e75edb47..8b3ecff0 100644
--- a/src/main/scala/rocket/csr.scala
+++ b/src/main/scala/rocket/csr.scala
@@ -61,6 +61,14 @@ class DCSR extends Bundle {
   val prv = UInt(width = PRV.SZ)
 }
 
+class TileInterrupts(implicit p: Parameters) extends CoreBundle()(p) {
+  val debug = Bool()
+  val mtip = Bool()
+  val msip = Bool()
+  val meip = Bool()
+  val seip = usingVM.option(Bool())
+}
+
 class MIP extends Bundle {
   val rocc = Bool()
   val meip = Bool()
@@ -121,7 +129,8 @@ object CSR
 }
 
 class CSRFileIO(implicit p: Parameters) extends CoreBundle {
-  val prci = new PRCITileIO().flip
+  val interrupts = new TileInterrupts().asInput
+  val hartid = UInt(INPUT, xLen)
   val rw = new Bundle {
     val addr = UInt(INPUT, CSR.ADDRSZ)
     val cmd = Bits(INPUT, CSR.SZ)
@@ -297,7 +306,7 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
     CSRs.mepc -> reg_mepc.sextTo(xLen),
     CSRs.mbadaddr -> reg_mbadaddr.sextTo(xLen),
     CSRs.mcause -> reg_mcause,
-    CSRs.mhartid -> io.prci.id)
+    CSRs.mhartid -> io.hartid)
 
   val debug_csrs = collection.immutable.ListMap(
     CSRs.dcsr -> reg_dcsr.asUInt,
@@ -611,8 +620,8 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
     }
   }
 
-  reg_mip := io.prci.interrupts
-  reg_dcsr.debugint := io.prci.interrupts.debug
+  reg_mip := io.interrupts
+  reg_dcsr.debugint := io.interrupts.debug
 
   reg_sptbr.asid := 0
   if (nBreakpoints <= 1) reg_tselect := 0
diff --git a/src/main/scala/rocket/rocket.scala b/src/main/scala/rocket/rocket.scala
index 6fa6893a..61b013b2 100644
--- a/src/main/scala/rocket/rocket.scala
+++ b/src/main/scala/rocket/rocket.scala
@@ -143,7 +143,8 @@ object ImmGen {
 
 class Rocket(implicit p: Parameters) extends CoreModule()(p) {
   val io = new Bundle {
-    val prci = new PRCITileIO().flip
+    val interrupts = new TileInterrupts().asInput
+    val hartid = UInt(INPUT, xLen)
     val imem  = new FrontendIO()(p.alterPartial({case CacheName => "L1I" }))
     val dmem = new HellaCacheIO()(p.alterPartial({ case CacheName => "L1D" }))
     val ptw = new DatapathPTWIO().flip
@@ -514,7 +515,8 @@ class Rocket(implicit p: Parameters) extends CoreModule()(p) {
   csr.io.exception := wb_reg_xcpt
   csr.io.cause := wb_reg_cause
   csr.io.retire := wb_valid
-  csr.io.prci <> io.prci
+  csr.io.interrupts := io.interrupts
+  csr.io.hartid := io.hartid
   io.fpu.fcsr_rm := csr.io.fcsr_rm
   csr.io.fcsr_flags := io.fpu.fcsr_flags
   csr.io.rocc.interrupt <> io.rocc.interrupt
@@ -681,7 +683,7 @@ class Rocket(implicit p: Parameters) extends CoreModule()(p) {
   }
   else {
     printf("C%d: %d [%d] pc=[%x] W[r%d=%x][%d] R[r%d=%x] R[r%d=%x] inst=[%x] DASM(%x)\n",
-         io.prci.id, csr.io.time(31,0), wb_valid, wb_reg_pc,
+         io.hartid, csr.io.time(31,0), wb_valid, wb_reg_pc,
          Mux(rf_wen, rf_waddr, UInt(0)), rf_wdata, rf_wen,
          wb_reg_inst(19,15), Reg(next=Reg(next=ex_rs(0))),
          wb_reg_inst(24,20), Reg(next=Reg(next=ex_rs(1))),
diff --git a/src/main/scala/rocket/tile.scala b/src/main/scala/rocket/tile.scala
index df055f90..1a868fa8 100644
--- a/src/main/scala/rocket/tile.scala
+++ b/src/main/scala/rocket/tile.scala
@@ -31,7 +31,8 @@ abstract class Tile(clockSignal: Clock = null, resetSignal: Bool = null)
   class TileIO extends Bundle {
     val cached = Vec(nCachedTileLinkPorts, new ClientTileLinkIO)
     val uncached = Vec(nUncachedTileLinkPorts, new ClientUncachedTileLinkIO)
-    val prci = new PRCITileIO().flip
+    val hartid = UInt(INPUT, p(XLen))
+    val interrupts = new TileInterrupts().asInput
     val slave = (p(DataScratchpadSize) > 0).option(new ClientUncachedTileLinkIO().flip)
   }
 
@@ -54,7 +55,8 @@ class RocketTile(clockSignal: Clock = null, resetSignal: Bool = null)
   val uncachedArbPorts = collection.mutable.ArrayBuffer(icache.io.mem)
   val uncachedPorts = collection.mutable.ArrayBuffer[ClientUncachedTileLinkIO]()
   val cachedPorts = collection.mutable.ArrayBuffer(dcache.mem)
-  core.io.prci <> io.prci
+  core.io.interrupts := io.interrupts
+  core.io.hartid := io.hartid
   icache.io.cpu <> core.io.imem
 
   val fpuOpt = p(FPUKey).map(cfg => Module(new FPU(cfg)))
diff --git a/src/main/scala/rocketchip/Periphery.scala b/src/main/scala/rocketchip/Periphery.scala
index 50fa150f..cdf6e5fd 100644
--- a/src/main/scala/rocketchip/Periphery.scala
+++ b/src/main/scala/rocketchip/Periphery.scala
@@ -276,6 +276,33 @@ trait PeripherySlaveModule extends HasPeripheryParameters {
 
 /////
 
+/** Always-ON block */
+trait PeripheryAON extends LazyModule {
+  implicit val p: Parameters
+  val pDevices: ResourceManager[AddrMapEntry]
+
+  pDevices.add(AddrMapEntry("prci", MemSize(0x4000000, MemAttr(AddrMapProt.RW))))
+}
+
+trait PeripheryAONBundle {
+  implicit val p: Parameters
+}
+
+trait PeripheryAONModule extends HasPeripheryParameters {
+  implicit val p: Parameters
+  val outer: PeripheryAON
+  val io: PeripheryAONBundle
+  val mmioNetwork: Option[TileLinkRecursiveInterconnect]
+  val coreplex: Coreplex
+
+  val prci = Module(new PRCI()(innerMMIOParams))
+  prci.io.rtcTick := Counter(p(RTCPeriod)).inc()
+  prci.io.tl <> mmioNetwork.get.port("prci")
+  coreplex.io.prci <> prci.io.tiles
+}
+
+/////
+
 trait PeripheryTestRAM extends LazyModule {
   implicit val p: Parameters
   val pDevices: ResourceManager[AddrMapEntry]
diff --git a/src/main/scala/rocketchip/Top.scala b/src/main/scala/rocketchip/Top.scala
index 7dfdb0bc..ca239673 100644
--- a/src/main/scala/rocketchip/Top.scala
+++ b/src/main/scala/rocketchip/Top.scala
@@ -66,7 +66,6 @@ class BaseTopModule[+L <: BaseTop, +B <: BaseTopBundle](val p: Parameters, l: L,
   val io: B = b(coreplex)
 
   io.success zip coreplex.io.success map { case (x, y) => x := y }
-  coreplex.io.rtcTick := Counter(p(RTCPeriod)).inc()
 
   val mmioNetwork = c.hasExtMMIOPort.option(
     Module(new TileLinkRecursiveInterconnect(1, p(GlobalAddrMap).get.subMap("io:ext"))(
@@ -76,17 +75,17 @@ class BaseTopModule[+L <: BaseTop, +B <: BaseTopBundle](val p: Parameters, l: L,
 
 /** Example Top with Periphery */
 class ExampleTop(p: Parameters) extends BaseTop(p)
-    with PeripheryDebug with PeripheryExtInterrupts
+    with PeripheryDebug with PeripheryExtInterrupts with PeripheryAON
     with PeripheryMasterMem with PeripheryMasterMMIO with PeripherySlave {
   override lazy val module = Module(new ExampleTopModule(p, this, new ExampleTopBundle(p, _)))
 }
 
 class ExampleTopBundle(p: Parameters, c: Coreplex) extends BaseTopBundle(p, c)
-    with PeripheryDebugBundle with PeripheryExtInterruptsBundle
+    with PeripheryDebugBundle with PeripheryExtInterruptsBundle with PeripheryAONBundle
     with PeripheryMasterMemBundle with PeripheryMasterMMIOBundle with PeripherySlaveBundle
 
 class ExampleTopModule[+L <: ExampleTop, +B <: ExampleTopBundle](p: Parameters, l: L, b: Coreplex => B) extends BaseTopModule(p, l, b)
-    with PeripheryDebugModule with PeripheryExtInterruptsModule
+    with PeripheryDebugModule with PeripheryExtInterruptsModule with PeripheryAONModule
     with PeripheryMasterMemModule with PeripheryMasterMMIOModule with PeripherySlaveModule
 
 /** Example Top with TestRAM */
diff --git a/src/main/scala/rocketchip/Utils.scala b/src/main/scala/rocketchip/Utils.scala
index 1f4765a2..b07a91b2 100644
--- a/src/main/scala/rocketchip/Utils.scala
+++ b/src/main/scala/rocketchip/Utils.scala
@@ -54,7 +54,6 @@ object GenerateGlobalAddrMap {
       entries += AddrMapEntry("debug", MemSize(4096, MemAttr(AddrMapProt.RWX)))
       entries += AddrMapEntry("bootrom", MemSize(4096, MemAttr(AddrMapProt.RX)))
       entries += AddrMapEntry("plic", MemRange(0x40000000, 0x4000000, MemAttr(AddrMapProt.RW)))
-      entries += AddrMapEntry("prci", MemSize(0x4000000, MemAttr(AddrMapProt.RW)))
       if (p(DataScratchpadSize) > 0) { // TODO heterogeneous tiles
         require(p(NTiles) == 1) // TODO relax this
         require(p(NMemoryChannels) == 0) // TODO allow both scratchpad & DRAM
@@ -84,7 +83,7 @@ object GenerateConfigString {
   def apply(p: Parameters, c: CoreplexConfig, pDevicesEntries: Seq[AddrMapEntry]) = {
     val addrMap = p(GlobalAddrMap).get
     val plicAddr = addrMap("io:int:plic").start
-    val prciAddr = addrMap("io:int:prci").start
+    val prciAddr = addrMap("io:ext:prci").start
     val xLen = p(XLen)
     val res = new StringBuilder
     res append  "plic {\n"
diff --git a/src/main/scala/uncore/devices/Prci.scala b/src/main/scala/uncore/devices/Prci.scala
index 24232fd8..d607be91 100644
--- a/src/main/scala/uncore/devices/Prci.scala
+++ b/src/main/scala/uncore/devices/Prci.scala
@@ -13,21 +13,11 @@ import cde.{Parameters, Field}
 /** Number of tiles */
 case object NTiles extends Field[Int]
 
-class PRCIInterrupts extends Bundle {
-  val meip = Bool()
-  val seip = Bool()
-  val debug = Bool()
-}
-
 class PRCITileIO(implicit p: Parameters) extends Bundle {
   val reset = Bool(OUTPUT)
-  val id = UInt(OUTPUT, log2Up(p(NTiles)))
-  val interrupts = {
-    val result = new PRCIInterrupts {
-      val mtip = Bool()
-      val msip = Bool()
-    }
-    result.asOutput
+  val interrupts = new Bundle {
+    val mtip = Bool()
+    val msip = Bool()
   }
 
   override def cloneType: this.type = new PRCITileIO().asInstanceOf[this.type]
@@ -47,7 +37,6 @@ class PRCI(implicit val p: Parameters) extends Module
     with HasTileLinkParameters
     with HasAddrMapParameters {
   val io = new Bundle {
-    val interrupts = Vec(p(NTiles), new PRCIInterrupts).asInput
     val tl = new ClientUncachedTileLinkIO().flip
     val tiles = Vec(p(NTiles), new PRCITileIO)
     val rtcTick = Bool(INPUT)
@@ -84,10 +73,9 @@ class PRCI(implicit val p: Parameters) extends Module
   }
 
   for ((tile, i) <- io.tiles zipWithIndex) {
-    tile.interrupts := io.interrupts(i)
     tile.interrupts.msip := ipi(i)(0)
     tile.interrupts.mtip := time >= timecmp(i)
-    tile.id := UInt(i)
+    tile.reset := reset
   }
 
   // TODO generalize these to help other TL slaves
diff --git a/src/main/scala/uncore/tilelink2/RegisterCrossing.scala b/src/main/scala/uncore/tilelink2/RegisterCrossing.scala
index 843c559e..3c11bbca 100644
--- a/src/main/scala/uncore/tilelink2/RegisterCrossing.scala
+++ b/src/main/scala/uncore/tilelink2/RegisterCrossing.scala
@@ -5,6 +5,7 @@ package uncore.tilelink2
 import Chisel._
 import chisel3.util.{Irrevocable, IrrevocableIO}
 import junctions._
+import uncore.util.{AsyncResetRegVec}
 
 // A very simple flow control state machine, run in the specified clock domain
 class BusyRegisterCrossing(clock: Clock, reset: Bool)
@@ -131,3 +132,56 @@ class RegisterReadCrossing[T <: Data](gen: T, sync: Int = 3) extends Module {
   crossing.io.deq.ready := io.master_port.request.valid && !reg.io.busy
   crossing.io.enq.valid := Bool(true)
 }
+
+/** Wrapper to create an
+  *  asynchronously reset
+  *  slave register which
+  *  can be both read
+  *  and written using
+  *  crossing FIFOs.
+  */
+
+object AsyncRWSlaveRegField {
+
+  def apply(slave_clock: Clock,
+    slave_reset: Bool,
+    width:  Int,
+    init: Int,
+    master_allow: Bool = Bool(true),
+    slave_allow: Bool = Bool(true)
+  ): (UInt, RegField) = {
+
+    val async_slave_reg = Module(new AsyncResetRegVec(width, init))
+    async_slave_reg.reset := slave_reset
+    async_slave_reg.clock := slave_clock
+
+    val wr_crossing = Module (new RegisterWriteCrossing(UInt(width = width)))
+
+    val scope = Module (new AsyncScope())
+
+    wr_crossing.io.master_clock := scope.clock
+    wr_crossing.io.master_reset := scope.reset
+    wr_crossing.io.master_allow := master_allow
+    wr_crossing.io.slave_clock  := slave_clock
+    wr_crossing.io.slave_reset  := slave_reset
+    wr_crossing.io.slave_allow  := slave_allow
+
+    async_slave_reg.io.en := wr_crossing.io.slave_valid
+    async_slave_reg.io.d  := wr_crossing.io.slave_register
+
+    val rd_crossing = Module (new RegisterReadCrossing(UInt(width = width )))
+
+    rd_crossing.io.master_clock := scope.clock
+    rd_crossing.io.master_reset := scope.reset
+    rd_crossing.io.master_allow := master_allow
+    rd_crossing.io.slave_clock  := slave_clock
+    rd_crossing.io.slave_reset  := slave_reset
+    rd_crossing.io.slave_allow  := slave_allow
+
+    rd_crossing.io.slave_register := async_slave_reg.io.q
+
+    (async_slave_reg.io.q, RegField(width, rd_crossing.io.master_port, wr_crossing.io.master_port))
+
+  }
+
+}
diff --git a/vsim/Makefrag b/vsim/Makefrag
index 3abb2b4e..31ee449b 100644
--- a/vsim/Makefrag
+++ b/vsim/Makefrag
@@ -7,7 +7,11 @@
 bb_vsrcs = $(base_dir)/vsrc/DebugTransportModuleJtag.v \
 	$(base_dir)/vsrc/jtag_vpi.v \
 	$(base_dir)/vsrc/AsyncMailbox.v \
-	$(base_dir)/vsrc/AsyncResetReg.v
+	$(base_dir)/vsrc/AsyncResetReg.v \
+	$(base_dir)/vsrc/ClockDivider.v \
+        $(base_dir)/vsrc/ClockToSignal.v \
+        $(base_dir)/vsrc/SignalToClock.v \
+        
 
 sim_vsrcs = \
 	$(generated_dir)/$(MODEL).$(CONFIG).v \
diff --git a/vsrc/ClockToSignal.v b/vsrc/ClockToSignal.v
new file mode 100644
index 00000000..db8b8b37
--- /dev/null
+++ b/vsrc/ClockToSignal.v
@@ -0,0 +1,19 @@
+  
+/* This blackbox is needed by 
+ * Chisel in order to do type conversion.
+ * It may be useful for some synthesis flows
+ * as well which require special 
+ * flagging on conversion from data to clock.
+ */
+
+
+module ClockToSignal(
+             output signal_out,
+             input  clock_in
+                      );
+   
+
+  assign signal_out = clock_in;
+                       
+endmodule // ClockToSignal
+
diff --git a/vsrc/SignalToClock.v b/vsrc/SignalToClock.v
new file mode 100644
index 00000000..553bc580
--- /dev/null
+++ b/vsrc/SignalToClock.v
@@ -0,0 +1,18 @@
+  
+/* This blackbox is needed by 
+ * Chisel in order to do type conversion.
+ * It may be useful for some synthesis flows
+ * as well which require special 
+ * flagging on conversion from data to clock.
+ */
+
+
+module SignalToClock (
+             output clock_out,
+             input  signal_in
+                      );
+   
+
+  assign clock_out = signal_in;
+                       
+endmodule // SignalToClock