diff --git a/README.md b/README.md
index 190f45427..3cb4b740b 100644
--- a/README.md
+++ b/README.md
@@ -10,13 +10,93 @@ Corundum is an open source, high performance FPGA based NIC.
 
 ### Modules
 
-### Common signals
+#### cpl_queue_manager module
 
-### Common parameters
+Completion queue manager module.  Stores device to host queue state in block
+RAM or ultra RAM.
+
+#### event_mux module
+
+Event mux module.  Enables multiple event sources to feed the same event queue.
+
+#### event_queue module
+
+Event queue module.  Responsible for writing event queue entries into host
+memory.
+
+#### interface module
+
+Interface module.  Contains the event queues, interface queues, and ports.
+
+#### port module
+
+Port module.  Contains the transmit and receive engines
+
+#### queue_manager module
+
+Queue manager module.  Stores host to device queue state in block RAM or ultra
+RAM.
+
+#### rx_checksum module
+
+Receive checksum computation module.  Computes 16 bit checksum of Ethernet
+frame payload to aid in IP checksum offloading.
+
+#### rx_engine module
+
+Receive engine.  Manages receive descriptor dequeue and fetch via DMA, packet
+reception, data writeback via DMA, and completion enqueue and writeback via
+DMA.  Handles PTP timestamps for inclusion in completion records.
+
+#### tdma_ber_ch module
+
+TDMA bit error ratio test channel module.  Controls PRBS logic in Ethernet PHY
+and accumulates bit errors.  Can be configured to bin error counts by TDMA
+timeslot.
+
+#### tdma_ber module
+
+TDMA bit error ratio test module.  Wrapper for a tdma_scheduler and multiple
+instances of tdma_ber_ch.
+
+#### tdma_scheduler module
+
+TDMA scheduler module.  Generates TDMA timeslot index and timing signals from
+PTP time.
+
+#### tx_engine module
+
+Transmit engine.  Manages receive descriptor dequeue and fetch via DMA, packet
+data fetch via DMA, packet transmission, and completion enqueue and writeback
+via DMA.  Handles PTP timestamps for inclusion in completion records.
+
+#### tx_scheduler_rr module
+
+Round-robin transmit scheduler.  Determines which queues from which to send
+packets.
+
+#### tx_scheduler_tdma_rr module
+
+Round-robin TDMA transmit scheduler.  Determines which queues from which to
+send packets.  Contains a tdma_scheduler instance to control configuration
+based on PTP time.
 
 ### Source Files
 
-    arbiter.v               : Parametrizable arbiter
+    cpl_queue_manager.v      : Completion queue manager
+    event_mux.v              : Event mux
+    event_queue.v            : Event queue
+    interface.v              : Interface
+    port.v                   : Port
+    queue_manager.v          : Queue manager
+    rx_checksum.v            : Receive checksum offload
+    rx_engine.v              : Receive engine
+    tdma_ber_ch.v            : TDMA BER channel
+    tdma_ber.v               : TDMA BER
+    tdma_scheduler.v         : TDMA scheduler
+    tx_engine.v              : Transmit engine
+    tx_scheduler_rr.v        : Round robin transmit scheduler
+    tx_scheduler_tdma_rr.v   : Round robin TDMA transmit scheduler
 
 ## Testing
 
@@ -27,6 +107,15 @@ individual test scripts can be run with python directly.
 
 ### Testbench Files
 
+    tb/axi.py            : MyHDL AXI4 master and memory BFM
+    tb/axil.py           : MyHDL AXI4 lite master and memory BFM
     tb/axis_ep.py        : MyHDL AXI Stream endpoints
+    tb/eth_ep.py         : MyHDL Ethernet frame endpoints
+    tb/ip_ep.py          : MyHDL IP frame endpoints
+    tb/mqnic.py          : MyHDL mqnic driver model
     tb/pcie.py           : MyHDL PCI Express BFM
     tb/pcie_us.py        : MyHDL Xilinx Ultrascale PCIe core model
+    tb/pcie_usp.py       : MyHDL Xilinx Ultrascale Plus PCIe core model
+    tb/ptp.py            : MyHDL PTP clock model
+    tb/udp_ep.py         : MyHDL UDP frame endpoints
+    tb/xgmii_ep.py       : MyHDL XGMII endpoints