diff --git a/libopenfpga/libarchopenfpga/arch/sample_arch.xml b/libopenfpga/libarchopenfpga/arch/sample_arch.xml
index 9a7f87ff3..5008fcbe9 100644
--- a/libopenfpga/libarchopenfpga/arch/sample_arch.xml
+++ b/libopenfpga/libarchopenfpga/arch/sample_arch.xml
@@ -16,6 +16,7 @@
       <io_nmos model_name="nch_25" chan_length="270e-9" min_width="320e-9"/>
       <io_pmos model_name="pch_25" chan_length="270e-9" min_width="320e-9"/>
     </transistors>
+    <rram model_name="rram" rlrs="5e3" rhrs="20e6"/> 
   </technology>
   <circuit_library>
     <circuit_model type="inv_buf" name="INVTX1" prefix="INVTX1" is_default="true">
diff --git a/libopenfpga/libarchopenfpga/src/circuit_library.cpp b/libopenfpga/libarchopenfpga/src/circuit_library.cpp
index 4b02ca198..a94b4b8a2 100644
--- a/libopenfpga/libarchopenfpga/src/circuit_library.cpp
+++ b/libopenfpga/libarchopenfpga/src/circuit_library.cpp
@@ -886,7 +886,7 @@ size_t CircuitLibrary::port_lut_frac_level(const CircuitPortId& circuit_port_id)
 }
 
 /* Return indices of internal nodes in a LUT multiplexing structure to which the output port is wired to */
-std::vector<size_t> CircuitLibrary::port_lut_output_masks(const CircuitPortId& circuit_port_id) const {
+std::vector<size_t> CircuitLibrary::port_lut_output_mask(const CircuitPortId& circuit_port_id) const {
   /* validate the circuit_port_id */
   VTR_ASSERT(valid_circuit_port_id(circuit_port_id));
   return port_lut_output_masks_[circuit_port_id];
@@ -927,6 +927,13 @@ std::string CircuitLibrary::model_name(const CircuitPortId& port_id) const {
   return model_names_[port_parent_model(port_id)];
 }
 
+/* Return the name of inverter circuit model linked to a circuit port */
+std::string CircuitLibrary::port_inv_model_name(const CircuitPortId& circuit_port_id) const {
+  /* validate the circuit_port_id */
+  VTR_ASSERT(valid_circuit_port_id(circuit_port_id));
+  return port_inv_model_names_[circuit_port_id];
+}
+
 /************************************************************************
  * Public Accessors : Methods to visit timing graphs 
  ***********************************************************************/
diff --git a/libopenfpga/libarchopenfpga/src/circuit_library.h b/libopenfpga/libarchopenfpga/src/circuit_library.h
index 021be9b7a..4150ceebf 100644
--- a/libopenfpga/libarchopenfpga/src/circuit_library.h
+++ b/libopenfpga/libarchopenfpga/src/circuit_library.h
@@ -265,12 +265,13 @@ class CircuitLibrary {
     bool port_is_config_enable(const CircuitPortId& circuit_port_id) const;
     bool port_is_prog(const CircuitPortId& circuit_port_id) const;
     size_t port_lut_frac_level(const CircuitPortId& circuit_port_id) const;
-    std::vector<size_t> port_lut_output_masks(const CircuitPortId& circuit_port_id) const;
+    std::vector<size_t> port_lut_output_mask(const CircuitPortId& circuit_port_id) const;
     std::string port_tri_state_map(const CircuitPortId& circuit_port_id) const;
     CircuitModelId port_tri_state_model(const CircuitPortId& circuit_port_id) const;
     std::string port_tri_state_model_name(const CircuitPortId& circuit_port_id) const;
     CircuitModelId port_parent_model(const CircuitPortId& circuit_port_id) const;
     std::string model_name(const CircuitPortId& port_id) const;
+    std::string port_inv_model_name(const CircuitPortId& circuit_port_id) const;
   public: /* Public Accessors: Timing graph */
     /* Get source/sink nodes and delay of edges */
     std::vector<CircuitEdgeId> timing_edges_by_model(const CircuitModelId& model_id) const;
diff --git a/libopenfpga/libarchopenfpga/src/read_xml_circuit_library.cpp b/libopenfpga/libarchopenfpga/src/read_xml_circuit_library.cpp
index b5a514bfb..b4cce468c 100644
--- a/libopenfpga/libarchopenfpga/src/read_xml_circuit_library.cpp
+++ b/libopenfpga/libarchopenfpga/src/read_xml_circuit_library.cpp
@@ -426,9 +426,9 @@ static
 void read_xml_output_mask(pugi::xml_node& xml_port,
                           const pugiutil::loc_data& loc_data,
                           CircuitLibrary& circuit_lib, const CircuitPortId& port) {
-  const char* output_mask_attr = get_attribute(xml_port, "lut_output_mask", loc_data, pugiutil::ReqOpt::OPTIONAL).value();
+  std::string output_mask_attr = get_attribute(xml_port, "lut_output_mask", loc_data, pugiutil::ReqOpt::OPTIONAL).as_string();
   std::vector<size_t> mask_vector;
-  if (nullptr != output_mask_attr) {
+  if (!output_mask_attr.empty()) {
     /* Split the string with token ',' */
     openfpga::StringToken string_tokenizer(get_attribute(xml_port, "lut_output_mask", loc_data, pugiutil::ReqOpt::OPTIONAL).as_string(nullptr));
     for (const std::string& mask_token : string_tokenizer.split(',')) {
@@ -722,9 +722,12 @@ void read_xml_circuit_model(pugi::xml_node& xml_model,
    * We count the number of ports in total and then add one by one 
    */
   size_t num_ports = count_children(xml_model, "port", loc_data, pugiutil::ReqOpt::OPTIONAL);
-  for (size_t iport = 0; iport < num_ports; ++iport) {
-    auto xml_port = get_first_child(xml_model, "port", loc_data);
-    read_xml_circuit_port(xml_port, loc_data, circuit_lib, model);
+  if (0 < num_ports) {
+    pugi::xml_node xml_port = get_first_child(xml_model, "port", loc_data);
+    while (xml_port) {
+      read_xml_circuit_port(xml_port, loc_data, circuit_lib, model);
+      xml_port = xml_port.next_sibling(xml_port.name());
+    } 
   }
 
   /* Parse the parasitics of wires */
@@ -736,9 +739,12 @@ void read_xml_circuit_model(pugi::xml_node& xml_model,
 
   /* Parse all the delay matrix if defined */
   size_t num_delay_matrix = count_children(xml_model, "delay_matrix", loc_data, pugiutil::ReqOpt::OPTIONAL);
-  for (size_t idelay_matrix = 0; idelay_matrix < num_delay_matrix; ++idelay_matrix) {
-    auto xml_delay_matrix = get_first_child(xml_model, "delay_matrix", loc_data);
-    read_xml_delay_matrix(xml_delay_matrix, loc_data, circuit_lib, model);
+  if (0 < num_delay_matrix) {
+    pugi::xml_node xml_delay_matrix = get_first_child(xml_model, "delay_matrix", loc_data);
+    while (xml_delay_matrix) {
+      read_xml_delay_matrix(xml_delay_matrix, loc_data, circuit_lib, model);
+      xml_delay_matrix = xml_delay_matrix.next_sibling(xml_delay_matrix.name());
+    }
   }
 }
 
diff --git a/libopenfpga/libarchopenfpga/src/write_xml_circuit_library.cpp b/libopenfpga/libarchopenfpga/src/write_xml_circuit_library.cpp
index 146fe381d..60acf66d9 100644
--- a/libopenfpga/libarchopenfpga/src/write_xml_circuit_library.cpp
+++ b/libopenfpga/libarchopenfpga/src/write_xml_circuit_library.cpp
@@ -89,7 +89,123 @@ void write_xml_design_technology(std::fstream& fp,
 
   /* Finish all the attributes, we can return here */
   fp << "/>" << "\n";
-  return;
+}
+
+/********************************************************************
+ * A writer to output a circuit port to XML format
+ *******************************************************************/
+static 
+void write_xml_circuit_port(std::fstream& fp,
+                            const char* fname,
+                            const CircuitLibrary& circuit_lib,
+                            const CircuitPortId& port) {
+  /* Validate the file stream */
+  openfpga::check_file_stream(fname, fp);
+
+  /* Get the parent circuit model for this port */
+  const CircuitModelId& model = circuit_lib.port_parent_model(port);
+
+  /* Generic information about a port */
+  fp << "\t\t\t" << "<port";
+  write_xml_attribute(fp, "type", CIRCUIT_MODEL_PORT_TYPE_STRING[circuit_lib.port_type(port)]); 
+  write_xml_attribute(fp, "prefix", circuit_lib.port_prefix(port).c_str()); 
+ 
+  /* Output the lib_name when it is different than prefix */
+  if (circuit_lib.port_prefix(port) != circuit_lib.port_lib_name(port)) {
+    write_xml_attribute(fp, "lib_name", circuit_lib.port_lib_name(port).c_str()); 
+  } 
+
+  write_xml_attribute(fp, "size", std::to_string(circuit_lib.port_size(port)).c_str()); 
+
+  /* Output the default value only when this is a global port */
+  if (true == circuit_lib.port_is_global(port)) {
+    write_xml_attribute(fp, "default_val", std::to_string(circuit_lib.port_default_value(port)).c_str()); 
+  }
+
+  /* SRAM port may be for mode selection. Output it only when it is true */
+  if (CIRCUIT_MODEL_PORT_SRAM == circuit_lib.port_type(port)) {
+    if (true == circuit_lib.port_is_mode_select(port)) {
+      write_xml_attribute(fp, "mode_select", "true"); 
+    }
+  }
+
+  /* Output the tri-state map of the port 
+   * This is only applicable to input ports of a LUT
+   */
+  if ( (CIRCUIT_MODEL_LUT == circuit_lib.model_type(model))
+    && (CIRCUIT_MODEL_PORT_INPUT == circuit_lib.port_type(port)) ) {
+    if (!circuit_lib.port_tri_state_map(port).empty()) {
+      write_xml_attribute(fp, "tri_state_map", circuit_lib.port_tri_state_map(port).c_str()); 
+    }
+  }
+
+  /* Identify the fracturable-level of the port in LUTs, by default it will be -1
+   * This is only applicable to output ports of a LUT
+   */
+  if ( (CIRCUIT_MODEL_LUT == circuit_lib.model_type(model))
+    && (CIRCUIT_MODEL_PORT_OUTPUT == circuit_lib.port_type(port)) ) {
+    if (size_t(-1) != circuit_lib.port_lut_frac_level(port)) {
+      write_xml_attribute(fp, "lut_frac_level", std::to_string(circuit_lib.port_lut_frac_level(port)).c_str()); 
+    }
+  }
+
+  /* Output the output mask of the port 
+   * This is only applicable to output ports of a LUT
+   */
+  if ( (CIRCUIT_MODEL_LUT == circuit_lib.model_type(model))
+    && (CIRCUIT_MODEL_PORT_OUTPUT == circuit_lib.port_type(port)) ) {
+    std::string output_mask_string;
+    for (const size_t& mask : circuit_lib.port_lut_output_mask(port)) {
+      if (!output_mask_string.empty()) {
+        output_mask_string += std::string(",");
+      }
+      output_mask_string += std::to_string(mask);
+    }
+    if (!output_mask_string.empty()) {
+      write_xml_attribute(fp, "lut_output_mask", output_mask_string.c_str()); 
+    }
+  }
+
+  /* Global, reset, set port attributes */
+  if (true == circuit_lib.port_is_global(port)) {
+    write_xml_attribute(fp, "is_global", "true"); 
+  }
+
+  if (true == circuit_lib.port_is_reset(port)) {
+    write_xml_attribute(fp, "is_reset", "true"); 
+  }
+
+  if (true == circuit_lib.port_is_set(port)) {
+    write_xml_attribute(fp, "is_set", "true"); 
+  }
+
+  if (true == circuit_lib.port_is_prog(port)) {
+    write_xml_attribute(fp, "is_prog", "true"); 
+  }
+
+  if (true == circuit_lib.port_is_config_enable(port)) {
+    write_xml_attribute(fp, "is_config_enable", "true"); 
+  }
+
+  /* Output the name of circuit model that this port is linked to */
+  if (!circuit_lib.port_tri_state_model_name(port).empty()) {
+    write_xml_attribute(fp, "circuit_model_name", circuit_lib.port_tri_state_model_name(port).c_str());
+  }
+
+  /* Find the name of circuit model that port is used for inversion of signals,
+   * This is only applicable to BL/WL/BLB/WLB ports
+   */
+  if (  (CIRCUIT_MODEL_PORT_BL  == circuit_lib.port_type(port))
+     || (CIRCUIT_MODEL_PORT_WL  == circuit_lib.port_type(port))
+     || (CIRCUIT_MODEL_PORT_BLB == circuit_lib.port_type(port))
+     || (CIRCUIT_MODEL_PORT_WLB == circuit_lib.port_type(port)) ) {
+    if (!circuit_lib.port_inv_model_name(port).empty()) {
+      write_xml_attribute(fp, "inv_circuit_model_name", circuit_lib.port_inv_model_name(port).c_str());
+    }
+  }
+
+  /* Finish all the attributes, we can return here */
+  fp << "/>" << "\n";
 }
 
 /********************************************************************
@@ -125,7 +241,18 @@ void write_xml_circuit_model(std::fstream& fp,
   /* Write the design technology of circuit model */
   write_xml_design_technology(fp, fname, circuit_lib, model);
 
-  /* TODO: Write the ports of circuit model */
+  /* TODO: Write the input buffer information of circuit model */
+  /* TODO: Write the output buffer information of circuit model */
+  /* TODO: Write the lut input buffer information of circuit model */
+  /* TODO: Write the lut input inverter information of circuit model */
+  /* TODO: Write the lut intermediate buffer information of circuit model */
+
+  /* TODO: Write the pass-gate-logic information of circuit model */
+
+  /* Write the ports of circuit model */
+  for (const CircuitPortId& port : circuit_lib.model_ports(model)) {
+    write_xml_circuit_port(fp, fname, circuit_lib, port);
+  }
 
   /* TODO: Write the wire parasticis of circuit model */