diff --git a/README.md b/README.md
index a2977f8..5a37a51 100644
--- a/README.md
+++ b/README.md
@@ -5,14 +5,15 @@
 hardware registers on POWER Systems chips.
 
 The primary consumers (and requirements drivers) will be:
- * [OpenBMC Hardware Diagnostics](https://github.com/openbmc/openpower-hw-diags)
- * [POWER Systems Hostboot firmware](https://github.com/open-power/hostboot)
+ * [OpenBMC Hardware Diagnostics]
+ * [POWER Systems Hostboot firmware]
  * POWER Systems FSP firmware
 
 Core API
 --------
 
-Details TBD.
+The primary APIs are in the [Isolator class]. See the class definition for
+details on how to use it.
 
 Integration
 -----------
@@ -24,6 +25,7 @@
 
 User Application Requirements and APIs
 --------------------------------------
+
  * The method to access hardware register data will vary per user application.
    Therefore, this library will declare the hardware access [user APIs], but
    each containing user application must implement the APIs for their own
@@ -41,9 +43,6 @@
    header file that defines macros for assertion. Details are included in the
    [user APIs].
 
-[user APIs]: src/hei_user_interface.hpp
-[Chip Data Files]: src/chip_data/CHIP_DATA.md
-
 Environment configuration
 -------------------------
 
@@ -61,5 +60,11 @@
  * Hostboot has a very limited environment. It does not include libc or
    libstdc++. However, Hostboot has implemented select functions from those
    libraries as needed. For details, you can reference `src/include/` in the
-   [Hostboot project](https://github.com/open-power/hostboot).
+   [POWER Systems Hostboot firmware].
+
+[OpenBMC Hardware Diagnostics]: https://github.com/openbmc/openpower-hw-diags
+[POWER Systems Hostboot firmware]: https://github.com/open-power/hostboot
+[Isolator class]: src/hei_isolator.hpp
+[user APIs]: src/hei_user_interface.hpp
+[Chip Data Files]: src/chip_data/CHIP_DATA.md
 
diff --git a/src/chip_data/hei_chip_data.hpp b/src/chip_data/hei_chip_data.hpp
new file mode 100644
index 0000000..810198c
--- /dev/null
+++ b/src/chip_data/hei_chip_data.hpp
@@ -0,0 +1,10 @@
+#pragma once
+
+#include "hei_includes.hpp"
+
+namespace libhei
+{
+
+typedef uint32_t ChipType_t;
+
+} // end namespace libhei
diff --git a/src/hei_includes.hpp b/src/hei_includes.hpp
index fa2506b..dbb8b35 100644
--- a/src/hei_includes.hpp
+++ b/src/hei_includes.hpp
@@ -3,8 +3,12 @@
 // The purpose of this file is to include common headers that will be used
 // throughout this library.
 
+// Standard library includes
 #include <stdint.h>
 
-#include <hei_return_code.hpp>
+// External includes
 #include <hei_user_defines.hpp> // For HEI_ASSERT, HEI_INF, and HEI_ERR
 
+// Internal includes
+#include "hei_return_code.hpp"
+
diff --git a/src/hei_isolation_data.hpp b/src/hei_isolation_data.hpp
new file mode 100644
index 0000000..57344bd
--- /dev/null
+++ b/src/hei_isolation_data.hpp
@@ -0,0 +1,34 @@
+#pragma once
+
+#include "hei_includes.hpp"
+
+namespace libhei
+{
+
+/**
+ * @brief Contain a list of all active hardware errors on a chip, the contents
+ *        of any registers associated with the active errors, and any other data
+ *        that can be useful for debug.
+ */
+class IsolationData
+{
+  public:
+
+    /** @brief Default constructor. */
+    IsolationData() = default;
+
+    /** @brief Copy constructor. */
+    IsolationData( const IsolationData & ) = default;
+
+    /** @brief Assignment operator. */
+    IsolationData & operator=( const IsolationData & ) = default;
+
+    /** @brief Destructor. */
+    ~IsolationData() = default;
+
+  private:
+
+}; // end class IsolationData
+
+} // end namespace libhei
+
diff --git a/src/hei_isolator.cpp b/src/hei_isolator.cpp
index fda761f..6a81707 100644
--- a/src/hei_isolator.cpp
+++ b/src/hei_isolator.cpp
@@ -4,24 +4,30 @@
 namespace libhei
 {
 
-Isolator::Isolator()
+ReturnCode Isolator::initialize( void * i_buffer, size_t i_bufferSize,
+                                 bool i_forceInit )
 {
-    HEI_INF( "Isolator::Isolator()" );
+    ReturnCode rc;
+
+    // BEGIN temporary code for compilation
+    HEI_INF( "Isolator::initialize(%p,%lu,%d)", i_buffer, i_bufferSize,
+             i_forceInit );
+    // END temporary code for compilation
+
+    return rc;
 }
 
-Isolator::~Isolator()
+ReturnCode Isolator::isolate( void * i_chip, ChipType_t i_chipType,
+                              IsolationData & o_isoData )
 {
-    HEI_INF( "Isolator::~Isolator()" );
-}
+    ReturnCode rc;
 
-void Isolator::initialize()
-{
-    HEI_INF( "Isolator::initialize()" );
-}
+    // BEGIN temporary code for compilation
+    o_isoData = IsolationData();
+    HEI_INF( "Isolator::isolate(%p,%u)", i_chip, i_chipType );
+    // END temporary code for compilation
 
-void Isolator::isolate()
-{
-    HEI_INF( "Isolator::isolate()" );
+    return rc;
 }
 
 } // end namespace libhei
diff --git a/src/hei_isolator.hpp b/src/hei_isolator.hpp
index 483b260..3a07d75 100644
--- a/src/hei_isolator.hpp
+++ b/src/hei_isolator.hpp
@@ -1,22 +1,113 @@
-
 #pragma once
 
-#include "hei_user_interface.hpp"
+#include "hei_includes.hpp"
+#include "hei_isolation_data.hpp"
+#include "chip_data/hei_chip_data.hpp"
 
 namespace libhei
 {
 
+/**
+ * @brief This is the main API for Hardware Error Isolation (aka the isolator).
+ *
+ * The intended flow is to:
+ *  - Create a singleton instance of an Isolator object.
+ *  - Use initialize() to input each necessary Chip Data File (provided by the
+ *    user application).
+ *  - Call isolate() each time you want to find all active errors being
+ *    reported by a chip.
+ *  - Once isolation is no longer needed, the Isolator singleton can be deleted
+ *    to free up internal resources.
+ *
+ * The purpose of the singleton instance is to avoid initializing the object
+ * each time isolation is required. The data provided by the Chip Data Files is
+ * static. So reinitializing would be a waste of time, unless for some reason
+ * the Chip Data Files themselves are updated, which would require
+ * reinitialization anyway. Of course, leaving the object in memory chews up
+ * resources. So, some users may need to weigh performance vs. memory usage.
+ */
 class Isolator
 {
   public:
 
-    Isolator();
+    /** @brief Default constructor. */
+    Isolator() = default;
 
-    ~Isolator();
+    /** @brief Destructor. */
+    ~Isolator() = default;
 
-    void initialize();
+    /** @brief Copy constructor. */
+    Isolator( const Isolator & ) = delete;
 
-    void isolate();
+    /** @brief Assignment operator. */
+    Isolator & operator=( const Isolator & ) = delete;
+
+    /**
+     * @brief Initializes internal isolation objects based on data from the
+     *        given Chip Data File.
+     *
+     * This function only takes one Chip Data File at a time. Therefore, the
+     * user application must call this function for each Chip Data File required
+     * for isolation.
+     *
+     * Storage and management of the Chip Data Files will vary per user
+     * application. Therefore, the user application is responsible for loading
+     * the Chip Data Files into memory, as needed, and providing the location
+     * and size of the data.
+     *
+     * Once initialization has successfully completed with a Chip Data File, the
+     * file is no longer needed in memory.
+     *
+     * Details of the Chip Data File format can be found in CHIP_DATA.md.
+     *
+     * @param i_buffer     A pointer to the buffer containing a single Chip
+     *                     Data File.
+     *
+     * @param i_bufferSize The size (in bytes) of the target Chip Data File.
+     *
+     * @param i_forceInit  It is possible the user application could call this
+     *                     function for a chip type that has already been
+     *                     initialized. This is useful if for some reason the
+     *                     Chip Data File is for a chip type has been updated.
+     *                     If this function is called and a chip type has
+     *                     already been initialized:
+     *                      - false (default), the function will return
+     *                        RC_CDF_INITIALIZED and exit.
+     *                      - true, the function will delete previous isolation
+     *                        objects for this chip type and reinitialize.
+     *
+     * @return RC_SUCCESS or RC_CDF_INVALID or RC_CDF_INITIALIZED
+     */
+    ReturnCode initialize( void * i_buffer, size_t i_bufferSize,
+                           bool i_forceInit = false );
+
+    /**
+     * @brief Isolates all active hardware errors found on the given chip.
+     *
+     * This functions requires initialize() to be called with the Chip Data File
+     * corresponding to the given chip type.
+     *
+     * @param i_chip     This is simply a pointer to a user application object
+     *                   that represents the target chip. The isolator does not
+     *                   know anything about this object or how to use it. This
+     *                   parameter's only purpose is to eventually get passed
+     *                   back to the user application in a deviceRead()
+     *                   operation.
+     *
+     * @param i_chipType Each Chip Data File contains a unique chip type
+     *                   identifier. The user application will need to input
+     *                   this value so the isolator will know which set of the
+     *                   isolation objects to reference.
+     *
+     * @param o_isoData  This return object will contain a list of all active
+     *                   hardware errors on this chip, the contents of any
+     *                   registers associated with the active errors, and any
+     *                   other data that can be useful for debug.
+     *
+     * @return RC_SUCCESS or RC_CHIP_DATA_MISSING
+     */
+    ReturnCode isolate( void * i_chip, ChipType_t i_chipType,
+                        IsolationData & o_isoData );
 
   private:
 
diff --git a/src/hei_return_code.hpp b/src/hei_return_code.hpp
index cdb1700..ce32468 100644
--- a/src/hei_return_code.hpp
+++ b/src/hei_return_code.hpp
@@ -59,7 +59,17 @@
 };
 
 /** Function returned successfully. */
-static constexpr ReturnCode RC_SUCCESS = ReturnCode();
+static constexpr ReturnCode RC_SUCCESS                 = ReturnCode();
 
-}; // end namespace libhei
+/** The given Chip Data File is malformed or unsupported. */
+static constexpr ReturnCode RC_CHIP_DATA_INVALID       = ReturnCode(0x00000001);
+
+/** The given Chip Data File contains a chip type that has already been
+ *  initialized. */
+static constexpr ReturnCode RC_CHIP_DATA_INITIALIZED   = ReturnCode(0x00000002);
+
+/** The given chip type has not been initialized. */
+static constexpr ReturnCode RC_CHIP_DATA_MISSING       = ReturnCode(0x00000003);
+
+} // end namespace libhei
 
diff --git a/src/hei_user_interface.hpp b/src/hei_user_interface.hpp
index 30e869d..1d3b5d3 100644
--- a/src/hei_user_interface.hpp
+++ b/src/hei_user_interface.hpp
@@ -1,4 +1,3 @@
-
 #pragma once
 
 // The user application must define this header file with the following macros:
@@ -16,16 +15,26 @@
 {
 
 /**
- *  @brief Perform a hardware read operation.
+ * @brief Perform a hardware read operation.
+ * @param i_chip This is a pointer to a user application object that represents
+ *               the target chip. The isolator does not know anything about this
+ *               object or how to use it. It is provide by the user application
+ *               via the Isolator APIs. The user application is responsible for
+ *               knowing what to do with this parameter.
  */
-void deviceRead();
+ReturnCode deviceRead( void * i_chip );
 
 #ifndef __HEI_READ_ONLY
 
 /**
- *  @brief Perform a hardware write operation.
+ * @brief Perform a hardware write operation.
+ * @param i_chip This is a pointer to a user application object that represents
+ *               the target chip. The isolator does not know anything about this
+ *               object or how to use it. It is provide by the user application
+ *               via the Isolator APIs. The user application is responsible for
+ *               knowing what to do with this parameter.
  */
-void deviceWrite();
+ReturnCode deviceWrite( void * i_chip );
 
 #endif
 
diff --git a/test/simulator/hei_sim_main.cpp b/test/simulator/hei_sim_main.cpp
index 41ffe7f..e83a577 100644
--- a/test/simulator/hei_sim_main.cpp
+++ b/test/simulator/hei_sim_main.cpp
@@ -4,9 +4,16 @@
 {
     libhei::Isolator iso;
 
-    iso.initialize();
+    void * buffer = nullptr;
+    size_t sz_buffer = 0;
 
-    iso.isolate();
+    iso.initialize( buffer, sz_buffer );
+
+    void * chip = nullptr;
+    libhei::ChipType_t chipType = 0;
+    libhei::IsolationData isoData;
+
+    iso.isolate( chip, chipType, isoData );
 
     return 0;
 }