diff --git a/src/db/dbCAC.h b/src/db/dbCAC.h
new file mode 100644
index 000000000..86a1c48e1
--- /dev/null
+++ b/src/db/dbCAC.h
@@ -0,0 +1,112 @@
+
+/*  
+ *  $Id$
+ *
+ *                              
+ *                    L O S  A L A M O S
+ *              Los Alamos National Laboratory
+ *               Los Alamos, New Mexico 87545
+ *                                  
+ *  Copyright, 1986, The Regents of the University of California.
+ *                                  
+ *           
+ *	Author Jeffrey O. Hill
+ *	johill@lanl.gov
+ *	505 665 1831
+ *
+ * NOTES:
+ * 1) This interface is preliminary and will change in the future
+ */
+
+#include "dbNotify.h"
+#include "dbEvent.h"
+#include "dbAddr.h"
+
+extern "C" void putNotifyCompletion ( putNotify *ppn );
+
+class dbPutNotifyIO : public cacNotifyIO {
+public:
+    dbPutNotifyIO ( cacNotify &notify );
+    int initiate ( struct dbAddr &addr, unsigned type, 
+        unsigned long count, const void *pValue);
+    void destroy ();
+    static void * operator new ( size_t size );
+    static void operator delete ( void *pCadaver, size_t size );
+private:
+    putNotify pn;
+    bool ioComplete;
+    static tsFreeList < dbPutNotifyIO > freeList;
+    ~dbPutNotifyIO (); // must allocate out of pool
+    friend void putNotifyCompletion ( putNotify *ppn );
+};
+
+class dbChannelIO;
+
+extern "C" void dbSubscriptionEventCallback ( void *pPrivate, struct dbAddr *paddr,
+	int eventsRemaining, struct db_field_log *pfl );
+
+class dbSubscriptionIO : public cacNotifyIO {
+public:
+    dbSubscriptionIO ( dbChannelIO &chanIO, cacNotify &, unsigned type, unsigned long count );
+    int dbSubscriptionIO::begin ( struct dbAddr &addr, unsigned mask );
+    void destroy ();
+    static void * operator new ( size_t size );
+    static void operator delete ( void *pCadaver, size_t size );
+private:
+    dbChannelIO &chan;
+    dbEventSubscription es;
+    unsigned type;
+    unsigned long count;
+    static tsFreeList < dbSubscriptionIO > freeList;
+    ~dbSubscriptionIO (); // must be allocated from pool
+    friend void dbSubscriptionEventCallback ( void *user_arg, struct dbAddr *paddr,
+	    int eventsRemaining, struct db_field_log *pfl );
+};
+
+class dbServiceIO;
+
+class dbChannelIO : public cacChannelIO {
+public:
+    dbChannelIO (  cacChannel &chan, const dbAddr &addr, dbServiceIO &serviceIO );
+    void destroy ();
+    void subscriptionUpdate ( unsigned type, unsigned long count, 
+            const struct db_field_log *pfl, cacNotifyIO &notify);
+    dbEventSubscription subscribe ( dbSubscriptionIO &subscr, unsigned mask );
+
+    static void * operator new ( size_t size);
+    static void operator delete ( void *pCadaver, size_t size );
+
+private:
+    dbServiceIO &serviceIO;
+    char *pGetCallbackCache;
+    unsigned long getCallbackCacheSize;
+    dbAddr addr;
+
+    static tsFreeList < dbChannelIO > freeList;
+
+    ~dbChannelIO (); // allocate only from pool
+
+    const char *pName () const;
+    int read ( unsigned type, unsigned long count, void *pValue );
+    int read ( unsigned type, unsigned long count, cacNotify & );
+    int write ( unsigned type, unsigned long count, const void *pvalue );
+    int write ( unsigned type, unsigned long count, const void *pvalue, cacNotify & );
+    int subscribe ( unsigned type, unsigned long count, unsigned mask, cacNotify &notify );
+    short nativeType () const;
+    unsigned long nativeElementCount () const;
+};
+
+class dbServiceIO : public cacServiceIO {
+public:
+    dbServiceIO ();
+    ~dbServiceIO ();
+    cacChannelIO *createChannelIO ( cacChannel &chan, const char *pName );
+    void subscriptionUpdate ( struct dbAddr &addr, unsigned type, unsigned long count, 
+            const struct db_field_log *pfl, cacNotifyIO &notify );
+    dbEventSubscription subscribe ( struct dbAddr &addr, dbSubscriptionIO &subscr, unsigned mask );
+private:
+    dbEventCtx ctx;
+    char *pEventCallbackCache;
+    unsigned long eventCallbackCacheSize;
+    osiMutex mutex;
+};
diff --git a/src/db/dbChannelIO.cpp b/src/db/dbChannelIO.cpp
new file mode 100644
index 000000000..5cf7a4d5a
--- /dev/null
+++ b/src/db/dbChannelIO.cpp
@@ -0,0 +1,194 @@
+
+/*  
+ *  $Id$
+ *
+ *                              
+ *                    L O S  A L A M O S
+ *              Los Alamos National Laboratory
+ *               Los Alamos, New Mexico 87545
+ *                                  
+ *  Copyright, 1986, The Regents of the University of California.
+ *                                  
+ *           
+ *	Author Jeffrey O. Hill
+ *	johill@lanl.gov
+ *	505 665 1831
+ */
+
+#include "limits.h"
+
+#include "tsFreeList.h"
+#include "osiMutex.h"
+#include "cadef.h"
+#include "cacIO.h"
+
+#define epicsExportSharedSymbols
+#include "db_access_routines.h"
+#include "dbCAC.h"
+#include "dbLock.h"
+#include "dbCommon.h"
+
+extern "C" unsigned short dbDBRnewToDBRold[DBR_ENUM+1];
+
+tsFreeList < dbChannelIO > dbChannelIO::freeList;
+
+dbChannelIO::dbChannelIO ( cacChannel &chan, const dbAddr &addrIn, dbServiceIO &serviceIO ) :
+    cacChannelIO ( chan ), serviceIO ( serviceIO ), addr ( addrIn ), 
+    pGetCallbackCache ( 0 ), getCallbackCacheSize ( 0ul )
+{
+    this->connectNotify ();
+}
+
+dbChannelIO::~dbChannelIO ()
+{
+    if ( this->pGetCallbackCache ) {
+        delete [] this->pGetCallbackCache;
+    }
+}
+
+void dbChannelIO::destroy () 
+{
+    delete this;
+}
+
+void * dbChannelIO::operator new ( size_t size )
+{
+    return dbChannelIO::freeList.allocate ( size );
+}
+
+void dbChannelIO::operator delete ( void *pCadaver, size_t size )
+{
+    dbChannelIO::freeList.release ( pCadaver, size );
+}
+
+const char *dbChannelIO::pName () const 
+{
+    return addr.precord->name;
+}
+
+int dbChannelIO::read ( unsigned type, unsigned long count, void *pValue )
+{
+    if ( type > INT_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    if ( count > INT_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    int status = db_get_field ( &this->addr, static_cast <int> ( type ), 
+                    pValue, static_cast <int> ( count ), 0);
+    if ( status ) {
+        return ECA_GETFAIL;
+    }
+    else { 
+        return ECA_NORMAL;
+    }
+}
+
+int dbChannelIO::read ( unsigned type, unsigned long count, cacNotify &notify ) 
+{
+    unsigned long size = dbr_size_n ( type, count );
+    if ( type > INT_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    if ( count > INT_MAX ) {
+        return ECA_BADCOUNT;
+    }
+
+    dbScanLock ( this->addr.precord );
+    if ( this->getCallbackCacheSize < size) {
+        if ( this->pGetCallbackCache ) {
+            delete [] this->pGetCallbackCache;
+        }
+        this->pGetCallbackCache = new char [size];
+        if ( ! this->pGetCallbackCache ) {
+            this->getCallbackCacheSize = 0ul;
+            dbScanUnlock ( this->addr.precord );
+            return ECA_ALLOCMEM;
+        }
+        this->getCallbackCacheSize = size;
+    }
+    int status = db_get_field ( &this->addr, static_cast <int> ( type ), 
+                    this->pGetCallbackCache, static_cast <int> ( count ), 0);
+    if ( status ) {
+        notify.exceptionNotify ( ECA_GETFAIL, "db_get_field () completed unsuccessfuly" );
+    }
+    else { 
+        notify.completionNotify ( type, count, this->pGetCallbackCache );
+    }
+    notify.destroy ();
+    dbScanUnlock ( this->addr.precord );
+    return ECA_NORMAL;
+}
+
+int dbChannelIO::write ( unsigned type, unsigned long count, const void *pValue )
+{
+    int status;
+    if ( count > LONG_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    status = db_put_field ( &this->addr, type, pValue, static_cast <long> (count) );
+    if (status) {
+        return ECA_PUTFAIL;
+    }
+    else {
+        return ECA_NORMAL;
+    }
+}
+
+int dbChannelIO::write ( unsigned type, unsigned long count, 
+                        const void *pValue, cacNotify &notify ) 
+{
+    dbPutNotifyIO *pIO;
+    if ( count > LONG_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    pIO = new dbPutNotifyIO ( notify );
+    if ( ! pIO ) {
+        return ECA_ALLOCMEM;
+    }
+    int status = pIO->initiate ( this->addr, type, count, pValue );
+    if ( status != ECA_NORMAL ) {
+        pIO->destroy ();
+    }
+    return status;
+}
+
+int dbChannelIO::subscribe ( unsigned type, unsigned long count, 
+                            unsigned mask, cacNotify &notify ) 
+{
+    dbSubscriptionIO *pIO = new dbSubscriptionIO ( *this, notify, type, count );
+    if ( ! pIO ) {
+        return ECA_ALLOCMEM;
+    }
+    int status = pIO->begin ( this->addr, mask );
+    if ( status != ECA_NORMAL ) {
+        pIO->destroy ();
+    }
+    return status;
+}
+
+short dbChannelIO::nativeType () const 
+{
+    return dbDBRnewToDBRold[this->addr.field_type];
+}
+
+unsigned long dbChannelIO::nativeElementCount () const 
+{
+    if ( this->addr.no_elements >= 0u ) {
+        return static_cast < unsigned long > ( this->addr.no_elements );
+    }
+    else {
+        return 0u;
+    }
+}
+
+void dbChannelIO::subscriptionUpdate ( unsigned type, unsigned long count, 
+        const struct db_field_log *pfl, cacNotifyIO &notify )
+{
+    this->serviceIO.subscriptionUpdate ( this->addr, type, count, pfl, notify );
+}
+
+dbEventSubscription dbChannelIO::subscribe ( dbSubscriptionIO &subscr, unsigned mask )
+{
+    return this->serviceIO.subscribe ( this->addr, subscr, mask );
+}
diff --git a/src/db/dbPutNotifyIO.cpp b/src/db/dbPutNotifyIO.cpp
new file mode 100644
index 000000000..21e3d8e51
--- /dev/null
+++ b/src/db/dbPutNotifyIO.cpp
@@ -0,0 +1,109 @@
+
+/*  
+ *  $Id$
+ *
+ *                              
+ *                    L O S  A L A M O S
+ *              Los Alamos National Laboratory
+ *               Los Alamos, New Mexico 87545
+ *                                  
+ *  Copyright, 1986, The Regents of the University of California.
+ *                                  
+ *           
+ *	Author Jeffrey O. Hill
+ *	johill@lanl.gov
+ *	505 665 1831
+ */
+
+#include "limits.h"
+#include "string.h"
+
+#include "osiMutex.h"
+#include "tsFreeList.h"
+#include "errMdef.h"
+
+#include "cadef.h"
+#include "cacIO.h"
+
+#define epicsExportSharedSymbols
+#include "dbCAC.h"
+
+#define S_db_Blocked 	(M_dbAccess|39)
+#define S_db_Pending 	(M_dbAccess|37)
+
+tsFreeList <dbPutNotifyIO> dbPutNotifyIO::freeList;
+
+extern "C" void putNotifyCompletion ( putNotify *ppn )
+{
+    dbPutNotifyIO *pNotify = static_cast < dbPutNotifyIO * > ( ppn->usrPvt );
+    if ( pNotify->pn.status ) {
+        if (pNotify->pn.status == S_db_Blocked) {
+            pNotify->cacNotifyIO::exceptionNotify ( ECA_PUTCBINPROG, "put notify blocked" );
+        }
+        else {
+            pNotify->cacNotifyIO::exceptionNotify ( ECA_PUTFAIL,  "put notify unsuccessful");
+        }
+    }
+    else {
+        pNotify->cacNotifyIO::completionNotify ();
+    }
+    pNotify->ioComplete = true;
+    pNotify->destroy ();
+}
+
+dbPutNotifyIO::dbPutNotifyIO ( cacNotify &notifyIn ) :
+    cacNotifyIO (notifyIn), ioComplete (false) 
+{
+    memset (&this->pn, '\0', sizeof (this->pn));
+    this->pn.userCallback = putNotifyCompletion;
+    this->pn.usrPvt = this;
+}
+
+dbPutNotifyIO::~dbPutNotifyIO ()
+{
+    if ( ! this->ioComplete ) {
+        dbNotifyCancel ( &this->pn );
+    }
+}
+
+int dbPutNotifyIO::initiate ( struct dbAddr &addr, unsigned type, 
+                             unsigned long count, const void *pValue)
+{
+    int status;
+
+    if ( count > LONG_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    if ( type > SHRT_MAX ) {
+        return ECA_BADTYPE;
+    }
+    this->pn.pbuffer = const_cast <void *> ( pValue );
+    this->pn.nRequest = static_cast <unsigned> ( count );
+    this->pn.paddr = &addr;
+    status = this->pn.dbrType = dbPutNotifyMapType ( &this->pn, static_cast <short> ( type ) );
+    if (status) {
+        return ECA_BADTYPE;
+    }
+
+    status = ::dbPutNotify ( &this->pn );
+    if ( status && status != S_db_Pending ) {
+        this->pn.status = status;
+        putNotifyCallback ();
+    }
+    return ECA_NORMAL;
+}
+
+void dbPutNotifyIO::destroy () 
+{
+    delete this;
+}
+
+void * dbPutNotifyIO::operator new ( size_t size )
+{
+    return dbPutNotifyIO::freeList.allocate ( size );
+}
+
+void dbPutNotifyIO::operator delete ( void *pCadaver, size_t size )
+{
+    dbPutNotifyIO::freeList.release ( pCadaver, size );
+}
diff --git a/src/db/dbServiceIO.cpp b/src/db/dbServiceIO.cpp
new file mode 100644
index 000000000..b1c1087ce
--- /dev/null
+++ b/src/db/dbServiceIO.cpp
@@ -0,0 +1,141 @@
+
+/*  
+ *  $Id$
+ *
+ *                              
+ *                    L O S  A L A M O S
+ *              Los Alamos National Laboratory
+ *               Los Alamos, New Mexico 87545
+ *                                  
+ *  Copyright, 1986, The Regents of the University of California.
+ *                                  
+ *           
+ *	Author Jeffrey O. Hill
+ *	johill@lanl.gov
+ *	505 665 1831
+ */
+
+#include "limits.h"
+
+#include "osiMutex.h"
+#include "tsFreeList.h"
+
+#include "cadef.h"
+#include "cacIO.h"
+
+#define epicsExportSharedSymbols
+#include "db_access_routines.h"
+#include "dbCAC.h"
+
+class loadTimeInit {
+public:
+    loadTimeInit ();
+private:
+    dbServiceIO dbio;
+};
+
+static loadTimeInit lti;
+
+loadTimeInit::loadTimeInit ()
+{
+    cacGlobalServiceList.registerService ( this->dbio );
+}
+
+dbServiceIO::dbServiceIO () :
+    ctx (0), pEventCallbackCache (0), eventCallbackCacheSize (0ul)
+{
+}
+
+dbServiceIO::~dbServiceIO ()
+{
+    if ( this->pEventCallbackCache ) {
+        delete [] this->pEventCallbackCache;
+    }
+    if (this->ctx) {
+        db_close_events (this->ctx);
+    }
+}
+
+cacChannelIO *dbServiceIO::createChannelIO ( cacChannel &chan, const char *pName )
+{
+    struct dbAddr addr;
+
+    int status = db_name_to_addr ( pName, &addr );
+    if (status) {
+        return 0;
+    }
+    else {
+        return new dbChannelIO ( chan, addr, *this ); 
+    }
+}
+
+void dbServiceIO::subscriptionUpdate ( struct dbAddr &addr, unsigned type, unsigned long count, 
+        const struct db_field_log *pfl, cacNotifyIO &notify )
+{
+    unsigned long size = dbr_size_n ( type, count );
+
+    this->mutex.lock ();
+    if ( this->eventCallbackCacheSize < size) {
+        if ( this->pEventCallbackCache ) {
+            delete [] this->pEventCallbackCache;
+        }
+        this->pEventCallbackCache = new char [size];
+        if ( ! this->pEventCallbackCache ) {
+            this->eventCallbackCacheSize = 0ul;
+            this->mutex.unlock ();
+            notify.exceptionNotify ( ECA_ALLOCMEM, "unable to allocate callback cache" );
+            return;
+        }
+        this->eventCallbackCacheSize = size;
+    }
+    void *pvfl = (void *) pfl;
+    int status = db_get_field ( &addr, static_cast <int> ( type ), 
+                    this->pEventCallbackCache, static_cast <int> ( count ), pvfl );
+    if ( status ) {
+        notify.exceptionNotify ( ECA_GETFAIL, "subscription update db_get_field () completed unsuccessfuly" );
+    }
+    else { 
+        notify.completionNotify ( type, count, this->pEventCallbackCache );
+    }
+    this->mutex.unlock ();
+}
+
+extern "C" void cacAttachClientCtx ( void * pPrivate )
+{
+    int status;
+    caClientCtx clientCtx = pPrivate;
+    status = ca_attach_context ( clientCtx );
+    assert ( status == ECA_NORMAL );
+}
+
+dbEventSubscription dbServiceIO::subscribe ( struct dbAddr &addr, dbSubscriptionIO &subscr, unsigned mask )
+{
+    static const int slightlyHigherPriority = -1;
+    int status;
+    caClientCtx clientCtx;
+
+    status = ca_current_context ( &clientCtx );
+    if ( status != ECA_NORMAL ) {
+        return 0;
+    }
+
+    this->mutex.lock ();
+    if ( ! this->ctx ) {
+        this->ctx = db_init_events ();
+        if ( ! this->ctx ) {
+            this->mutex.unlock ();
+            return 0;
+        }
+        status = db_start_events ( this->ctx, "CAC event", 
+            cacAttachClientCtx, clientCtx, slightlyHigherPriority );
+        if ( status ) {
+            db_close_events (this->ctx);
+            this->ctx = 0;
+            return 0;
+        }
+    }
+    this->mutex.unlock ();
+
+    return db_add_event ( this->ctx, &addr,
+        dbSubscriptionEventCallback, (void *) &subscr, mask );
+}
diff --git a/src/db/dbSubscriptionIO.cpp b/src/db/dbSubscriptionIO.cpp
new file mode 100644
index 000000000..d8ca38453
--- /dev/null
+++ b/src/db/dbSubscriptionIO.cpp
@@ -0,0 +1,84 @@
+
+/*  
+ *  $Id$
+ *
+ *                              
+ *                    L O S  A L A M O S
+ *              Los Alamos National Laboratory
+ *               Los Alamos, New Mexico 87545
+ *                                  
+ *  Copyright, 1986, The Regents of the University of California.
+ *                                  
+ *           
+ *	Author Jeffrey O. Hill
+ *	johill@lanl.gov
+ *	505 665 1831
+ */
+
+#include "limits.h"
+
+#include "osiMutex.h"
+#include "tsFreeList.h"
+
+#include "cadef.h"
+#include "cacIO.h"
+
+#define epicsExportSharedSymbols
+#include "dbCAC.h"
+#include "db_access_routines.h"
+
+tsFreeList < dbSubscriptionIO > dbSubscriptionIO::freeList;
+
+dbSubscriptionIO::dbSubscriptionIO ( dbChannelIO &chanIO, 
+    cacNotify &notifyIn, unsigned typeIn, unsigned long countIn ) :
+    cacNotifyIO ( notifyIn ), chan ( chanIO ), es ( 0 ), 
+        type ( typeIn ), count ( countIn )
+{
+}
+
+dbSubscriptionIO::~dbSubscriptionIO ()
+{
+    if ( this->es ) {
+        db_cancel_event ( this->es );
+    }
+}
+
+void dbSubscriptionIO::destroy ()
+{
+    delete this;
+}
+
+void * dbSubscriptionIO::operator new ( size_t size )
+{
+    return dbSubscriptionIO::freeList.allocate ( size );
+}
+
+void dbSubscriptionIO::operator delete ( void *pCadaver, size_t size )
+{
+    dbSubscriptionIO::freeList.release ( pCadaver, size );
+}
+
+extern "C" void dbSubscriptionEventCallback ( void *pPrivate, struct dbAddr *paddr,
+	int eventsRemaining, struct db_field_log *pfl )
+{
+    dbSubscriptionIO *pIO = static_cast <dbSubscriptionIO *> ( pPrivate );
+    pIO->chan.subscriptionUpdate ( pIO->type, pIO->count, pfl, *pIO);
+}
+
+int dbSubscriptionIO::begin ( struct dbAddr &addr, unsigned mask )
+{
+    if ( this->type > INT_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    if ( this->count > INT_MAX ) {
+        return ECA_BADCOUNT;
+    }
+    this->es = this->chan.subscribe ( *this, mask );
+    if ( this->es ) {
+        return ECA_NORMAL;
+    }
+    else {
+        return ECA_ALLOCMEM;
+    }
+}
+