diff --git a/Makefile b/Makefile
index a642f6d4..7b9631a5 100644
--- a/Makefile
+++ b/Makefile
@@ -9,18 +9,23 @@ TOP_DIR:=$(abspath $(dir $(lastword $(MAKEFILE_LIST))))
 # RELEASE = lastest pulls the latest V3.0.0 branch version as at the issue of this make
 # otherwise it pulls the labelled version in the SDK version's release directory
 #
-ifeq ("$(RELEASE)","latest")
-  export RELEASE:=$(RELEASE)
-  SDK_VER        := 3.0.0-dev-190412
-  SDK_COMMIT_SHA1:= 39ec2d4573eb77fda73f6afcf6dd1b3c41e74fcd
-  SDK_FILE_SHA1  := 44f7724490739536526fc4298d6fcc2fa2d29471
-  SDK_ZIP_ROOT   := ESP8266_NONOS_SDK-$(SDK_COMMIT_SHA1)
-  SDK_FILE_VER   := $(SDK_COMMIT_SHA1)
-else
-  SDK_VER        := 3.0
-  SDK_FILE_SHA1  := 029fc23fe87e03c9852de636490b2d7b9e07f01a
+ifeq ("$(RELEASE)","latest-3.0")
+  SDK_VER        := 3.0.0
+  SDK_FILE_SHA1  := NA
+  SDK_ZIP_ROOT   := ESP8266_NONOS_SDK-release-v$(SDK_VER)
+  SDK_FILE_VER   := release/v$(SDK_VER)
+else ifeq ("$(RELEASE)","master")
+  SDK_VER        := master
+  SDK_FILE_SHA1  := NA
   SDK_ZIP_ROOT   := ESP8266_NONOS_SDK-$(SDK_VER)
-  SDK_FILE_VER   := v$(SDK_VER)
+  SDK_FILE_VER   := $(SDK_VER)
+else
+# SDK_VER        := 3.0
+# SDK_FILE_VER   := v$(SDK_VER)
+  SDK_FILE_VER   := e4434aa730e78c63040ace360493aef420ec267c
+  SDK_VER        := 3.0-e4434aa
+  SDK_FILE_SHA1  := ac6528a6a206d3d4c220e4035ced423eb314cfbf
+  SDK_ZIP_ROOT   := ESP8266_NONOS_SDK-$(SDK_FILE_VER)
 endif
 SDK_REL_DIR      := sdk/esp_iot_sdk_v$(SDK_VER)
 SDK_DIR          := $(TOP_DIR)/$(SDK_REL_DIR)
@@ -314,10 +319,10 @@ $(TOP_DIR)/sdk/.extracted-$(SDK_VER): $(TOP_DIR)/cache/$(SDK_FILE_VER).zip
 	(cd "$(dir $@)" && \
 	 rm -fr esp_iot_sdk_v$(SDK_VER) ESP8266_NONOS_SDK-* && \
 	 unzip $(TOP_DIR)/cache/$(SDK_FILE_VER).zip \
-	       '$(SDK_ZIP_ROOT)/lib/*' \
-	       '$(SDK_ZIP_ROOT)/ld/*.v6.ld' \
-	       '$(SDK_ZIP_ROOT)/include/*' \
-	       '$(SDK_ZIP_ROOT)/bin/esp_init_data_default_v05.bin' \
+	       '*/lib/*' \
+	       '*/ld/*.v6.ld' \
+	       '*/include/*' \
+	       '*/bin/esp_init_data_default_v05.bin' \
 	)
 	mv $(dir $@)/$(SDK_ZIP_ROOT) $(dir $@)/esp_iot_sdk_v$(SDK_VER)
 	touch $@
@@ -334,7 +339,7 @@ $(TOP_DIR)/cache/$(SDK_FILE_VER).zip:
 	mkdir -p "$(dir $@)"
 	$(summary) WGET $(patsubst $(TOP_DIR)/%,%,$@)
 	$(WGET) $(GITHUB_SDK)/archive/$(SDK_FILE_VER).zip -O $@ || { rm -f "$@"; exit 1; }
-	(echo "$(SDK_FILE_SHA1)  $@" | sha1sum -c -) || { rm -f "$@"; exit 1; }
+	if test "$(SDK_FILE_SHA1)" != "NA"; then echo "$(SDK_FILE_SHA1)  $@" | sha1sum -c - || { rm -f "$@"; exit 1; }; fi
 
 clean:
 	$(foreach d, $(SUBDIRS), $(MAKE) -C $(d) clean;)
diff --git a/app/Makefile b/app/Makefile
index e4aa96c2..52c57da5 100644
--- a/app/Makefile
+++ b/app/Makefile
@@ -143,6 +143,7 @@ CONFIGURATION_DEFINES =	-D__ets__ 		\
 			-DEBUF_LWIP		\
 			-DUSE_OPTIMIZE_PRINTF	\
 			-DMBEDTLS_USER_CONFIG_FILE=\"user_mbedtls.h\"  \
+			-DMEM_DEFAULT_USE_DRAM
 
 DEFINES += 					\
 	$(UNIVERSAL_TARGET_DEFINES) 		\
diff --git a/app/esp-gdbstub/gdbstub.c b/app/esp-gdbstub/gdbstub.c
index 509e9bb4..9849b5c4 100644
--- a/app/esp-gdbstub/gdbstub.c
+++ b/app/esp-gdbstub/gdbstub.c
@@ -107,7 +107,7 @@ extern void xthal_set_intenable(int);
 #define OBUFLEN 32
 
 //The asm stub saves the Xtensa registers here when a debugging exception happens.
-struct XTensa_exception_frame_s gdbstub_savedRegs;
+struct XTensa_exception_frame_s IRAM_DATA_ATTR gdbstub_savedRegs;
 #if GDBSTUB_USE_OWN_STACK
 //This is the debugging exception stack.
 int exceptionStack[256];
diff --git a/app/include/user_config.h b/app/include/user_config.h
index 49f79c86..64870bb2 100644
--- a/app/include/user_config.h
+++ b/app/include/user_config.h
@@ -278,6 +278,8 @@ extern void luaL_dbgbreak(void);
 #define ICACHE_FLASH_RESERVED_ATTR \
   __attribute__((section(".irom.reserved." __FILE__ "." ICACHE_STRING(__LINE__)),\
                  used,unused,aligned(INTERNAL_FLASH_SECTOR_SIZE)))
+#define IRAM_DATA_ATTR \
+  __attribute__((section(".iram0.data." __FILE__ "." ICACHE_STRING(__LINE__))))
 
 #ifdef  GPIO_SAFE_NO_INTR_ENABLE
 #define NO_INTR_CODE ICACHE_RAM_ATTR __attribute__ ((noinline))
diff --git a/app/lua/lauxlib.c b/app/lua/lauxlib.c
index de2ae489..514b75e3 100644
--- a/app/lua/lauxlib.c
+++ b/app/lua/lauxlib.c
@@ -918,6 +918,11 @@ static int l_check_memlimit(lua_State *L, size_t needbytes) {
   return (g->totalbytes >= limit) ? 1 : 0;
 }
 
+#ifndef LUA_CROSS_COMPILER
+#define REALLOC(p,o,n) (void *) this_realloc(p,o,n)
+#else
+#define REALLOC(p,o,n) (void *) (ptr? this_realloc(p,o,n) : c_malloc(n))
+#endif
 
 static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
   lua_State *L = (lua_State *)ud;
@@ -946,10 +951,11 @@ static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
     if(G(L)->memlimit > 0 && (mode & EGC_ON_MEM_LIMIT) && l_check_memlimit(L, nsize - osize))
       return NULL;
   }
-  nptr = (void *)this_realloc(ptr, osize, nsize);
+  nptr = REALLOC(ptr, osize, nsize);
   if (nptr == NULL && L != NULL && (mode & EGC_ON_ALLOC_FAILURE)) {
+    dbg_printf("Emergency full collection\n");  /**** DEBUG ***/
     luaC_fullgc(L); /* emergency full collection. */
-    nptr = (void *)this_realloc(ptr, osize, nsize); /* try allocation again */
+    nptr = REALLOC(ptr, osize, nsize); /* try allocation again */
   }
   return nptr;
 }
diff --git a/app/lua/lrotable.c b/app/lua/lrotable.c
index 80230db8..d4290ae1 100644
--- a/app/lua/lrotable.c
+++ b/app/lua/lrotable.c
@@ -14,6 +14,12 @@
 #else
 #define ALIGNED_STRING (__attribute__((aligned(4))) char *)
 #endif
+
+#ifdef LUA_CROSS_COMPILER
+#undef IRAM_DATA_ATTR
+#define IRAM_DATA_ATTR
+#endif
+
 #define LA_LINES 32
 #define LA_SLOTS 4
 //#define COLLECT_STATS
@@ -36,13 +42,15 @@
  * Note that this hash does a couple of prime multiples and a modulus 2^X
  * with is all evaluated in H/W, and adequately randomizes the lookup.
  */
-#define HASH(a,b) ((((519*(size_t)(a)))>>4) + ((b) ? (b)->tsv.hash: 0))
+#define HASH(a,b) (unsigned)((((519*(size_t)(a)))>>4) + ((b) ? (b)->tsv.hash: 0))
 
-static struct {
+typedef struct {
   unsigned hash;
   unsigned addr:24;
   unsigned ndx:8;
-} cache[LA_LINES][LA_SLOTS];
+} cache_line_t;
+
+static cache_line_t IRAM_DATA_ATTR cache[LA_LINES][LA_SLOTS];
 
 #ifdef COLLECT_STATS
 unsigned cache_stats[3];
@@ -55,10 +63,10 @@ static int lookup_cache(unsigned hash, ROTable *rotable) {
   int i = (hash>>2) & (LA_LINES-1), j;
 
   for (j = 0; j<LA_SLOTS; j++) {
-    if (cache[i][j].hash == hash &&
-        ((size_t)rotable & 0xffffffu) == cache[i][j].addr) {
+    cache_line_t cl = cache[i][j];
+    if (cl.hash == hash && ((size_t)rotable & 0xffffffu) == cl.addr) {
       COUNT(0);
-      return cache[i][j].ndx;
+      return cl.ndx;
     }
   }
   COUNT(1);
@@ -67,14 +75,21 @@ static int lookup_cache(unsigned hash, ROTable *rotable) {
 
 static void update_cache(unsigned hash, ROTable *rotable, unsigned ndx) {
   int i = (hash)>>2 & (LA_LINES-1), j;
+#ifndef _MSC_VER
+  cache_line_t cl = {hash, (size_t) rotable, ndx};
+#else
+  cache_line_t cl;             // MSC doesn't allow non-scalar initialisers, which
+  cl.hash = hash;              // is a pity because xtensa gcc generates optimum   
+  cl.addr = (size_t) rotable;  // code using them.
+  cl.ndx  = ndx;
+#endif
+
   COUNT(2);
   if (ndx>0xffu)
     return;
   for (j = LA_SLOTS-1; j>0; j--)
     cache[i][j] = cache[i][j-1];
-  cache[i][0].hash = hash;
-  cache[i][0].addr = (size_t) rotable;
-  cache[i][0].ndx  = ndx;
+  cache[i][0] = cl;
 }
 /*
  * Find a string key entry in a rotable and return it.  Note that this internally
diff --git a/app/lwip/core/dns.c b/app/lwip/core/dns.c
index 90ea1124..9a77575d 100644
--- a/app/lwip/core/dns.c
+++ b/app/lwip/core/dns.c
@@ -222,7 +222,7 @@ static void dns_check_entries(void);
 /* DNS variables */
 static struct udp_pcb        *dns_pcb;
 static u8_t                   dns_seqno;
-static struct dns_table_entry dns_table[DNS_TABLE_SIZE];
+static struct dns_table_entry IRAM_DATA_ATTR dns_table[DNS_TABLE_SIZE];
 static ip_addr_t              dns_servers[DNS_MAX_SERVERS];
 /** Contiguous buffer for processing responses */
 //static u8_t                   dns_payload_buffer[LWIP_MEM_ALIGN_BUFFER(DNS_MSG_SIZE)];
diff --git a/app/modules/node.c b/app/modules/node.c
index db33dc25..7a01bac1 100644
--- a/app/modules/node.c
+++ b/app/modules/node.c
@@ -771,7 +771,7 @@ LROT_BEGIN(node)
   LROT_FUNCENTRY( dsleepMax, dsleepMax )
   LROT_FUNCENTRY( sleep, node_sleep )
 #ifdef PMSLEEP_ENABLE
-  PMSLEEP_INT_MAP,
+  PMSLEEP_INT_MAP
 #endif
 #ifdef DEVELOPMENT_TOOLS
   LROT_FUNCENTRY( readrcr, node_readrcr )
diff --git a/app/spiffs/spiffs.c b/app/spiffs/spiffs.c
index 794bc1a7..bfd47cba 100644
--- a/app/spiffs/spiffs.c
+++ b/app/spiffs/spiffs.c
@@ -28,10 +28,10 @@ static spiffs fs;
 #define MASK_1MB (0x100000-1)
 #define ALIGN (0x2000)
 
-static u8_t spiffs_work_buf[LOG_PAGE_SIZE*2];
+static u8_t IRAM_DATA_ATTR spiffs_work_buf[LOG_PAGE_SIZE*2];
 static u8_t spiffs_fds[sizeof(spiffs_fd) * SPIFFS_MAX_OPEN_FILES];
 #if SPIFFS_CACHE
-static u8_t myspiffs_cache[20 + (LOG_PAGE_SIZE+20)*4];
+static u8_t IRAM_DATA_ATTR myspiffs_cache[20 + (LOG_PAGE_SIZE+20)*4];
 #endif
 
 static s32_t my_spiffs_read(u32_t addr, u32_t size, u8_t *dst) {
diff --git a/app/user/user_main.c b/app/user/user_main.c
index 9f80fb9b..57501dde 100644
--- a/app/user/user_main.c
+++ b/app/user/user_main.c
@@ -144,7 +144,7 @@ void user_pre_init(void) {
         os_printf("system SPI FI size:%u, Flash size: %u\n", fs_size_code, flash_size );
     }
 
-    pt = os_malloc(i);  // We will work on and register a RAM copy of the PT
+    pt = os_malloc_iram(i);  // We will work on and register a copy of the PT in iRAM
     // Return if anything is amiss; The SDK will halt if the PT hasn't been registered
     if ( !rcr_pt || !pt || n * sizeof(partition_item_t) != i) {
         return;
diff --git a/ld/nodemcu.ld b/ld/nodemcu.ld
index ab08e61a..294b2605 100644
--- a/ld/nodemcu.ld
+++ b/ld/nodemcu.ld
@@ -124,6 +124,7 @@ SECTIONS
     /* *libwps.a:*(.literal .text) - tested that safe to keep in iROM */
 
     *(.iram.text .iram0.text .iram0.text.*)
+    *(.iram0.data.*)
 
     *(.stub .gnu.warning .gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
 
diff --git a/tools/nodemcu-partition.py b/tools/nodemcu-partition.py
index 23668082..c168729c 100755
--- a/tools/nodemcu-partition.py
+++ b/tools/nodemcu-partition.py
@@ -22,7 +22,8 @@
 
 import os
 import sys
-sys.path.append(os.path.realpath(os.path.dirname(__file__) + '/toolchains/'))
+print os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.dirname(os.path.realpath(__file__)) + '/toolchains/')
 import esptool
 
 import io