diff --git a/cores/esp8266/Arduino.h b/cores/esp8266/Arduino.h
index 7ebc77b79..89dbff873 100644
--- a/cores/esp8266/Arduino.h
+++ b/cores/esp8266/Arduino.h
@@ -107,20 +107,6 @@ void timer1_attachInterrupt(void (*userFunc)(void));
 void timer1_detachInterrupt(void);
 void timer1_write(uint32_t ticks); //maximum ticks 8388607
 
-// timer0 is a special CPU timer that has very high resolution but with
-// limited control.
-// it uses CCOUNT (ESP.GetCycleCount()) as the non-resetable timer counter
-// it does not support divide, type, or reload flags
-// it is auto-disabled when the compare value matches CCOUNT
-// it is auto-enabled when the compare value changes
-#define timer0_interrupted()    (ETS_INTR_PENDING() & (_BV(ETS_COMPARE0_INUM)))
-#define timer0_read() (ESP.getCycleCompare0())
-#define timer0_write(ticks) (ESP.setCycleCompare0(ticks))
-
-void timer0_isr_init(void);
-void timer0_attachInterrupt(void(*userFunc)(void));
-void timer0_detachInterrupt(void);
-
 // undefine stdlib's abs if encountered
 #ifdef abs
 #undef abs
@@ -140,13 +126,13 @@ void ets_intr_unlock();
 // level 15 will disable ALL interrupts, 
 // level 0 will disable most software interrupts
 //
-#define xt_disable_interrupts(state, level) __asm__ __volatile__("rsil %0," __STRINGIFY(level) : "=a" (state))
+#define xt_disable_interrupts(state, level) __asm__ __volatile__("rsil %0," __STRINGIFY(level) "; esync; isync; dsync" : "=a" (state))
 #define xt_enable_interrupts(state)  __asm__ __volatile__("wsr %0,ps; esync" :: "a" (state) : "memory")
 
 extern uint32_t interruptsState;
 
 #define interrupts() xt_enable_interrupts(interruptsState)
-#define noInterrupts() __asm__ __volatile__("rsil %0,15" : "=a" (interruptsState))
+#define noInterrupts() __asm__ __volatile__("rsil %0,15; esync; isync; dsync" : "=a" (interruptsState))
 
 #define clockCyclesPerMicrosecond() ( F_CPU / 1000000L )
 #define clockCyclesToMicroseconds(a) ( (a) / clockCyclesPerMicrosecond() )
diff --git a/cores/esp8266/Esp.h b/cores/esp8266/Esp.h
index c887c89e9..5e356459e 100644
--- a/cores/esp8266/Esp.h
+++ b/cores/esp8266/Esp.h
@@ -99,31 +99,15 @@ class EspClass {
         uint32_t getFlashChipSizeByChipId(void);
 
         inline uint32_t getCycleCount(void);
-        inline uint32_t getCycleCompare0(void);
-        inline void setCycleCompare0(uint32_t count);
 };
 
 uint32_t EspClass::getCycleCount(void)
 {
     uint32_t ccount;
-    __asm__ __volatile__("esync; rsr %0,ccount":"=a" (ccount));
+    __asm__ __volatile__("rsr %0,ccount":"=a" (ccount));
     return ccount;
 }
 
-// this returns a value in the range of (0 - 2^32)
-uint32_t EspClass::getCycleCompare0(void)
-{
-    uint32_t count;
-    __asm__ __volatile__("esync; rsr %0,ccompare0":"=a" (count));
-    return count;
-}
-
-// this takes a value in the range of (0 - 2^32)
-void EspClass::setCycleCompare0(uint32_t count)
-{
-    __asm__ __volatile__("wsr %0,ccompare0; esync"::"a" (count) : "memory");
-}
-
 extern EspClass ESP;
 
 #endif //ESP_H
diff --git a/cores/esp8266/core_esp8266_timer.c b/cores/esp8266/core_esp8266_timer.c
index 979ab0bfc..bfdd3692c 100644
--- a/cores/esp8266/core_esp8266_timer.c
+++ b/cores/esp8266/core_esp8266_timer.c
@@ -59,25 +59,3 @@ void timer1_disable(){
     T1C = 0;
     T1I = 0;
 }
-
-void(*timer0_user_cb)(void);
-
-void timer0_isr_handler(void *para){
-    if (timer0_user_cb) {
-        timer0_user_cb();
-    }
-}
-
-void timer0_isr_init(){
-    ETS_CCOMPARE0_INTR_ATTACH(timer0_isr_handler, NULL);
-}
-
-void timer0_attachInterrupt(void(*userFunc)(void)) {
-    timer1_user_cb = userFunc;
-    ETS_CCOMPARE0_ENABLE();
-}
-
-void timer0_detachInterrupt() {
-    timer1_user_cb = NULL;
-    ETS_CCOMPARE0_DISABLE();
-}
\ No newline at end of file
diff --git a/tools/sdk/include/ets_sys.h b/tools/sdk/include/ets_sys.h
index 3cdb51d2a..7908699bb 100644
--- a/tools/sdk/include/ets_sys.h
+++ b/tools/sdk/include/ets_sys.h
@@ -43,7 +43,6 @@ typedef void (*int_handler_t)(void*);
 #define ETS_GPIO_INUM       4
 #define ETS_UART_INUM       5
 #define ETS_UART1_INUM      5
-#define ETS_CCOMPARE0_INUM  6
 #define ETS_FRC_TIMER1_INUM 9  /* use edge*/
 
 #define ETS_INTR_LOCK() \
@@ -52,9 +51,6 @@ typedef void (*int_handler_t)(void*);
 #define ETS_INTR_UNLOCK() \
     ets_intr_unlock()
 
-#define ETS_CCOMPARE0_INTR_ATTACH(func, arg) \
-    ets_isr_attach(ETS_CCOMPARE0_INUM, (int_handler_t)(func), (void *)(arg))
-
 #define ETS_FRC_TIMER1_INTR_ATTACH(func, arg) \
     ets_isr_attach(ETS_FRC_TIMER1_INUM, (int_handler_t)(func), (void *)(arg))
 
@@ -73,18 +69,6 @@ typedef void (*int_handler_t)(void*);
 #define ETS_INTR_DISABLE(inum) \
     ets_isr_mask((1<<inum))
 
-{
-    uint32_t enabled;
-    __asm__ __volatile__("esync; rsr %0,intenable":"=a" (enabled));
-    return enabled;
-}
-
-{
-    uint32_t pending;
-    __asm__ __volatile__("esync; rsr %0,interrupt":"=a" (pending));
-    return pending;
-}
-
 #define ETS_SPI_INTR_ENABLE() \
     ETS_INTR_ENABLE(ETS_SPI_INUM)
 
@@ -94,12 +78,6 @@ typedef void (*int_handler_t)(void*);
 #define ETS_UART_INTR_DISABLE() \
     ETS_INTR_DISABLE(ETS_UART_INUM)
 
-#define ETS_CCOMPARE0_ENABLE() \
-	ETS_INTR_ENABLE(ETS_CCOMPARE0_INUM)
-
-#define ETS_CCOMPARE0_DISABLE() \
-	ETS_INTR_DISABLE(ETS_CCOMPARE0_INUM)
-
 #define ETS_FRC1_INTR_ENABLE() \
 	ETS_INTR_ENABLE(ETS_FRC_TIMER1_INUM)