diff --git a/sw/kernel/devices/rtc.h b/sw/kernel/devices/rtc.h
index 913e7c6..6158d30 100644
--- a/sw/kernel/devices/rtc.h
+++ b/sw/kernel/devices/rtc.h
@@ -6,6 +6,12 @@
 #define RTC_CMD_ADDR    0xeffe
 #define RTC_DAT_ADDR    0xefff
 
+#define RTC_THRESHOLD       0x00
+#define RTC_INCREMENT       0x10
+#define RTC_IRQ_THRESHOLD   0x20
+#define RTC_OUTPUT          0x30
+#define RTC_CONTROL         0x30
+
 /* initialize RTC with default values */
 void init_rtc(void);
 
@@ -13,4 +19,7 @@ void init_rtc(void);
 void handle_rtc(void);
 
 
+void rtc_set(uint32_t val, uint8_t idx);
+
+
 #endif
\ No newline at end of file
diff --git a/sw/kernel/devices/rtc.s b/sw/kernel/devices/rtc.s
index 5f47134..3c34513 100644
--- a/sw/kernel/devices/rtc.s
+++ b/sw/kernel/devices/rtc.s
@@ -2,8 +2,11 @@
 
 .importzp tmp1
 
+.import popa
+
 .export _init_rtc
 .export _handle_rtc
+.export _rtc_set
 
 RTC_CMD = $effe
 RTC_DAT = $efff
@@ -86,7 +89,19 @@ IRQ_THRESHOLD_3     = $00
     sta RTC_DAT
     
     rts
+.endproc
 
+; void rtc_set(uint32_t val, uint8_t idx);
+.proc _rtc_set
+    tay             ; move cmd to Y
+    ldx #$04
+L1: sty RTC_CMD     ; store cmd+idx to CMD    
+    jsr popa        ; pop 1 byte of argument
+    sta RTC_DAT     ; write it to data
+    iny             ; increase index
+    dex         
+    bne L1          ; repeat 4 times
+    rts
 .endproc
 
 
diff --git a/sw/kernel/kernel.c b/sw/kernel/kernel.c
index 035f0f1..e81a8fc 100644
--- a/sw/kernel/kernel.c
+++ b/sw/kernel/kernel.c
@@ -36,6 +36,9 @@ int main() {
 
     register_irq(&handle_rtc_interrupt, 0);
 
+    rtc_set(0xaaaa, RTC_THRESHOLD);
+    rtc_set(0xbbbb, RTC_IRQ_THRESHOLD);
+
     asm volatile("cli");
 
     // cputs("Initialize Serial\n");