Add: PIT (sysclock)

timer.c

@@ -0,0 +1,26 @@
+#include "system.h"
+#include "stdio.h"
+
+int timer_ticks = 0;
+
+void timer_handler()
+{
+	timer_ticks++;
+
+	if(timer_ticks % 18 == 0)
+	{
+		puts("One second has passed\n");
+	}
+}
+
+void timer_install()
+{
+	irq_install_handler(0, timer_handler);
+}
+
+void delay(int ticks)
+{
+	unsigned long eticks;
+	eticks = timer_ticks + ticks;
+	while ((unsigned long)timer_ticks < eticks);
+}