diff --git a/src/clock.c b/src/clock.c
index 5a30e35..9afa71d 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -226,6 +226,7 @@ timer_setup(void)
 static void
 handle_1a00(struct bregs *regs)
 {
+    yield();
     u32 ticks = GET_BDA(timer_counter);
     regs->cx = ticks >> 16;
     regs->dx = ticks;
diff --git a/src/config.h b/src/config.h
index 5316f22..226919b 100644
--- a/src/config.h
+++ b/src/config.h
@@ -16,9 +16,9 @@
 #define CONFIG_COREBOOT 0
 
 // Control how verbose debug output is.
-#define CONFIG_DEBUG_LEVEL 1
+#define CONFIG_DEBUG_LEVEL 8
 // Send debugging information to serial port
-#define CONFIG_DEBUG_SERIAL 0
+#define CONFIG_DEBUG_SERIAL 1
 // Screen writes are also sent to debug ports.
 #define CONFIG_SCREEN_AND_DEBUG 1
 
diff --git a/src/kbd.c b/src/kbd.c
index 44dce57..72f4c02 100644
--- a/src/kbd.c
+++ b/src/kbd.c
@@ -51,6 +51,7 @@ enqueue_key(u8 scan_code, u8 ascii_code)
 static void
 dequeue_key(struct bregs *regs, int incr, int extended)
 {
+    yield();
     u16 buffer_head;
     u16 buffer_tail;
     for (;;) {
@@ -530,9 +531,19 @@ process_key(u8 key)
         // allow for keyboard intercept
         u32 eax = (0x4f << 8) | key;
         u32 flags;
+#if 0
         call16_simpint(0x15, &eax, &flags);
         if (!(flags & F_CF))
             return;
+#else
+        struct bregs br;
+        memset(&br, 0, sizeof(br));
+        br.eax = eax;
+        call16_int(0x15, &br);
+        flags = br.flags;
+        if (!(flags & F_CF))
+            return;
+#endif
         key = eax;
     }
     __process_key(key);