diff --git a/src/Makefile b/src/Makefile
index ca829a2..d77522a 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,4 +1,4 @@
-OBJS=main.o log.o gpio.o
+OBJS=main.o sysinput.o log.o gpio.o msg_queue.o time_func.o
 LIBS=
 
 upiwin: $(OBJS)
diff --git a/src/gpio.c b/src/gpio.c
index 02f5e52..1e2f902 100644
--- a/src/gpio.c
+++ b/src/gpio.c
@@ -182,9 +182,23 @@ void Gpio_cleanup(void)
   }
 }
 
+int Gpio_read_buttons(void)
+{
+  int rc = 0;
+
+  if (gpio_input(GLINE_BUTTON1) == 0)
+    rc |= STATE_BUTTON1;
+  if (gpio_input(GLINE_BUTTON2) == 0)
+    rc |= STATE_BUTTON2;
+  if (gpio_input(GLINE_BUTTON3) == 0)
+    rc |= STATE_BUTTON3;
+  if (gpio_input(GLINE_BUTTON4) == 0)
+    rc |= STATE_BUTTON4;
+}
+
 int Gpio_poll_buttons(void)
 {
-  int new_state = 0;
+  int new_state = Gpio_read_buttons();
   int tmp, ndx, mask;
   
   if (gpio_input(GLINE_BUTTON1) == 0)
diff --git a/src/gpio.h b/src/gpio.h
index a1d48b7..416d4bc 100644
--- a/src/gpio.h
+++ b/src/gpio.h
@@ -3,6 +3,7 @@
 
 extern int Gpio_setup(void);
 extern void Gpio_cleanup(void);
+extern int Gpio_read_buttons(void);
 extern int Gpio_poll_buttons(void);
 
 #endif /* __GPIO_H_INCLUDED */
diff --git a/src/main.c b/src/main.c
index 0781b05..1490722 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,16 +1,42 @@
 #include <stdlib.h>
 #include "gpio.h"
 #include "log.h"
+#include "time_func.h"
+#include "sysinput.h"
 
 int main(int argc, char *argv[])
 {
+  MSG msg;
+  
+  TimeInit();
   if (Gpio_setup() != 0)
     return EXIT_FAILURE;
   atexit(Gpio_cleanup);
+  if (SysEnableInput() != 0)
+    return EXIT_FAILURE;
+  atexit(SysDisableInput);
 
   Log(LINFO, "System ready.");
 
-  for (;;) {
-    Gpio_poll_buttons();
+  for (;;)
+  {
+    if (MqPeek(Sys_Queue, &msg, PEEK_REMOVE))
+    {
+      switch (msg.message)
+      {
+	case WM_HWBUTTONDOWN:
+	  Log(LINFO, "Button %d was pressed.", (int)(msg.attrs[0]));
+	  break;
+
+	case WM_HWBUTTONUP:
+	  Log(LINFO, "Button %d was released.", (int)(msg.attrs[0]));
+	  break;
+
+	default:
+	  break;
+      }
+    }
   }
+  
+  return EXIT_SUCCESS;
 }
diff --git a/src/msg.h b/src/msg.h
new file mode 100644
index 0000000..c880d76
--- /dev/null
+++ b/src/msg.h
@@ -0,0 +1,20 @@
+#ifndef __MSG_H_INCLUDED
+#define __MSG_H_INCLUDED
+
+#include "wintype.h"
+
+#define MSG_ATTRCOUNT 2
+
+typedef tagMSG {
+  uintptr_t target;
+  unsigned message;
+  uintptr_t attrs[MSG_ATTRCOUNT];
+  TIMESTAMP timestamp;
+} MSG, *PMSG;
+
+#define WM_NULL           0x0000
+
+#define WM_HWBUTTONDOWN   0x0020
+#define WM_HWBUTTONUP     0x0021
+
+#endif /* __MSG_H_INCLUDED */
diff --git a/src/msg_queue.c b/src/msg_queue.c
new file mode 100644
index 0000000..9d89ae3
--- /dev/null
+++ b/src/msg_queue.c
@@ -0,0 +1,92 @@
+#include <stdlib.h>
+#include <pthread.h>
+#include "wintype.h"
+#include "time_func.h"
+#include "msg_queue.h"
+
+PMSG_QUEUE MqAlloc(int nentries)
+{
+  int sz = sizeof(MSG_QUEUE) + (nentries * sizeof(MSG));
+  PMSG_QUEUE rc;
+
+  rc = (PMSG_QUEUE)malloc(sz);
+  if (!rc)
+    return NULL;
+  memset(rc, 0 sz);
+  rc->startbound = &(rc->messagestore);
+  rc->endbound = rc->startbound + nentries;
+  rc->head = rc->tail = rc->startbound;
+  rc->nentries = nentries;
+  pthread_mutex_init(&(rc->mutex), NULL);
+  return rc;
+}
+
+void MqDestroy(PMSG_QUEUE queue)
+{
+  pthread_mutex_destroy(&(queue->mutex));
+  free(queue);
+}
+
+static void post_internal(PMSG_QUEUE queue, PMSG msg)
+{
+  PMSG nexttail;
+  
+  pthread_mutex_lock(&(queue->mutex));
+  nexttail = queue->tail + 1;
+  if (nexttail == queue->endbound)
+    nexttail = queue->startbound;
+  if (nexttail != queue->head)
+  {
+    memcpy(queue->tail, msg, sizeof(MSG));
+    queue->tail = nexttail;
+  }
+  /* else drop the message silently */
+  
+  pthread_mutex_unlock(&(queue->mutex));
+}
+
+void MqPost(PMSG_QUEUE queue, uintptr_t target, unsigned message, const uintptr_t *attrs, int nattrs)
+{
+  MSG tmpmsg;
+
+  memset(&tmpmsg, 0, sizeof(MSG));
+  tmpmsg.target = target;
+  tmpmsg.message = message;
+  if (nattrs > MSG_ATTRCOUNT)
+    nattrs = MSG_ATTRCOUNT;
+  if (nattrs > 0)
+    memcpy(&(tmpmsg.attrs), attrs, sizeof(uintptr_t) * nattrs);
+  tmpmsg.timestamp = TimeSinceStart();
+  post_internal(queue, &tmpmsg);
+}
+
+void MqPost1(PMSG_QUEUE queue, uintptr_t target, unsigned message, uintptr_t attr1)
+{
+  MSG tmpmsg;
+  
+  memset(&tmpmsg, 0, sizeof(MSG));
+  tmpmsg.target = target;
+  tmpmsg.message = message;
+  tmpmsg.attrs[0] = attr1;
+  tmpmsg.timestamp = TimeSinceStart();
+  post_internal(queue, &tmpmsg);
+}
+
+int MqPeek(PMSG_QUEUE queue, PMSG msg, unsigned flags)
+{
+  int rc = 0;
+  PMSG nexthead;
+  
+  pthread_mutex_lock(&(queue->mutex));
+  if (queue->head != queue->tail)
+  {
+    nexthead = queue->head + 1;
+    if (nexthead == queue->endbound)
+      nexthead = queue->startbound;
+    memcpy(msg, queue->head, sizeof(MSG));
+    if (flags & PEEK_REMOVE)
+      queue->head = nexthead;
+  }
+  pthread_mutex_unlock(&(queue->mutex));
+  return rc;
+}
diff --git a/src/msg_queue.h b/src/msg_queue.h
new file mode 100644
index 0000000..4b0ddc5
--- /dev/null
+++ b/src/msg_queue.h
@@ -0,0 +1,27 @@
+#ifndef __MSG_QUEUE_H_INCLUDED
+#define __MSG_QUEUE_H_INCLUDED
+
+#include "wintype.h"
+#include "msg.h"
+
+typedef struct tagMSG_QUEUE {
+  struct tagMSG_QUEUE *next;
+  PMSG startbound;
+  PMSG endbound;
+  PMSG head;
+  PMSG tail;
+  int nentries;
+  pthread_mutex_t mutex;
+  MSG messagestore[0];
+} MSG_QUEUE, *PMSG_QUEUE;
+
+#define PEEK_REMOVE   0x0001
+#define PEEK_NOREMOVE 0x0000
+
+extern PMSG_QUEUE MqAlloc(int nentries);
+extern void MqDestroy(PMSG_QUEUE queue);
+extern void MqPost(PMSG_QUEUE queue, uintptr_t target, unsigned message, const uintptr_t *attrs, int nattrs);
+extern void MqPost1(PMSG_QUEUE queue, uintptr_t target, unsigned message, uintptr_t attr1);
+extern int MqPeek(PMSG_QUEUE queue, PMSG msg, unsigned flags);
+
+#endif /* __MSG_QUEUE_H_INCLUDED */
diff --git a/src/sysinput.c b/src/sysinput.c
new file mode 100644
index 0000000..27fda6c
--- /dev/null
+++ b/src/sysinput.c
@@ -0,0 +1,68 @@
+#include <stddef.h>
+#include <signal.h>
+#include <pthread.h>
+#include "log.h"
+#include "msg_queue.h"
+#include "gpio.h"
+
+PMSG_QUEUE Sys_Queue = NULL;
+
+static pthread_t ithread;
+static volatile sig_atomic_t running = 1;
+static int last_bstate = 0;
+
+static void *input_thread(void *arg)
+{
+  int st, tmp, mask;
+  uintptr_t attr;
+  
+  while (running)
+  {
+    /* poll hardware buttons */
+    st = Gpio_read_buttons();
+    if (st != last_bstate)
+    {
+      tmp = last_state & ~st;
+      for (attr = 1, mask = 1; attr <= 4; attr++, mask <<= 1)
+      {
+	if (tmp & mask)
+	  MqPost1(Sys_Queue, 0, WM_HWBUTTONUP, attr);
+      }
+      tmp = st & ~last_state;
+      for (attr = 1, mask = 1; attr <= 4; attr++, mask <<= 1)
+      {
+	if (tmp & mask)
+	  MqPost1(Sys_Queue, 0, WM_HWBUTTONDOWN, attr);
+      }
+      last_bstate = st;
+    }
+
+    /* additional poll activity here */
+  }
+  return NULL;
+}
+
+int SysEnableInput(void)
+{
+  int rc;
+  
+  Sys_Queue = MqAlloc(64);
+  if (!Sys_Queue)
+  {
+    Log(LFATAL, "Unable to allocate system message queue.");
+    return 1;
+  }
+  running = 1;
+  rc = pthread_create(&ithread, NULL, input_thread, NULL);
+  if (rc != 0)
+    Log(LFATAL, "Unable to start system input thread (%d).", rc);
+  return rc;
+}
+
+void SysDisableInput(void)
+{
+  running = 0;
+  pthread_join(ithread, NULL);
+  MqDestroy(Sys_Queue);
+  Sys_Queue = NULL;
+}
diff --git a/src/sysinput.h b/src/sysinput.h
new file mode 100644
index 0000000..29b5a18
--- /dev/null
+++ b/src/sysinput.h
@@ -0,0 +1,11 @@
+#ifndef __SYSINPUT_H_INCLUDED
+#define __SYSINPUT_H_INCLUDED
+
+#include "msg_queue.h"
+
+extern PMSG_QUEUE Sys_Queue;
+
+extern int SysEnableInput(void);
+extern void SysDisableInput(void);
+
+#endif /* __SYSINPUT_H_INCLUDED */
diff --git a/src/time_func.c b/src/time_func.c
new file mode 100644
index 0000000..1ca8487
--- /dev/null
+++ b/src/time_func.c
@@ -0,0 +1,25 @@
+#include <stddef.h>
+#include <sys/time.h>
+#include "time_func.h"
+
+static TIMESTAMP start_timestamp = 0;
+
+TIMESTAMP TimeSinceEpoch(void)
+{
+  TIMESTAMP rc;
+  struct timeval tv;
+
+  gettimeofday(&tv, NULL);
+  rc = (tv.tv_sec * (TIMESTAMP)1000) + (tv.tv_usec / (TIMESTAMP)1000);
+  return rc;
+}
+
+TIMESTAMP TimeSinceStart(void)
+{
+  return TimeSinceEpoch() - start_timestamp;
+}
+
+void TimeInit(void)
+{
+  start_timestamp = TimeSinceEpoch();
+}
diff --git a/src/time_func.h b/src/time_func.h
new file mode 100644
index 0000000..80e0b14
--- /dev/null
+++ b/src/time_func.h
@@ -0,0 +1,10 @@
+#ifndef __TIMEFUNC_H_INCLUDED
+#define __TIMEFUNC_H_INCLUDED
+
+#include "wintype.h"
+
+extern TIMESTAMP TimeSinceEpoch(void);
+extern TIMESTAMP TimeSinceStart(void);
+extern void TimeInit(void);
+
+#endif /* __TIMEFUNC_H_INCLUDED */
diff --git a/src/wintype.h b/src/wintype.h
new file mode 100644
index 0000000..08d921b
--- /dev/null
+++ b/src/wintype.h
@@ -0,0 +1,8 @@
+#ifndef __WINTYPE_H_INCLUDED
+#define __WINTYPE_H_INCLUDED
+
+#include <stdint.h>
+
+typedef uint64_t TIMESTAMP;
+
+#endif /* __WINTYPE_H_INCLUDED */