diff --git a/intro/Makefile b/intro/Makefile
new file mode 100644
index 0000000..b5c1fe7
--- /dev/null
+++ b/intro/Makefile
@@ -0,0 +1,18 @@
+
+all: cpu mem threads io
+
+clean:
+	rm -f cpu mem threads io
+
+cpu: cpu.c common.h
+	gcc -o cpu cpu.c -Wall
+
+mem: mem.c common.h
+	gcc -o mem mem.c -Wall
+
+threads: threads.c common.h common_threads.h
+	gcc -o threads threads.c -Wall -pthread
+
+io: io.c common.h
+	gcc -o io io.c -Wall
+
diff --git a/intro/common.h b/intro/common.h
new file mode 100644
index 0000000..1202765
--- /dev/null
+++ b/intro/common.h
@@ -0,0 +1,21 @@
+#ifndef __common_h__
+#define __common_h__
+
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <assert.h>
+
+double GetTime() {
+    struct timeval t;
+    int rc = gettimeofday(&t, NULL);
+    assert(rc == 0);
+    return (double) t.tv_sec + (double) t.tv_usec/1e6;
+}
+
+void Spin(int howlong) {
+    double t = GetTime();
+    while ((GetTime() - t) < (double) howlong)
+	; // do nothing in loop
+}
+
+#endif // __common_h__
diff --git a/intro/common_threads.h b/intro/common_threads.h
new file mode 100644
index 0000000..a587122
--- /dev/null
+++ b/intro/common_threads.h
@@ -0,0 +1,33 @@
+#ifndef __common_threads_h__
+#define __common_threads_h__
+
+#include <pthread.h>
+#include <assert.h>
+#include <sched.h>
+
+#ifdef __linux__
+#include <semaphore.h>
+#endif
+
+#define Pthread_create(thread, attr, start_routine, arg) assert(pthread_create(thread, attr, start_routine, arg) == 0);
+#define Pthread_join(thread, value_ptr)                  assert(pthread_join(thread, value_ptr) == 0);
+
+#define Pthread_mutex_lock(m)                            assert(pthread_mutex_lock(m) == 0);
+#define Pthread_mutex_unlock(m)                          assert(pthread_mutex_unlock(m) == 0);
+#define Pthread_cond_signal(cond)                        assert(pthread_cond_signal(cond) == 0);
+#define Pthread_cond_wait(cond, mutex)                   assert(pthread_cond_wait(cond, mutex) == 0);
+
+#define Mutex_init(m)                                    assert(pthread_mutex_init(m, NULL) == 0);
+#define Mutex_lock(m)                                    assert(pthread_mutex_lock(m) == 0);
+#define Mutex_unlock(m)                                  assert(pthread_mutex_unlock(m) == 0);
+#define Cond_init(cond)                                  assert(pthread_cond_init(cond, NULL) == 0);
+#define Cond_signal(cond)                                assert(pthread_cond_signal(cond) == 0);
+#define Cond_wait(cond, mutex)                           assert(pthread_cond_wait(cond, mutex) == 0);
+
+#ifdef __linux__
+#define Sem_init(sem, value)                             assert(sem_init(sem, 0, value) == 0);
+#define Sem_wait(sem)                                    assert(sem_wait(sem) == 0);
+#define Sem_post(sem)                                    assert(sem_post(sem) == 0);
+#endif // __linux__
+
+#endif // __common_threads_h__
diff --git a/intro/cpu.c b/intro/cpu.c
new file mode 100644
index 0000000..3154456
--- /dev/null
+++ b/intro/cpu.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "common.h"
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2) {
+	fprintf(stderr, "usage: cpu <string>\n");
+	exit(1);
+    }
+    char *str = argv[1];
+
+    while (1) {
+	printf("%s\n", str);
+	Spin(1);
+    }
+    return 0;
+}
+
diff --git a/intro/io.c b/intro/io.c
new file mode 100644
index 0000000..617fd4d
--- /dev/null
+++ b/intro/io.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <string.h>
+
+int main(int argc, char *argv[]) {
+    int fd = open("/tmp/file", O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
+    assert(fd >= 0);
+    char buffer[20];
+    sprintf(buffer, "hello world\n");
+    int rc = write(fd, buffer, strlen(buffer));
+    assert(rc == (strlen(buffer)));
+    fsync(fd);
+    close(fd);
+    return 0;
+}
+
diff --git a/intro/mem.c b/intro/mem.c
new file mode 100644
index 0000000..a82d34b
--- /dev/null
+++ b/intro/mem.c
@@ -0,0 +1,23 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "common.h"
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) { 
+	fprintf(stderr, "usage: mem <value>\n"); 
+	exit(1); 
+    } 
+    int *p; 
+    p = malloc(sizeof(int));
+    assert(p != NULL);
+    printf("(%d) addr pointed to by p: %p\n", (int) getpid(), p);
+    *p = atoi(argv[1]); // assign value to addr stored in p
+    while (1) {
+	Spin(1);
+	*p = *p + 1;
+	printf("(%d) value of p: %d\n", getpid(), *p);
+    }
+    return 0;
+}
+
diff --git a/intro/threads.c b/intro/threads.c
new file mode 100644
index 0000000..5c7e044
--- /dev/null
+++ b/intro/threads.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "common.h"
+#include "common_threads.h"
+
+volatile int counter = 0; 
+int loops;
+
+void *worker(void *arg) {
+    int i;
+    for (i = 0; i < loops; i++) {
+	counter++;
+    }
+    return NULL;
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) { 
+	fprintf(stderr, "usage: threads <loops>\n"); 
+	exit(1); 
+    } 
+    loops = atoi(argv[1]);
+    pthread_t p1, p2;
+    printf("Initial value : %d\n", counter);
+    Pthread_create(&p1, NULL, worker, NULL); 
+    Pthread_create(&p2, NULL, worker, NULL);
+    Pthread_join(p1, NULL);
+    Pthread_join(p2, NULL);
+    printf("Final value   : %d\n", counter);
+    return 0;
+}
+