diff --git a/lab6/demos/semaphore_1_mutex.c b/lab6/demos/semaphore_1_mutex.c
new file mode 100644
index 0000000..f04593e
--- /dev/null
+++ b/lab6/demos/semaphore_1_mutex.c
@@ -0,0 +1,84 @@
+#include<pthread.h>
+#include<semaphore.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<unistd.h>
+
+#define EMPTY -100
+
+struct args {
+    sem_t buf_sem;
+    int* buffer;
+    int buf_length;
+    pthread_mutex_t buf_lock;
+};
+
+void put(struct args* a, int item) {
+    pthread_mutex_lock(&a->buf_lock);
+    a->buf_length += 1;
+    a->buffer = reallocarray(a->buffer, a->buf_length, sizeof(int));
+    a->buffer[a->buf_length - 1] = item;
+    pthread_mutex_unlock(&a->buf_lock);
+}
+
+int get(struct args* a) {
+    int item;
+    pthread_mutex_lock(&a->buf_lock);
+
+    if (a->buf_length > 0) {
+        item = EMPTY;
+    } else {
+        item = a->buffer[0];
+        a->buf_length -= 1;
+        a->buffer += 1;
+    }
+
+    pthread_mutex_unlock(&a->buf_lock);
+    return item;
+}
+
+void *producer(void *arg) {
+    struct args* a = arg;
+
+    for (int i = 0; i < 100; i++) {
+        put(a, i);
+        sem_post(&a->buf_sem);
+    }
+    sleep(10);
+
+    for (int i = 0; i < 100; i++) {
+        put(a, i);
+        sem_post(&a->buf_sem);
+    }
+    return NULL;
+}
+
+void* consumer(void* arg) {
+    struct args* a = arg;
+
+    while (1) {
+        sem_wait(&a->buf_sem);
+        int tmp = get(a);
+        printf("%d\n", tmp);
+    }
+
+    return NULL;
+}
+
+struct args* make_args() {
+    struct args* a = malloc(sizeof(struct args));
+    sem_init(&a->buf_sem, 0, 1);
+    pthread_mutex_init(&a->buf_lock, NULL);
+
+    a->buffer = calloc(0, sizeof(int));
+    a->buf_length = 0;
+
+    return a;
+}
+
+int main(void) {
+    struct args* a = make_args();
+
+    pthread_t p1, p2, p3;
+
+}