diff --git a/src/computer.c b/src/computer.c
index fd39f71..577d21e 100644
--- a/src/computer.c
+++ b/src/computer.c
@@ -14,13 +14,78 @@ nn_architecture *nn_getArchitecture(nn_computer *computer);
 nn_architecture *nn_getNextArchitecture(nn_computer *computer);
 void nn_setNextArchitecture(nn_computer *computer, nn_architecture *arch);
 void nn_deleteComputer(nn_computer *computer);
-void nn_pushSignal(nn_computer *computer, nn_value *values, size_t len);
-nn_value nn_fetchSignalValue(nn_computer *computer, size_t index);
-void nn_popSignal(nn_computer *computer);
-void nn_addUser(nn_computer *computer, const char *name);
-void nn_deleteUser(nn_computer *computer, const char *name);
-const char *nn_indexUser(nn_computer *computer, size_t idx);
-bool nn_isUser(nn_computer *computer, const char *name);
+
+const char *nn_pushSignal(nn_computer *computer, nn_value *values, size_t len) {
+    if(len > NN_MAX_SIGNAL_VALS) return "too many values";
+    if(len == 0) return "missing event";
+    // no OOM for you hehe
+    if(nn_measurePacketSize(values, len) > NN_MAX_SIGNAL_SIZE) {
+        return "too big";
+    }
+    if(computer->signalCount == NN_MAX_SIGNALS) return "too many signals";
+    computer->signals[computer->signalCount].len = len;
+    for(size_t i = 0; i < len; i++) {
+        computer->signals[computer->signalCount].values[i] = values[i];
+    }
+    computer->signalCount++;
+    return NULL;
+}
+
+nn_value nn_fetchSignalValue(nn_computer *computer, size_t index) {
+    nn_signal *p = computer->signals + computer->signalCount - 1;
+    if(index >= p->len) return nn_values_nil();
+    return p->values[index];
+}
+
+size_t nn_signalSize(nn_computer *computer) {
+    if(computer->signalCount == 0) return 0;
+    return computer->signals[computer->signalCount-1].len;
+}
+
+void nn_popSignal(nn_computer *computer) {
+    if(computer->signalCount == 0) return;
+    nn_signal *p = computer->signals + computer->signalCount - 1;
+    for(size_t i = 0; i < p->len; i++) {
+        nn_values_drop(p->values[i]);
+    }
+    computer->signalCount--;
+}
+
+const char *nn_addUser(nn_computer *computer, const char *name) {
+    if(computer->userCount == NN_MAX_USERS) return "too many users";
+    char *user = nn_strdup(name);
+    if(user == NULL) return "out of memory";
+    computer->users[computer->userCount] = user;
+    computer->userCount++;
+    return NULL;
+}
+
+void nn_deleteUser(nn_computer *computer, const char *name) {
+    size_t j = 0;
+    for(size_t i = 0; i < computer->userCount; i++) {
+        char *user = computer->users[i];
+        if(strcmp(user, name) == 0) {
+            nn_free(user);
+        } else {
+            computer->users[j] = user;
+            j++;
+        }
+    }
+    computer->userCount = j;
+}
+
+const char *nn_indexUser(nn_computer *computer, size_t idx) {
+    if(idx >= computer->userCount) return NULL;
+    return computer->users[idx];
+}
+
+bool nn_isUser(nn_computer *computer, const char *name) {
+    if(computer->userCount == 0) return true;
+    for(size_t i = 0; i < computer->userCount; i++) {
+        if(strcmp(computer->users[i], name) == 0) return true;
+    }
+    return false;
+}
 
 int nn_getState(nn_computer *computer) {
     return computer->state;
diff --git a/src/computer.h b/src/computer.h
index 2405097..af11856 100644
--- a/src/computer.h
+++ b/src/computer.h
@@ -3,6 +3,11 @@
 
 #include "neonucleus.h"
 
+typedef struct nn_signal {
+    size_t len;
+    nn_value values[NN_MAX_SIGNAL_VALS];
+} nn_signal;
+
 typedef struct nn_computer {
     char state;
     bool allocatedError;
@@ -25,6 +30,8 @@ typedef struct nn_computer {
     size_t userCount;
     size_t energy;
     size_t maxEnergy;
+    nn_signal signals[NN_MAX_SIGNALS];
+    size_t signalCount;
 } nn_computer;
 
 #endif
diff --git a/src/neonucleus.h b/src/neonucleus.h
index 0fa6c50..f903ba2 100644
--- a/src/neonucleus.h
+++ b/src/neonucleus.h
@@ -55,6 +55,8 @@
 #define NN_MAX_SIGNALS 32
 #define NN_MAX_SIGNAL_VALS 32
 #define NN_MAX_USERDATA 1024
+#define NN_MAX_USER_SIZE 128
+#define NN_MAX_SIGNAL_SIZE 8192
 
 typedef struct nn_guard nn_guard;
 typedef struct nn_universe nn_universe;
@@ -158,10 +160,11 @@ nn_architecture *nn_getArchitecture(nn_computer *computer);
 nn_architecture *nn_getNextArchitecture(nn_computer *computer);
 void nn_setNextArchitecture(nn_computer *computer, nn_architecture *arch);
 void nn_deleteComputer(nn_computer *computer);
-void nn_pushSignal(nn_computer *computer, nn_value *values, size_t len);
+const char *nn_pushSignal(nn_computer *computer, nn_value *values, size_t len);
 nn_value nn_fetchSignalValue(nn_computer *computer, size_t index);
+size_t nn_signalSize(nn_computer *computer);
 void nn_popSignal(nn_computer *computer);
-void nn_addUser(nn_computer *computer, const char *name);
+const char *nn_addUser(nn_computer *computer, const char *name);
 void nn_deleteUser(nn_computer *computer, const char *name);
 const char *nn_indexUser(nn_computer *computer, size_t idx);
 bool nn_isUser(nn_computer *computer, const char *name);
@@ -282,4 +285,10 @@ bool nn_toBoolean(nn_value val);
 const char *nn_toCString(nn_value val);
 const char *nn_toString(nn_value val, size_t *len);
 
+/*
+ * Computes the "packet size" of the values, using the same algorithm as OC.
+ * This is used by pushSignal to check the size
+ */
+size_t nn_measurePacketSize(nn_value *vals, size_t len);
+
 #endif
diff --git a/src/value.c b/src/value.c
index b0b1ec3..d10da19 100644
--- a/src/value.c
+++ b/src/value.c
@@ -154,3 +154,28 @@ nn_pair nn_values_getPair(nn_value obj, size_t idx) {
     if(idx >= obj.table->len) return badPair;
     return obj.table->pairs[idx];
 }
+
+size_t nn_measurePacketSize(nn_value *vals, size_t len) {
+    size_t size = 0;
+    for(size_t i = 0; i < len; i++) {
+        nn_value val = vals[i];
+        size += 2;
+        if(val.tag == NN_VALUE_INT || val.tag == NN_VALUE_NUMBER) {
+            size += 8;
+        } else if(val.tag == NN_VALUE_STR) {
+            size_t len = val.string->len;
+            if(len == 0) len = 1; // ask OC
+            size += len;
+        } else if(val.tag == NN_VALUE_CSTR) {
+            size_t len = strlen(val.cstring);
+            if(len == 0) len = 1; // ask OC
+            size += len;
+        } else if(val.tag == NN_VALUE_BOOL || val.tag == NN_VALUE_NIL) {
+            size += 4;
+        } else {
+            // yeah no fuck off
+            return SIZE_MAX;
+        }
+    }
+    return size;
+}