diff --git a/userspace/main_user.c b/userspace/main_user.c
index 3a7c111..3d4925f 100644
--- a/userspace/main_user.c
+++ b/userspace/main_user.c
@@ -1,20 +1,15 @@
 #include "libc.h"
 #include "stdarg.h"
-
-int func_yolo()
-{
-        yolo();
-        return 0;
-}
+#include "tiny.h"
 
 int func_help()
 {
         printf("\nAvailable Commands:\n");
-        printf("        yolo\n");
         printf("        suicide\n");
         printf("        help\n");
         printf("        syscall5\n");
         printf("        alloc\n");
+        printf("        tiny: a tiny C interpreter\n");
         return 0;
 }
 
@@ -58,10 +53,6 @@ int main(int argc, char *argv[])
                 printf(">");
                 if (readline(buf, sizeof(buf)))
                         continue;
-                if (strcmp(buf, "yolo") == 0) {
-                        func_yolo();
-                        continue;
-                }
                 if (strcmp(buf, "help") == 0) {
                         func_help();
                         continue;
@@ -78,6 +69,10 @@ int main(int argc, char *argv[])
                         func_alloc();
                         continue;
                 }
+                if (strcmp(buf, "tiny") == 0) {
+                        func_tiny();
+                        continue;
+                }
         }
         return 0;
 }
diff --git a/userspace/tiny.c b/userspace/tiny.c
new file mode 100644
index 0000000..2263595
--- /dev/null
+++ b/userspace/tiny.c
@@ -0,0 +1,294 @@
+/* file: "tinyc.c" */
+
+/* Copyright (C) 2001 by Marc Feeley, All Rights Reserved. */
+
+#include "libc.h"
+
+/* 
+ * This is a compiler for the Tiny-C language.  Tiny-C is a
+ * considerably stripped down version of C and it is meant as a
+ * pedagogical tool for learning about compilers.  The integer global
+ * variables "a" to "z" are predefined and initialized to zero, and it
+ * is not possible to declare new variables.  The compiler reads the
+ * program from standard input and prints out the value of the
+ * variables that are not zero.  The grammar of Tiny-C in EBNF is:
+ *
+ *  <program> ::= <statement>
+ *  <statement> ::= "if" <paren_expr> <statement> |
+ *                  "if" <paren_expr> <statement> "else" <statement> |
+ *                  "while" <paren_expr> <statement> |
+ *                  "do" <statement> "while" <paren_expr> ";" |
+ *                  "{" { <statement> } "}" |
+ *                  <expr> ";" |
+ *                  ";"
+ *  <paren_expr> ::= "(" <expr> ")"
+ *  <expr> ::= <test> | <id> "=" <expr>
+ *  <test> ::= <sum> | <sum> "<" <sum>
+ *  <sum> ::= <term> | <sum> "+" <term> | <sum> "-" <term>
+ *  <term> ::= <id> | <int> | <paren_expr>
+ *  <id> ::= "a" | "b" | "c" | "d" | ... | "z"
+ *  <int> ::= <an_unsigned_decimal_integer>
+ *
+ * Here are a few invocations of the compiler:
+ *
+ * % echo "a=b=c=2<3;" | ./a.out
+ * a = 1
+ * b = 1
+ * c = 1
+ * % echo "{ i=1; while (i<100) i=i+i; }" | ./a.out
+ * i = 128
+ * % echo "{ i=125; j=100; while (i-j) if (i<j) j=j-i; else i=i-j; }" | ./a.out
+ * i = 25
+ * j = 25
+ * % echo "{ i=1; do i=i+10; while (i<50); }" | ./a.out
+ * i = 51
+ * % echo "{ i=1; while ((i=i+10)<50) ; }" | ./a.out
+ * i = 51
+ * % echo "{ i=7; if (i<5) x=1; if (i<10) y=2; }" | ./a.out
+ * i = 7
+ * y = 2
+ *
+ * The compiler does a minimal amount of error checking to help
+ * highlight the structure of the compiler.
+ */
+
+
+/*---------------------------------------------------------------------------*/
+
+/* Lexer. */
+
+enum { DO_SYM, ELSE_SYM, IF_SYM, WHILE_SYM, LBRA, RBRA, LPAR, RPAR,
+       PLUS, MINUS, LESS, SEMI, EQUAL, INT, ID, EOI };
+
+char *words[] = { "do", "else", "if", "while", NULL };
+
+int ch = ' ';
+int sym = 0;
+int int_val = 0;
+char id_name[100];
+
+void syntax_error() { printf("syntax error\n"); _exit(1); }
+
+void next_ch() { ch = getchar();};
+
+void next_sym()
+{ again: switch (ch)
+    { case ' ': case '\n': next_ch(); goto again;
+      case '\e': sym = EOI ; break; //escape
+      case '{': next_ch(); sym = LBRA; break;
+      case '}': next_ch(); sym = RBRA; break;
+      case '(': next_ch(); sym = LPAR; break;
+      case ')': next_ch(); sym = RPAR; break;
+      case '+': next_ch(); sym = PLUS; break;
+      case '-': next_ch(); sym = MINUS; break;
+      case '<': next_ch(); sym = LESS; break;
+      case ';': next_ch(); sym = SEMI; break;
+      case '=': next_ch(); sym = EQUAL; break;
+      default:
+        if (ch >= '0' && ch <= '9')
+          { int_val = 0; /* missing overflow check */
+            while (ch >= '0' && ch <= '9')
+              { int_val = int_val*10 + (ch - '0'); next_ch(); }
+            sym = INT;
+          }
+        else if (ch >= 'a' && ch <= 'z')
+          { int i = 0; /* missing overflow check */
+            while ((ch >= 'a' && ch <= 'z') || ch == '_')
+              { id_name[i++] = ch; next_ch(); }
+            id_name[i] = '\0';
+            sym = 0;
+            while (words[sym] != NULL && strcmp(words[sym], id_name) != 0)
+              sym++;
+            if (words[sym] == NULL) {
+                if (id_name[1] == '\0')
+                    sym = ID;
+                else
+                    syntax_error();
+            }
+          }
+        else
+          syntax_error();
+    }
+}
+
+/*---------------------------------------------------------------------------*/
+
+/* Parser. */
+
+enum { VAR, CST, ADD, SUB, LT, SET,
+       IF1, IF2, WHILE, DO, EMPTY, SEQ, EXPR, PROG };
+
+struct node { int kind; struct node *o1, *o2, *o3; int val; };
+typedef struct node node;
+
+node *new_node(int k)
+{ node *x = (node*)malloc(sizeof(node)); x->kind = k; return x; }
+
+node *paren_expr(); /* forward declaration */
+
+node *term()  /* <term> ::= <id> | <int> | <paren_expr> */
+{ node *x;
+  if (sym == ID) { x=new_node(VAR); x->val=id_name[0]-'a'; next_sym(); }
+  else if (sym == INT) { x=new_node(CST); x->val=int_val; next_sym(); }
+  else x = paren_expr();
+  return x;
+}
+
+node *sum()  /* <sum> ::= <term> | <sum> "+" <term> | <sum> "-" <term> */
+{ node *t, *x = term();
+  while (sym == PLUS || sym == MINUS)
+    { t=x; x=new_node(sym==PLUS?ADD:SUB); next_sym(); x->o1=t; x->o2=term(); }
+  return x;
+}
+
+node *test()  /* <test> ::= <sum> | <sum> "<" <sum> */
+{ node *t, *x = sum();
+  if (sym == LESS)
+    { t=x; x=new_node(LT); next_sym(); x->o1=t; x->o2=sum(); }
+  return x;
+}
+
+node *expr()  /* <expr> ::= <test> | <id> "=" <expr> */
+{ node *t, *x;
+  if (sym != ID) return test();
+  x = test();
+  if (x->kind == VAR && sym == EQUAL)
+    { t=x; x=new_node(SET); next_sym(); x->o1=t; x->o2=expr(); }
+  return x;
+}
+
+node *paren_expr()  /* <paren_expr> ::= "(" <expr> ")" */
+{ node *x;
+  if (sym == LPAR) next_sym(); else syntax_error();
+  x = expr();
+  if (sym == RPAR) next_sym(); else syntax_error();
+  return x;
+}
+
+node *statement()
+{ node *t, *x;
+  if (sym == IF_SYM)  /* "if" <paren_expr> <statement> */
+    { x = new_node(IF1);
+      next_sym();
+      x->o1 = paren_expr();
+      x->o2 = statement();
+      if (sym == ELSE_SYM)  /* ... "else" <statement> */
+        { x->kind = IF2;
+          next_sym();
+          x->o3 = statement();
+        }
+    }
+  else if (sym == WHILE_SYM)  /* "while" <paren_expr> <statement> */
+    { x = new_node(WHILE);
+      next_sym();
+      x->o1 = paren_expr();
+      x->o2 = statement();
+    }
+  else if (sym == DO_SYM)  /* "do" <statement> "while" <paren_expr> ";" */
+    { x = new_node(DO);
+      next_sym();
+      x->o1 = statement();
+      if (sym == WHILE_SYM) next_sym(); else syntax_error();
+      x->o2 = paren_expr();
+      if (sym == SEMI) next_sym(); else syntax_error();
+    }
+  else if (sym == SEMI)  /* ";" */
+    { x = new_node(EMPTY); next_sym(); }
+  else if (sym == LBRA)  /* "{" { <statement> } "}" */
+    { x = new_node(EMPTY);
+      next_sym();
+      while (sym != RBRA)
+        { t=x; x=new_node(SEQ); x->o1=t; x->o2=statement(); }
+      next_sym();
+    }
+  else  /* <expr> ";" */
+    { x = new_node(EXPR);
+      x->o1 = expr();
+      if (sym == SEMI) next_sym(); else syntax_error();
+    }
+  return x;
+}
+
+node *program()  /* <program> ::= <statement> */
+{ node *x = new_node(PROG);
+  next_sym(); x->o1 = statement(); if (sym != EOI) syntax_error();
+  return x;
+}
+
+/*---------------------------------------------------------------------------*/
+
+/* Code generator. */
+
+enum { IFETCH, ISTORE, IPUSH, IPOP, IADD, ISUB, ILT, JZ, JNZ, JMP, HALT };
+
+typedef char code;
+code object[1000], *here = object;
+
+void g(code c) { *here++ = c; } /* missing overflow check */
+code *hole() { return here++; }
+void fix(code *src, code *dst) { *src = dst-src; } /* missing overflow check */
+
+void c(node *x)
+{ code *p1, *p2;
+  switch (x->kind)
+    { case VAR  : g(IFETCH); g(x->val); break;
+      case CST  : g(IPUSH); g(x->val); break;
+      case ADD  : c(x->o1); c(x->o2); g(IADD); break;
+      case SUB  : c(x->o1); c(x->o2); g(ISUB); break;
+      case LT   : c(x->o1); c(x->o2); g(ILT); break;
+      case SET  : c(x->o2); g(ISTORE); g(x->o1->val); break;
+      case IF1  : c(x->o1); g(JZ); p1=hole(); c(x->o2); fix(p1,here); break;
+      case IF2  : c(x->o1); g(JZ); p1=hole(); c(x->o2); g(JMP); p2=hole();
+                  fix(p1,here); c(x->o3); fix(p2,here); break;
+      case WHILE: p1=here; c(x->o1); g(JZ); p2=hole(); c(x->o2);
+                  g(JMP); fix(hole(),p1); fix(p2,here); break;
+      case DO   : p1=here; c(x->o1); c(x->o2); g(JNZ); fix(hole(),p1); break;
+      case EMPTY: break;
+      case SEQ  : c(x->o1); c(x->o2); break;
+      case EXPR : c(x->o1); g(IPOP); break;
+      case PROG : c(x->o1); g(HALT); break;
+    }
+}
+
+/*---------------------------------------------------------------------------*/
+
+/* Virtual machine. */
+
+int globals[26];
+
+void run()
+{ int stack[500], *sp = stack;
+  code *pc = object;
+  again: switch (*pc++)
+    { case IFETCH: *sp++ = globals[(unsigned int)(*pc++)];               goto again;
+      case ISTORE: globals[(unsigned int)(*pc++)] = sp[-1];              goto again;
+      case IPUSH : *sp++ = *pc++;                        goto again;
+      case IPOP  : --sp;                                 goto again;
+      case IADD  : sp[-2] = sp[-2] + sp[-1]; --sp;       goto again;
+      case ISUB  : sp[-2] = sp[-2] - sp[-1]; --sp;       goto again;
+      case ILT   : sp[-2] = sp[-2] < sp[-1]; --sp;       goto again;
+      case JMP   : pc += *pc;                            goto again;
+      case JZ    : if (*--sp == 0) pc += *pc; else pc++; goto again;
+      case JNZ   : if (*--sp != 0) pc += *pc; else pc++; goto again;
+    }
+}
+
+/*---------------------------------------------------------------------------*/
+
+/* Main program. */
+
+int func_tiny()
+{ int i;
+
+  c(program());
+
+  for (i=0; i<26; i++)
+    globals[i] = 0;
+  run();
+  for (i=0; i<26; i++)
+    if (globals[i] != 0)
+      printf("%c = %d\n", 'a'+i, globals[i]);
+
+  return 0;
+}
+
diff --git a/userspace/tiny.h b/userspace/tiny.h
new file mode 100644
index 0000000..435c1e9
--- /dev/null
+++ b/userspace/tiny.h
@@ -0,0 +1,4 @@
+#pragma once
+
+
+int func_tiny();