diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..73f7ffb
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,19 @@
+CC=gcc
+objects= stack.o method_dispatcher/method_dispatcher.o interpreter/core_methods.o interpreter/interpreter.o
+
+all: $(objects) test
+
+CFLAG= -c -O -o
+
+%.o: %.c
+	$(CC) $(CFLAG) $@ $<
+
+.PHONY: test
+
+test:
+	cd test && make
+	cd method_dispatcher/test && make
+	cd interpreter/test && make
+
+clean:
+	- rm $(objects)
diff --git a/base.h b/base.h
new file mode 100644
index 0000000..31c918f
--- /dev/null
+++ b/base.h
@@ -0,0 +1,20 @@
+#ifndef bci_base_h__
+#define bci_base_h__
+#include <inttypes.h>
+#include "stack.h"
+
+#define BCI_CORE_NUM_REG 40
+
+// Note that void * state will later be casted to
+// machine_state_t.
+typedef char (* bci_core_method_t)(uint8_t small_arg
+				, void * state);
+
+
+#define BCI_CORE_RESULT_RESERVED_BITS    0b11000000
+#define BCI_CORE_RESULT_APPLICATION_BITS 0b00111111
+
+#define BCI_CORE_SMALL_ARG_MASK 0b0000000000111111
+#define BCI_CORE_OPCODE_MASK    0b1111111111000000
+
+#endif
diff --git a/interpreter/core_methods.c b/interpreter/core_methods.c
new file mode 100644
index 0000000..b7c26a2
--- /dev/null
+++ b/interpreter/core_methods.c
@@ -0,0 +1,370 @@
+#include "core_methods.h"
+
+#define BCI_CORE_REGISTER_CHECK(var) if(var > BCI_CORE_NUM_REG) return 1
+
+// #1 -> $0
+char bci_cm_ldi(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	uint16_t arg;
+	char res;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	state->data_reg[small_arg] = arg;
+
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+// @($1) -> $0
+char bci_cm_ld(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	uint16_t arg;
+	char res;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	BCI_CORE_REGISTER_CHECK(arg);
+	arg = state->data_reg[arg];
+
+	res = machine_state_t_get_mem(state, arg, &arg);
+	if(res)
+	{
+		return res;
+	}
+	state->data_reg[small_arg] = arg;
+
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+// $0 -> @($1)
+char bci_cm_st(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	char res;
+
+	uint16_t arg;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	BCI_CORE_REGISTER_CHECK(arg);
+	arg = state->data_reg[arg];
+
+	res = machine_state_t_set_mem(state, arg, state->data_reg[small_arg]);
+	if(res)
+	{
+		return res;
+	}
+
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+// $0 + 1 -> $0
+char bci_cm_inc(uint8_t small_arg, machine_state_t state)
+{
+	int32_t result;
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	result = state->data_reg[small_arg] + 1;
+	state->data_reg[small_arg] = result & 0xffff;
+	state->status_reg = result >> 16;
+	return machine_state_t_default_afterexec(state, 0);
+}
+
+// $0 - 1 -> $0
+char bci_cm_dec(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	int32_t result = state->data_reg[small_arg] - 1;
+	state->data_reg[small_arg] = result & 0xffff;
+	state->status_reg = result >> 16;
+	return machine_state_t_default_afterexec(state, 0);
+}
+
+// $0 + $1 -> $0
+char bci_cm_add(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	uint16_t arg;
+	char res;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	BCI_CORE_REGISTER_CHECK(arg);
+	int32_t result = state->data_reg[small_arg] + state->data_reg[arg];
+	state->data_reg[small_arg] = result & 0xffff;
+	state->status_reg = result >> 16;
+	
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+
+// $0 - $1 -> $0
+char bci_cm_sub(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	uint16_t arg;
+	char res;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	BCI_CORE_REGISTER_CHECK(arg);
+	int32_t result = state->data_reg[small_arg] - state->data_reg[arg];
+	
+	state->data_reg[small_arg] = result & 0xffff;
+	state->status_reg = result >> 16;
+
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+
+// $0 * $1 -> $0
+char bci_cm_mul(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	uint16_t arg;
+	char res;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	BCI_CORE_REGISTER_CHECK(arg);
+	int32_t result = state->data_reg[small_arg] * state->data_reg[arg];
+	state->data_reg[small_arg] = result & 0xffff;
+	state->status_reg = result >> 16;
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+// $0 / $1 -> $0
+char bci_cm_div(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	uint16_t arg;
+	char res;
+	res = machine_state_t_get_word(state, state->program_counter + 1, &arg);
+	if(res)
+	{
+		return res;
+	}
+
+	BCI_CORE_REGISTER_CHECK(arg);
+	int32_t result = state->data_reg[small_arg] / state->data_reg[arg];
+	state->data_reg[small_arg] = result & 0xffff;
+	state->status_reg = result >> 16;
+	return machine_state_t_default_afterexec(state, 1);
+}
+
+
+// if($0 > 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_gt(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	if(state->data_reg[small_arg] > 0)
+	{
+		state->status_reg = 1;
+	}
+	else
+	{
+		state->status_reg = 0;
+	}
+	return machine_state_t_default_afterexec(state, 0);
+}
+
+// if($0 >= 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_ge(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	if(state->data_reg[small_arg] >= 0)
+	{
+		state->status_reg = 1;
+	}
+	else
+	{
+		state->status_reg = 0;
+	}
+	return machine_state_t_default_afterexec(state, 0);
+}
+// if($0 < 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_lt(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	if(state->data_reg[small_arg] < 0)
+	{
+		state->status_reg = 1;
+	}
+	else
+	{
+		state->status_reg = 0;
+	}
+	return machine_state_t_default_afterexec(state, 0);
+}
+// if($0 <= 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_le(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	if(state->data_reg[small_arg] <= 0)
+	{
+		state->status_reg = 1;
+	}
+	else
+	{
+		state->status_reg = 0;
+	}
+	return machine_state_t_default_afterexec(state, 0);
+}
+// if($0 == 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_eq(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+
+	if(state->data_reg[small_arg] == 0)
+	{
+		state->status_reg = 1;
+	}
+	else
+	{
+		state->status_reg = 0;
+	}
+	return machine_state_t_default_afterexec(state, 0);
+}
+
+// $0 -> $pc; 0 -> $st_reg
+char bci_cm_jmp(uint8_t small_arg, machine_state_t state)
+{
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	uint16_t arg = state->data_reg[arg];
+
+	state->status_reg = 0;
+	state->program_counter = arg;
+	return 0;
+}
+
+// if($st_reg): $0 -> $pc; 0 -> $st_reg
+// else: do nothing
+char bci_cm_cjmp(uint8_t small_arg, machine_state_t state)
+{
+	uint16_t arg = small_arg;
+	BCI_CORE_REGISTER_CHECK(small_arg);
+#ifdef DEBUG
+	printf("MSG: cjmp: arg=0x%x (=0x%x)\n", arg, state->data_reg[arg]);
+#endif
+	arg = state->data_reg[arg];
+
+	if(state->status_reg)
+	{
+		state->program_counter = arg;
+		state->status_reg = 0;
+		return 0;
+	}
+
+	return machine_state_t_default_afterexec(state, 0);
+}
+// $pc -> @stack
+// $0 -> $pc
+char bci_cm_call(uint8_t small_arg, machine_state_t state)
+{
+	uint16_t arg;
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	arg = state->data_reg[arg];
+
+	char res = bci_stack_t_push(&(state->stack), state->program_counter);
+	if(res)
+	{
+		return res;
+	}
+	state->program_counter = arg;
+	return 0;
+}
+// if($st_reg): $pc -> @stack; $0 -> $pc; 0 -> $st_reg
+// else: do nothing
+char bci_cm_ccall(uint8_t small_arg, machine_state_t state)
+{
+	uint16_t arg;
+	char res;
+	BCI_CORE_REGISTER_CHECK(small_arg);
+	arg = state->data_reg[small_arg];
+
+	if(state->status_reg)
+	{
+		state->program_counter = arg;
+		res = bci_stack_t_push(&(state->stack), state->program_counter);
+		if(res)
+		{
+			return res;
+		}
+		return 0;
+	}
+
+	state->status_reg = 0;
+	return machine_state_t_default_afterexec(state, 0);
+}
+// @stack -> $pc
+char bci_cm_ret(uint8_t small_arg, machine_state_t state)
+{
+	uint16_t result;
+	char res = bci_stack_t_pop(&(state->stack), &result);
+	if(res)
+	{
+		return res;
+	}
+
+	state->program_counter = result;
+	return 0;
+}
+
+// 0 -> $st_reg
+char bci_cm_cl(uint8_t small_arg, machine_state_t state)
+{
+	state->status_reg = 0;
+	return machine_state_t_default_afterexec(state, 0);
+}
+
+// 1 -> $su_reg
+char bci_cm_stop(uint8_t small_arg, machine_state_t state)
+{
+	state->shutdown_reg = 1;
+	return machine_state_t_default_afterexec(state, 0);
+}
+
+// if($st_reg): 0 -> $st_reg
+// else: 1 -> $st_reg
+char bci_cm_not(uint8_t small_arg, machine_state_t state)
+{
+	if(state->status_reg)
+	{
+		state->status_reg = 0;
+	}
+	else
+	{
+		state->status_reg = 1;
+	}
+	return machine_state_t_default_afterexec(state, 0);
+}
diff --git a/interpreter/core_methods.h b/interpreter/core_methods.h
new file mode 100644
index 0000000..e36892a
--- /dev/null
+++ b/interpreter/core_methods.h
@@ -0,0 +1,114 @@
+#ifndef bci_core_methods_h__
+#define bci_core_methods_h__
+#include "interpreter.h"
+
+
+/*
+ * This library brings a set of essential core methods.
+ * */
+
+
+/*
+ * Naming conventions:
+ *
+ * x = 0, 1, 2, 3...: arguments.
+ *     0: small_arg (6 bit)
+ *     1, 2, ...: 16 bit optional arguments
+ *
+ * $x: value of data register x
+ * @x: value of memory word x
+ * #x: value of argument x
+ * 0, 1, 2, ...: integer 0, 1, 2, ...
+ *
+ * -> write result in register/word on the right
+ *
+ * st_reg: status register
+ * su_reg: shutdown register
+ * pc: program counter
+ *
+ * stack: the builtin stack
+ * */
+
+// #1 -> $0
+char bci_cm_ldi(uint8_t small_arg, machine_state_t state);
+
+// @($1) -> $0
+char bci_cm_ld(uint8_t small_arg, machine_state_t state);
+
+// $0 -> @($1)
+char bci_cm_st(uint8_t small_arg, machine_state_t state);
+
+
+// NOTES on inc, dec, add, sub, mul, div:
+//
+// These methods will store the overflow-word in $st_reg.
+
+
+// $0 + 1 -> $0
+char bci_cm_inc(uint8_t small_arg, machine_state_t state);
+
+// $0 - 1 -> $0
+char bci_cm_dec(uint8_t small_arg, machine_state_t state);
+
+// $0 + $1 -> $0
+char bci_cm_add(uint8_t small_arg, machine_state_t state);
+
+// $0 - $1 -> $0
+char bci_cm_sub(uint8_t small_arg, machine_state_t state);
+
+// $0 * $1 -> $0
+char bci_cm_mul(uint8_t small_arg, machine_state_t state);
+
+// $0 / $1 -> $0
+char bci_cm_div(uint8_t small_arg, machine_state_t state);
+
+// if($0 > 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_gt(uint8_t small_arg, machine_state_t state);
+
+// if($0 >= 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_ge(uint8_t small_arg, machine_state_t state);
+
+// if($0 < 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_lt(uint8_t small_arg, machine_state_t state);
+
+// if($0 <= 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_le(uint8_t small_arg, machine_state_t state);
+
+// if($0 == 0): 1 -> $st_reg
+// else: 0 -> $st_reg
+char bci_cm_eq(uint8_t small_arg, machine_state_t state);
+
+// if($st_reg): 0 -> $st_reg
+// else: 1 -> $st_reg
+char bci_cm_not(uint8_t small_arg, machine_state_t state);
+
+// $1 -> $pc
+char bci_cm_jmp(uint8_t small_arg, machine_state_t state);
+
+// if($st_reg): $1 -> $pc
+// else: do nothing
+char bci_cm_cjmp(uint8_t small_arg, machine_state_t state);
+
+// $pc -> @stack
+// $0 -> $pc
+char bci_cm_call(uint8_t small_arg, machine_state_t state);
+
+// if($st_reg): $pc -> @stack; $0 -> $pc
+// else: do nothing
+char bci_cm_ccall(uint8_t small_arg, machine_state_t state);
+
+// @stack -> $pc
+char bci_cm_ret(uint8_t small_arg, machine_state_t state);
+
+// 0 -> $st_reg
+char bci_cm_cl(uint8_t small_arg, machine_state_t state);
+
+// 1 -> $su_reg
+char bci_cm_stop(uint8_t small_arg, machine_state_t state);
+
+
+#endif
diff --git a/interpreter/interpreter.c b/interpreter/interpreter.c
new file mode 100644
index 0000000..4089fdd
--- /dev/null
+++ b/interpreter/interpreter.c
@@ -0,0 +1,217 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "interpreter.h"
+
+
+
+machine_state_t machine_state_t_new( void * cache_function_data
+				, size_t program_size
+				, size_t cache_size
+				, size_t memory_size
+				, size_t (* cache_block)(uint16_t * cache
+							, uint16_t offset
+							, size_t cache_size
+							, void * cache_function_data)
+				, dispatch_tree_t method_dispatcher)
+{
+
+	machine_state_t state = malloc(sizeof(struct machine_state_s));
+	if(!state)
+	{
+		return NULL;
+	}
+	uint16_t * cache = calloc(sizeof(uint16_t), cache_size);
+	if(!cache)
+	{
+		free(state);
+		return NULL;
+	}
+	uint16_t * memory = calloc(sizeof(uint16_t), memory_size);
+	if(!memory)
+	{
+		free(state);
+		free(cache);
+		return NULL;
+	}
+
+
+	state->program_size = program_size;
+	state->cache = cache;
+	state->cache_block = cache_block;
+	state->cache_size = cache_size;
+	state->cache_loaded = 0;
+	state->cache_offset = 0;
+	state->cache_function_data = cache_function_data;
+
+	state->program_counter = 0;
+	state->status_reg = 0;
+	state->shutdown_reg = 0;
+	int i;
+	for(i = 0; i < BCI_CORE_NUM_REG; i++)
+	{
+		state->data_reg[i] = 0;
+	}
+	state->stack = NULL;
+
+	state->memory = memory;
+	state->memory_size = memory_size;
+
+	state->method_dispatcher = method_dispatcher;
+
+	return state;
+}
+
+void machine_state_t_del(machine_state_t state)
+{
+	free(state->cache);
+	free(state->memory);
+	dispatch_tree_t_del(state->method_dispatcher);
+	bci_stack_t_del(&(state->stack));
+	free(state);
+}
+
+
+char update_cache(machine_state_t state, uint16_t offset)
+{
+	// Calculate a clever offset for caching.
+	uint16_t cache_offset = offset;
+	if((cache_offset + state->cache_size)
+		> state->program_size)
+	{
+		if(state->program_size < state->cache_size)
+		{
+			cache_offset = 0;
+		}
+		else
+		{
+			cache_offset = state->program_size - state->cache_size;
+		}
+	}
+	size_t cached = state->cache_block(state->cache
+					, cache_offset
+					, state->cache_size
+					, state->cache_function_data);
+
+	if(cached != state->cache_size)
+	{
+		#ifdef DEBUG
+		printf("ERROR: should have cached %zu words, but got %zu.\n", state->cache_size, cached);
+		#endif
+		return 1;
+	}
+	state->cache_offset = cache_offset;
+	state->cache_loaded = 1;
+	return 0;
+}
+
+char machine_state_t_get_word(machine_state_t state, uint16_t offset, uint16_t * result)
+{
+
+	// This would be bad.
+	if(offset >= state->program_size)
+	{
+		return 0b01000000 | 1; 
+	}
+	
+	// Calculate the in-cache offset of the desired offset.
+	int32_t in_cache_offset = offset - state->cache_offset;
+
+	// Check if we need to update the cache.
+	if( in_cache_offset < 0
+		|| !(state->cache_loaded)
+		)
+	{
+		if(update_cache(state, offset))
+		{
+			#ifdef DEBUG
+			printf("ERROR: failed to update cache\n");
+			#endif
+			state->error = 0b01000000 | 2;
+			return 0b01000000 | 2;
+		}
+		// Re-calculate the in-cache offset
+		in_cache_offset = offset - state->cache_offset;
+	}
+
+	*result = state->cache[in_cache_offset];
+	return 0;
+
+}
+
+char machine_state_t_exec_cycle(machine_state_t state)
+{
+	char res = 0;
+	uint16_t opcode;
+	res = machine_state_t_get_word(state, state->program_counter, &opcode);
+	
+	if(res)
+	{
+		return res;
+	}
+
+#ifdef DEBUG
+	printf("MSG: opcode = 0x%x, small_arg = 0x%x\n"
+			, opcode & BCI_CORE_OPCODE_MASK
+			, opcode & BCI_CORE_SMALL_ARG_MASK);
+#endif
+
+	bci_core_method_t method = dispatch_tree_t_dispatch(
+					state->method_dispatcher
+					, opcode & BCI_CORE_OPCODE_MASK);
+	if(!method)
+	{
+		state->error = res;
+		return 0b10000000 | 1;
+	}
+
+	return BCI_CORE_RESULT_APPLICATION_BITS 
+		& method( opcode & BCI_CORE_SMALL_ARG_MASK
+			, state);
+
+}
+
+
+char machine_state_t_default_afterexec(machine_state_t state, uint8_t argc)
+{
+	state->program_counter += 1 + argc;
+	return 0;
+}
+
+
+char machine_state_t_get_mem(machine_state_t state, uint16_t offset, uint16_t * result)
+{
+	if(offset > state->memory_size)
+	{
+		state->error = 0b01000000 | 15;
+		return 0b01000000 | 15;
+	}
+
+	*result = state->memory[offset];
+	return 0;
+}
+char machine_state_t_set_mem(machine_state_t state, uint16_t offset, uint16_t data)
+{
+	if(offset > state->memory_size)
+	{
+		state->error = 0b01000000 | 15;
+		return 0b01000000 | 15;
+	}
+
+	state->memory[offset] = data;
+	return 0;
+}
+
+
+
+
+char machine_state_t_exec(machine_state_t state)
+{
+	char status = 0;
+	while((!status) && (!state->shutdown_reg))
+	{
+		status = machine_state_t_exec_cycle(state);
+	}
+	state->error = status;
+	return status;
+}
diff --git a/interpreter/interpreter.h b/interpreter/interpreter.h
new file mode 100644
index 0000000..4829148
--- /dev/null
+++ b/interpreter/interpreter.h
@@ -0,0 +1,121 @@
+#ifndef bci_interpreter_h__
+#define bci_interpreter_h__
+
+#include <stddef.h>
+#include "../base.h"
+#include "../method_dispatcher/method_dispatcher.h"
+#include "../stack.h"
+
+typedef struct machine_state_s
+{
+	// The size of the program in 16-bit words
+	uint16_t program_size; 
+	void * cache_function_data;
+
+	size_t cache_size;
+	uint16_t cache_offset;
+	uint16_t * cache;
+	size_t (* cache_block)(uint16_t * cache
+				, uint16_t offset
+				, size_t cache_size
+				, void * cache_function_data);
+	char cache_loaded;
+
+	uint16_t program_counter;
+	uint16_t status_reg;
+	// Any non-zero value in this register will
+	// break the program execution.
+	uint16_t shutdown_reg;
+	uint16_t data_reg[BCI_CORE_NUM_REG];
+	bci_stack_t stack;
+
+	size_t memory_size;
+	uint16_t * memory;
+
+
+	dispatch_tree_t method_dispatcher;
+
+	// Possible Error Codes:
+	// 0b01xxxxxx: memory related internal error 
+	// 0b10xxxxxx: core method related internal error
+	// 0b00xxxxxx: application related internal error
+	//
+	//
+	// 0b01000000 | 1: Program offset out of bounds
+	// 0b01000000 | 2: Failed to cache new data
+	// 0b01000000 | 15: Memory offset out of bounds
+	//
+	//
+	// 0b10000000 | 1: Unknown opcode
+	char error;
+
+} * machine_state_t;
+
+machine_state_t machine_state_t_new( void * cache_function_data
+				, size_t program_size
+				, size_t cache_size
+				, size_t memory_size
+				, size_t (* cache_block)(uint16_t * cache
+							, uint16_t offset
+							, size_t cache_size
+							, void * cache_function_data)
+				, dispatch_tree_t method_dispatcher);
+
+void machine_state_t_del(machine_state_t state);
+
+/*
+ * This function essentially executes one cycle of the machine execution.
+ * It will fetch the opcode and argument, dispatch the method and execute it.
+ *
+ * Also this will update the cache if needed.
+ *
+ * Possible return codes:
+ *
+ * - 0bxyXXXXXX
+ *   Error while executing the cycle.
+ *   - 0b01XXXXXX
+ *     Error in the internal memory management (i.e. program counter out
+ *     of bounds)
+ *     - 0b01000000 | 1: program_counter  or argument offset > program_size
+ *     - 0b01000000 | 2: failed to cache new data
+ *
+ *   - 0b10XXXXXX
+ *     Error while dispatching the method
+ *     - 0b10000000 | 1: unknown opcode
+ *
+ * - 0b00XXXXXX
+ *   XXXXXX is the return value of the bci_core_method_t method.
+ * */
+char machine_state_t_exec_cycle(machine_state_t state);
+
+
+/*
+ * Runs ``machine_state_t_exec_cycle`` until either this function
+ * returns a non-zero value or a non-zero value is stored in
+ * ``state->shutdown_reg``. 
+ * Sets ``state->error`` to the last return value of ``machine_state_t_exec_cycle``
+ * and returns it.
+ * */
+char machine_state_t_exec(machine_state_t state);
+
+/*
+ * Do the default updates on the machine state.
+ * This will be basically increasing the program counter.
+ * */
+char machine_state_t_default_afterexec(machine_state_t state, uint8_t argc);
+
+/*
+ * Get the word at offset in the program memory.
+ * Returns 0 on success, a non-zero value otherwise.
+ *
+ * It will set state->error appropiately.
+ * */
+char machine_state_t_get_word(machine_state_t state, uint16_t offset, uint16_t * result);
+
+/*
+ * Get the word at offset in the RAM-alike memory.
+ * Works like machine_state_t_get_word.
+ * */
+char machine_state_t_get_mem(machine_state_t state, uint16_t offset, uint16_t * result);
+char machine_state_t_set_mem(machine_state_t state, uint16_t offset, uint16_t data);
+#endif
diff --git a/interpreter/test/Makefile b/interpreter/test/Makefile
new file mode 100644
index 0000000..6703b38
--- /dev/null
+++ b/interpreter/test/Makefile
@@ -0,0 +1,14 @@
+CC=gcc
+
+all: test_interpreter
+
+interpreter: clean
+	$(CC) -g ../../stack.c ../interpreter.c ../core_methods.c ../../method_dispatcher/method_dispatcher.c test_interpreter.c -o interpreter
+
+test_interpreter: interpreter
+	valgrind ./interpreter
+
+
+
+clean:
+
diff --git a/interpreter/test/test_interpreter.c b/interpreter/test/test_interpreter.c
new file mode 100644
index 0000000..62db833
--- /dev/null
+++ b/interpreter/test/test_interpreter.c
@@ -0,0 +1,69 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include "../interpreter.h"
+#include "../core_methods.h"
+#include "../../method_dispatcher/method_dispatcher.h"
+
+size_t copy_cache(uint16_t * cache
+		, uint16_t offset
+		, size_t cache_size
+		, void * cache_function_data);
+
+int main(void)
+{
+	dispatch_tree_t tree = dispatch_tree_t_new();
+	dispatch_tree_autoinserter_t inserter = dispatch_tree_autoinserter_t_new(tree);
+	uint16_t ldi = dispatch_tree_autoinserter_t_insert(inserter, (bci_core_method_t) bci_cm_ldi);
+	uint16_t add = dispatch_tree_autoinserter_t_insert(inserter, (bci_core_method_t) bci_cm_add);
+
+	uint16_t * program = calloc(sizeof(uint16_t), 20);
+	program[0] = ldi;
+	program[1] = 0xfefe;
+	program[2] = ldi | 1;
+	program[3] = 2;
+	program[4] = ldi | 2;
+	program[5] = 3;
+	program[6] = add | 1;
+	program[7] = 2;
+
+	machine_state_t state = machine_state_t_new(
+			program
+			, 8
+			, 20
+			, 20
+			, copy_cache
+			, tree);
+
+	machine_state_t_exec_cycle(state);
+	machine_state_t_exec_cycle(state);
+	machine_state_t_exec_cycle(state);
+	machine_state_t_exec_cycle(state);
+	printf("data_reg[0]: %x\n", state->data_reg[0]);
+	assert(state->data_reg[0] == 0xfefe);
+	printf("data_reg[1]: %x\n", state->data_reg[1]);
+	assert(state->data_reg[1] == 5);
+	printf("data_reg[2]: %x\n", state->data_reg[2]);
+	assert(state->data_reg[2] == 3);
+	printf("program_counter: %d\n", state->program_counter);
+	assert(state->program_counter == 8);
+	dispatch_tree_autoinserter_t_del(inserter);
+	machine_state_t_del(state);
+	free(program);
+	return 0;
+}
+
+size_t copy_cache(uint16_t * cache
+		, uint16_t offset
+		, size_t cache_size
+		, void * cache_function_data)
+{
+	size_t i;
+	for(i = 0; i < cache_size; i++)
+	{
+		printf("\tCP [%zd]->[%zd]: %x\n", i + offset, i, ((uint16_t *) cache_function_data)[i + offset]);
+		cache[i] = ((uint16_t *) cache_function_data)[i + offset];
+	}
+	return i;
+}
+
diff --git a/method_dispatcher/method_dispatcher.c b/method_dispatcher/method_dispatcher.c
new file mode 100644
index 0000000..e26c553
--- /dev/null
+++ b/method_dispatcher/method_dispatcher.c
@@ -0,0 +1,158 @@
+#include <stdlib.h>
+#include "method_dispatcher.h"
+
+
+dispatch_tree_t dispatch_tree_t_new(void)
+{
+	dispatch_tree_t tree = malloc(sizeof(struct dispatch_tree_s));
+	tree->root = NULL;
+	return tree;
+}
+
+void dispatch_tree_t_del(dispatch_tree_t tree)
+{
+	dispatch_tree_node_t_del(tree->root);
+	free(tree);
+}
+
+dispatch_tree_node_t dispatch_tree_node_t_new(uint16_t word
+					, bci_core_method_t method)
+{
+	dispatch_tree_node_t node = malloc(sizeof(struct dispatch_tree_node_s));
+	node->higher = NULL;
+	node->lower = 0;
+	node->method = method;
+	node->word = word;
+	return node;
+}
+
+void dispatch_tree_node_t_del(dispatch_tree_node_t node)
+{
+	if(node->higher)
+	{
+		dispatch_tree_node_t_del(node->higher);
+	}
+	if(node->lower)
+	{
+		dispatch_tree_node_t_del(node->lower);
+	}
+	free(node);
+}
+
+char dispatch_tree_t_insert(dispatch_tree_t tree
+			, uint16_t word
+			, bci_core_method_t method)
+{
+	dispatch_tree_node_t new_node = dispatch_tree_node_t_new(word, method);
+	if(!new_node)
+	{
+		return 1;
+	}
+	// explicitly handle empty tree
+	if(!tree->root)
+	{
+		tree->root = new_node;
+		return 0;
+	}
+
+	// non-empty tree
+	dispatch_tree_node_t this_node = tree->root;
+	dispatch_tree_node_t parent_node = NULL;
+	// search for place
+	do
+	{
+		parent_node = this_node;
+		if(parent_node->word < word)
+		{
+			this_node = parent_node->higher;
+			continue;
+		}
+		if(parent_node->word > word)
+		{
+			this_node = parent_node->lower;
+			continue;
+		}
+		if(parent_node->word == word)
+		{
+			// we already have that key.
+			return 2;
+		}
+
+	} 
+	while(this_node);
+	if(parent_node->word < word)
+	{
+		parent_node->higher = new_node;
+	}
+	if(parent_node->word > word)
+	{
+		parent_node->lower = new_node;
+	}
+
+	return 0;
+
+}
+
+
+bci_core_method_t dispatch_tree_t_dispatch(dispatch_tree_t tree
+					, uint16_t word)
+{
+	dispatch_tree_node_t this_node = tree->root;
+	while(this_node)
+	{
+		if(this_node->word < word)
+		{
+			this_node = this_node->higher;
+			continue;
+		}
+		if(this_node->word > word)
+		{
+			this_node = this_node->lower;
+			continue;
+		}
+		if(this_node->word == word)
+		{
+			return this_node->method;
+		}
+	}
+	return NULL;
+}
+	
+dispatch_tree_autoinserter_t dispatch_tree_autoinserter_t_new(dispatch_tree_t tree)
+{
+	dispatch_tree_autoinserter_t autoinserter = malloc(
+			sizeof(struct dispatch_tree_autoinserter_s));
+	if(!autoinserter)
+	{
+		return NULL;
+	}
+	autoinserter->mayor = 2;
+	autoinserter->minor = 1;
+	autoinserter->tree = tree;
+	return autoinserter;
+}
+
+void dispatch_tree_autoinserter_t_del(dispatch_tree_autoinserter_t autoinserter)
+{
+	free(autoinserter);
+}
+
+
+uint16_t dispatch_tree_autoinserter_t_insert(
+			dispatch_tree_autoinserter_t autoinserter
+			, bci_core_method_t method)
+{
+	uint16_t opcode = 0b1111111111;
+	opcode *= autoinserter->minor;
+	opcode /= autoinserter->mayor;
+	opcode <<= 6;
+
+	dispatch_tree_t_insert(autoinserter->tree, opcode, method);
+
+	autoinserter->minor = (autoinserter->minor + 2) % autoinserter->mayor;
+	if(autoinserter->minor == 1)
+	{
+		autoinserter->mayor *= 2;
+	}
+	return opcode;
+}
diff --git a/method_dispatcher/method_dispatcher.h b/method_dispatcher/method_dispatcher.h
new file mode 100644
index 0000000..6b6dac9
--- /dev/null
+++ b/method_dispatcher/method_dispatcher.h
@@ -0,0 +1,87 @@
+#ifndef bci_method_dispatcher_h__
+#define bci_method_dispatcher_h__
+
+#include <inttypes.h>
+#include "../base.h"
+
+typedef struct dispatch_tree_node_s
+{
+	struct dispatch_tree_node_s * higher;
+	struct dispatch_tree_node_s * lower;
+	uint16_t word;
+	bci_core_method_t method;
+} * dispatch_tree_node_t;
+
+typedef struct dispatch_tree_s
+{
+	dispatch_tree_node_t root;
+} * dispatch_tree_t;
+
+dispatch_tree_t dispatch_tree_t_new(void);
+/*
+ * This deletes the tree and will invoke dispatch_tree_node_t_del on 
+ * tree->root (which will delete all the other nodes recursively). 
+ * If you want to keep nodes you have to explicityl remove the reference to
+ * them by setting them to NULL.
+ * */
+void dispatch_tree_t_del(dispatch_tree_t tree);
+
+
+dispatch_tree_node_t dispatch_tree_node_t_new(uint16_t word
+				, bci_core_method_t method);
+/*
+ * This deletes the node an will invoke dispatch_tree_node_t_del on
+ * node->higher and node->lower. If you want to keep those nodes 
+ * you have to explicitly clear the reference by setting them to NULL.
+ * */
+void dispatch_tree_node_t_del(dispatch_tree_node_t node);
+
+
+/*
+ * Insert a new key-value-pair into the tree.
+ *
+ * Return codes:
+ * 0: OK
+ * 1: out of memory
+ * 2: key already in tree
+ * */
+char dispatch_tree_t_insert(dispatch_tree_t tree
+			, uint16_t word
+			, bci_core_method_t method);
+
+
+bci_core_method_t dispatch_tree_t_dispatch(dispatch_tree_t tree
+					, uint16_t word);
+
+
+
+typedef struct dispatch_tree_autoinserter_s
+{
+	uint16_t mayor;
+	uint16_t minor;
+	dispatch_tree_t tree;
+} * dispatch_tree_autoinserter_t;
+
+dispatch_tree_autoinserter_t dispatch_tree_autoinserter_t_new(dispatch_tree_t tree);
+void dispatch_tree_autoinserter_t_del(dispatch_tree_autoinserter_t autoinserter);
+
+/*
+ * This function inserts a new method into the tree and automatically 
+ * chooses the optimal word to prevent degeneration.
+ *
+ * NOTE:
+ * When inserting mutliple methods this function acts deterministic,
+ * IF AND ONLY IF the order of the methods is not changed.
+ *
+ * The assembler will bring an analogous function that allows one 
+ * to determine the opcodes of the methods.
+ *
+ * NOTE:
+ * This algorithm will not work for more that 1023 registered opcodes.
+ * This limit is however considered acceptable.
+ *
+ * */
+uint16_t dispatch_tree_autoinserter_t_insert(
+			dispatch_tree_autoinserter_t autoinserter
+			, bci_core_method_t method);
+#endif
diff --git a/method_dispatcher/test/Makefile b/method_dispatcher/test/Makefile
new file mode 100644
index 0000000..c9fc7c9
--- /dev/null
+++ b/method_dispatcher/test/Makefile
@@ -0,0 +1,14 @@
+CC=gcc
+
+all: test_method_dispatcher
+
+method_dispatcher: clean
+	$(CC) -g ../method_dispatcher.c test_method_dispatcher.c -o method_dispatcher
+
+test_method_dispatcher: method_dispatcher
+	valgrind ./method_dispatcher
+
+
+
+clean:
+	-rm method_dispatcher
diff --git a/method_dispatcher/test/test_method_dispatcher.c b/method_dispatcher/test/test_method_dispatcher.c
new file mode 100644
index 0000000..917e901
--- /dev/null
+++ b/method_dispatcher/test/test_method_dispatcher.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include "../method_dispatcher.h"
+
+char m1(uint8_t small_arg, void * state);
+char m2(uint8_t small_arg, void * state);
+char m3(uint8_t small_arg, void * state);
+char m4(uint8_t small_arg, void * state);
+char m5(uint8_t small_arg, void * state);
+
+int main(void)
+{
+	printf("sizeof struct dispatch_tree_node_s: %zd\n", sizeof(struct dispatch_tree_node_s));
+	dispatch_tree_t tree = dispatch_tree_t_new();
+
+	dispatch_tree_t_insert(tree, 3 << 6, m3);
+	dispatch_tree_t_insert(tree, 2 << 6, m2);
+	dispatch_tree_t_insert(tree, 1 << 6, m1);
+	dispatch_tree_t_insert(tree, 4 << 6, m4);
+	dispatch_tree_t_insert(tree, 5 << 6, m5);
+
+	int i;
+	for(i = 1; i < 6; i++)
+	{
+		dispatch_tree_t_dispatch(tree, i << 6)(i, NULL);
+	}
+	dispatch_tree_t_del(tree);
+
+
+	bci_core_method_t methods[5] = {m1, m2, m3, m4, m5};
+	tree = dispatch_tree_t_new();
+	dispatch_tree_autoinserter_t inserter = dispatch_tree_autoinserter_t_new(tree);
+	for(i = 0; i < 5; i++)
+	{
+		printf("%u\n", dispatch_tree_autoinserter_t_insert(inserter, methods[i]));
+	}
+	dispatch_tree_autoinserter_t_del(inserter);
+	dispatch_tree_t_del(tree);
+
+	return 0;
+}
+
+
+
+char m1(uint8_t small_arg, void * state)
+{
+	printf("m1: %d\n", small_arg);
+}
+char m2(uint8_t small_arg, void * state)
+{
+	printf("m2: %d\n", small_arg);
+}
+char m3(uint8_t small_arg, void * state)
+{
+	printf("m3: %d\n", small_arg);
+}
+char m4(uint8_t small_arg, void * state)
+{
+	printf("m4: %d\n", small_arg);
+}
+char m5(uint8_t small_arg, void * state)
+{
+	printf("m5: %d\n", small_arg);
+}
diff --git a/stack.c b/stack.c
new file mode 100644
index 0000000..97d4a8c
--- /dev/null
+++ b/stack.c
@@ -0,0 +1,40 @@
+#include <stdlib.h>
+#include "stack.h"
+
+char bci_stack_t_push(bci_stack_t * stack, uint16_t value)
+{
+	bci_stack_t node = malloc(sizeof(struct bci_stack_s));
+	if(!node)
+	{
+		return 1;
+	}
+	node->next = *stack;
+	node->value = value;
+	*stack = node;
+	return 0;
+}
+char bci_stack_t_pop(bci_stack_t * stack, uint16_t * result)
+{
+	bci_stack_t this_node;
+	if(!*stack)
+	{
+		return 1;
+	}
+	this_node = *stack;
+	*result = this_node->value;
+	*stack = this_node->next;
+	free(this_node);
+	return 0;
+}
+
+void bci_stack_t_del(bci_stack_t * stack)
+{
+	bci_stack_t this_node;
+
+	while(*stack)
+	{
+		this_node = *stack;
+		*stack = this_node->next;
+		free(this_node);
+	}
+}
diff --git a/stack.h b/stack.h
new file mode 100644
index 0000000..0522db0
--- /dev/null
+++ b/stack.h
@@ -0,0 +1,20 @@
+#ifndef bci_stack_h__
+#define bci_stack_h__
+
+#include <inttypes.h>
+
+typedef struct bci_stack_s
+{
+	struct bci_stack_s * next;
+	uint16_t value;
+} * bci_stack_t;
+
+char bci_stack_t_push(bci_stack_t * stack, uint16_t value);
+char bci_stack_t_pop(bci_stack_t * stack, uint16_t * result);
+
+/*
+ * Deletes the entire (!) stack.
+ *
+ * */
+void bci_stack_t_del(bci_stack_t * stack);
+#endif
diff --git a/test/Makefile b/test/Makefile
new file mode 100644
index 0000000..a90518d
--- /dev/null
+++ b/test/Makefile
@@ -0,0 +1,12 @@
+CC=gcc
+
+all: test_stack
+
+stack: clean
+	$(CC) -g ../stack.c test_stack.c -o stack
+
+test_stack: stack
+	valgrind ./stack
+
+clean:
+	-rm stack
diff --git a/test/test_stack.c b/test/test_stack.c
new file mode 100644
index 0000000..328c35c
--- /dev/null
+++ b/test/test_stack.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include "../stack.h"
+#include <assert.h>
+
+int main(void)
+{
+	bci_stack_t stack = NULL;
+	int i;
+	uint16_t res;
+	char status = 0;
+
+
+	for(i = 0; i < 10; i++)
+	{
+		bci_stack_t_push(&stack, (uint16_t) i);
+	}
+	--i;
+	while(!status)
+	{
+		status = bci_stack_t_pop(&stack, &res);
+		if(!status)
+		{
+			assert(res == i--);
+		}
+	}
+
+
+	for(i = 0; i < 10; i++)
+	{
+		bci_stack_t_push(&stack, (uint16_t) i);
+	}
+	bci_stack_t_del(&stack);
+	return 0;
+}