diff --git a/makefile b/makefile
index c309a6f..623c3af 100644
--- a/makefile
+++ b/makefile
@@ -26,16 +26,13 @@ ifdef DEBUG
 	MODE   = debug
 endif
 
-.PHONY: all clean test
+.PHONY: all clean test test-all test-z80 test-asm test-dasm
 
 all: $(BNRY)
 
 clean:
 	$(RM) $(BUILD) $(PROGRAM) $(PROGRAM)$(DEVEXT)
 
-test:
-	@echo "not implemented yet"
-
 $(DIRS):
 	$(MKDIR) $@
 
@@ -48,3 +45,17 @@ $(BUILD)/$(MODE)/%.o: %.c
 	$(CC) $(FLAGS) $(CFLAGS) -MMD -MP -c $< -o $@
 
 -include $(DEPS)
+
+test: test-all test-z80 test-asm test-dasm
+
+test-all:
+	@echo "running all tests"
+
+test-z80:
+	@echo "running Z80 CPU tests"
+
+test-asm:
+	@echo "running assembler tests"
+
+test-dasm:
+	@echo "running disassembler tests"
diff --git a/tests/01_basic_math.asm b/tests/01_basic_math.asm
new file mode 100644
index 0000000..7a46b58
--- /dev/null
+++ b/tests/01_basic_math.asm
@@ -0,0 +1,47 @@
+;; Copyright (C) 2014-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
+;; Released under the terms of the MIT License. See LICENSE for details.
+
+; ----- CRATER UNIT TESTING SUITE ---------------------------------------------
+
+; This file contains test cases for basic arithmetic operations on registers,
+; without involving memory or control flow.
+
+.include	"_header.asm"
+
+test:
+	ld	a, 0
+	ld	b, 0
+	ld	c, 0
+	ld	d, 0
+	ld	e, 0
+	ld	h, 0
+	ld	l, 0
+	emu	rassert(a=$00, b=$00, c=$00, d=$00, e=$00, h=$00, l=$00)
+
+	inc	a
+	emu	rassert(a=$01, b=$00, c=$00, d=$00, e=$00, h=$00, l=$00)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
+
+	inc	b
+	emu	rassert(a=$01, b=$01, c=$00, d=$00, e=$00, h=$00, l=$00)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
+
+	inc	c
+	emu	rassert(a=$01, b=$01, c=$01, d=$00, e=$00, h=$00, l=$00)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
+
+	inc	d
+	emu	rassert(a=$01, b=$01, c=$01, d=$01, e=$00, h=$00, l=$00)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
+
+	inc	e
+	emu	rassert(a=$01, b=$01, c=$01, d=$01, e=$01, h=$00, l=$00)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
+
+	inc	h
+	emu	rassert(a=$01, b=$01, c=$01, d=$01, e=$01, h=$01, l=$00)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
+
+	inc	l
+	emu	rassert(a=$01, b=$01, c=$01, d=$01, e=$01, h=$01, l=$01)
+	emu	fassert(s=0, z=0, f5=0, h=0, f3=0, pv=0, n=0)
diff --git a/tests/_header.asm b/tests/_header.asm
new file mode 100644
index 0000000..c4f3036
--- /dev/null
+++ b/tests/_header.asm
@@ -0,0 +1,30 @@
+;; Copyright (C) 2014-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
+;; Released under the terms of the MIT License. See LICENSE for details.
+
+; ----- CRATER UNIT TESTING SUITE ---------------------------------------------
+
+; This file contains basic header code for standard assembly files in the unit
+; testing suite. It sets values for the ROM header, and contains basic test
+; runner code.
+
+.optimizer	off		; Generate faithful rather than fast code
+
+.rom_size	auto		; Smallest possible ROM size >= 32 KB
+.rom_header	auto		; Standard header location (0x7FF0)
+.rom_checksum	off		; Don't write a ROM checksum to the header
+.rom_product	0		; Zero product code
+.rom_version	0		; Zero version number
+.rom_region	"GG Export"	; Common region code for Western ROMs
+.rom_declsize	auto		; Set declared size to actual ROM size
+
+; Main routine (execution begins here)
+.org $0000
+main:
+	di			; Disable maskable interrupts
+	call	test		; Run test subroutine
+	emu	except(done)	; Signal to emulator that test is done
+
+; Non-maskable interrupt handler (should not happen; raise an exception)
+.org $0066
+nmi_handler:
+	emu	except(nmi)	; Signal to emulator that an NMI was received
diff --git a/tests/runner.c b/tests/runner.c
new file mode 100644
index 0000000..1763ea4
--- /dev/null
+++ b/tests/runner.c
@@ -0,0 +1,4 @@
+/* Copyright (C) 2014-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
+   Released under the terms of the MIT License. See LICENSE for details. */
+
+// ...