diff --git a/parts/z80/core.asm b/parts/z80/core.asm
index 5a2473e..e71f3bc 100644
--- a/parts/z80/core.asm
+++ b/parts/z80/core.asm
@@ -167,70 +167,6 @@ fmtHexPair:
 	pop	af
 	ret
 
-; Parse the hex char at A and extract it's 0-15 numerical value. Put the result
-; in A.
-;
-; On success, the carry flag is reset. On error, it is set.
-parseHex:
-	; First, let's see if we have an easy 0-9 case
-	cp	'0'
-	jr	c, .error	; if < '0', we have a problem
-	cp	'9'+1
-	jr	nc, .alpha	; if >= '9'+1, we might have alpha
-	; We are in the 0-9 range
-	sub	'0'		; C is clear
-	ret
-
-.alpha:
-	call	upcase
-	cp	'A'
-	jr	c, .error	; if < 'A', we have a problem
-	cp	'F'+1
-	jr	nc, .error	; if >= 'F', we have a problem
-	; We have alpha.
-	sub	'A'-10		; C is clear
-	ret
-
-.error:
-	scf
-	ret
-
-; Parses 2 characters of the string pointed to by HL and returns the numerical
-; value in A. If the second character is a "special" character (<0x21) we don't
-; error out: the result will be the one from the first char only.
-; HL is set to point to the last char of the pair.
-;
-; On success, the carry flag is reset. On error, it is set.
-parseHexPair:
-	push	bc
-
-	ld	a, (hl)
-	call	parseHex
-	jr	c, .end		; error? goto end, keeping the C flag on
-	rla \ rla \ rla \ rla	; let's push this in MSB
-	ld	b, a
-	inc	hl
-	ld	a, (hl)
-	cp	0x21
-	jr	c, .single	; special char? single digit
-	call	parseHex
-	jr	c, .end		; error?
-	or	b		; join left-shifted + new. we're done!
-	; C flag was set on parseHex and is necessarily clear at this point
-	jr	.end
-
-.single:
-	; If we have a single digit, our result is already stored in B, but
-	; we have to right-shift it back.
-	ld	a, b
-	and	0xf0
-	rra \ rra \ rra \ rra
-	dec	hl
-
-.end:
-	pop	bc
-	ret
-
 ; Compares strings pointed to by HL and DE up to A count of characters. If
 ; equal, Z is set. If not equal, Z is reset.
 strncmp:
diff --git a/parts/z80/parse.asm b/parts/z80/parse.asm
new file mode 100644
index 0000000..4a2e313
--- /dev/null
+++ b/parts/z80/parse.asm
@@ -0,0 +1,63 @@
+; Parse the hex char at A and extract it's 0-15 numerical value. Put the result
+; in A.
+;
+; On success, the carry flag is reset. On error, it is set.
+parseHex:
+	; First, let's see if we have an easy 0-9 case
+	cp	'0'
+	jr	c, .error	; if < '0', we have a problem
+	cp	'9'+1
+	jr	nc, .alpha	; if >= '9'+1, we might have alpha
+	; We are in the 0-9 range
+	sub	'0'		; C is clear
+	ret
+
+.alpha:
+	call	upcase
+	cp	'A'
+	jr	c, .error	; if < 'A', we have a problem
+	cp	'F'+1
+	jr	nc, .error	; if >= 'F', we have a problem
+	; We have alpha.
+	sub	'A'-10		; C is clear
+	ret
+
+.error:
+	scf
+	ret
+
+; Parses 2 characters of the string pointed to by HL and returns the numerical
+; value in A. If the second character is a "special" character (<0x21) we don't
+; error out: the result will be the one from the first char only.
+; HL is set to point to the last char of the pair.
+;
+; On success, the carry flag is reset. On error, it is set.
+parseHexPair:
+	push	bc
+
+	ld	a, (hl)
+	call	parseHex
+	jr	c, .end		; error? goto end, keeping the C flag on
+	rla \ rla \ rla \ rla	; let's push this in MSB
+	ld	b, a
+	inc	hl
+	ld	a, (hl)
+	cp	0x21
+	jr	c, .single	; special char? single digit
+	call	parseHex
+	jr	c, .end		; error?
+	or	b		; join left-shifted + new. we're done!
+	; C flag was set on parseHex and is necessarily clear at this point
+	jr	.end
+
+.single:
+	; If we have a single digit, our result is already stored in B, but
+	; we have to right-shift it back.
+	ld	a, b
+	and	0xf0
+	rra \ rra \ rra \ rra
+	dec	hl
+
+.end:
+	pop	bc
+	ret
diff --git a/parts/z80/shell.asm b/parts/z80/shell.asm
index b22f714..194d468 100644
--- a/parts/z80/shell.asm
+++ b/parts/z80/shell.asm
@@ -14,6 +14,7 @@
 ; hexadecimal form, without prefix or suffix.
 
 ; *** REQUIREMENTS ***
+; parse
 ; stdio
 ; blkdev
 
diff --git a/recipes/rc2014/glue.asm b/recipes/rc2014/glue.asm
index c05adbc..a1b8e19 100644
--- a/recipes/rc2014/glue.asm
+++ b/recipes/rc2014/glue.asm
@@ -12,6 +12,7 @@ jp	init
 jp	aciaInt
 
 #include "core.asm"
+#include "parse.asm"
 ACIA_RAMSTART	.equ	RAMSTART
 #include "acia.asm"
 
diff --git a/recipes/rc2014/sdcard/glue.asm b/recipes/rc2014/sdcard/glue.asm
index 3294c44..b9856f1 100644
--- a/recipes/rc2014/sdcard/glue.asm
+++ b/recipes/rc2014/sdcard/glue.asm
@@ -25,6 +25,7 @@ jp	init
 jp	aciaInt
 
 #include "core.asm"
+#include "parse.asm"
 ACIA_RAMSTART	.equ	RAMSTART
 #include "acia.asm"
 BLOCKDEV_RAMSTART	.equ	ACIA_RAMEND
diff --git a/tools/emul/.gitignore b/tools/emul/.gitignore
index b485ee4..d0ec041 100644
--- a/tools/emul/.gitignore
+++ b/tools/emul/.gitignore
@@ -1,7 +1,8 @@
-/shell
-/zasm
-/zasm-includes.h
-/*-kernel.h
-/*-user.h
+/shell/shell
+/zasm/zasm
+/runbin/runbin
+/zasm/includes.*
+/*/kernel.h
+/*/user.h
 /cfsin
 /cfsout
diff --git a/tools/emul/Makefile b/tools/emul/Makefile
index f189a08..514d0d7 100644
--- a/tools/emul/Makefile
+++ b/tools/emul/Makefile
@@ -1,4 +1,4 @@
-TARGETS = shell/shell zasm/zasm
+TARGETS = shell/shell zasm/zasm runbin/runbin
 KERNEL_HEADERS = shell/kernel.h zasm/kernel.h
 USER_HEADERS = zasm/user.h
 CFSPACK = ../cfspack/cfspack
@@ -25,6 +25,7 @@ zasm/includes.h: zasm/includes.cfs
 	
 shell/shell: shell/shell.c libz80/libz80.o shell/kernel.h $(CFSPACK)
 zasm/zasm: zasm/zasm.c libz80/libz80.o zasm/kernel.h zasm/user.h zasm/includes.h
+runbin/runbin: runbin/runbin.c libz80/libz80.o
 $(TARGETS):
 	cc $< libz80/libz80.o -o $@
 
diff --git a/tools/emul/runbin/runbin.c b/tools/emul/runbin/runbin.c
new file mode 100644
index 0000000..a8e6a34
--- /dev/null
+++ b/tools/emul/runbin/runbin.c
@@ -0,0 +1,56 @@
+#include <stdint.h>
+#include <stdio.h>
+#include "../libz80/z80.h"
+
+/* runbin loads binary from stdin directly in memory address 0 then runs it
+ * until it halts. The return code is the value of the register A at halt time.
+ */
+
+static Z80Context cpu;
+static uint8_t mem[0x10000];
+
+static uint8_t io_read(int unused, uint16_t addr)
+{
+    addr &= 0xff;
+    fprintf(stderr, "Out of bounds I/O read: %d\n", addr);
+    return 0;
+}
+
+static void io_write(int unused, uint16_t addr, uint8_t val)
+{
+    addr &= 0xff;
+    fprintf(stderr, "Out of bounds I/O write: %d / %d\n", addr, val);
+}
+
+static uint8_t mem_read(int unused, uint16_t addr)
+{
+    return mem[addr];
+}
+
+static void mem_write(int unused, uint16_t addr, uint8_t val)
+{
+    mem[addr] = val;
+}
+
+int main()
+{
+    // read stdin in mem
+    int i = 0;
+    int c = getchar();
+    while (c != EOF) {
+        mem[i] = c & 0xff;
+        i++;
+        c = getchar();
+    }
+    Z80RESET(&cpu);
+    cpu.ioRead = io_read;
+    cpu.ioWrite = io_write;
+    cpu.memRead = mem_read;
+    cpu.memWrite = mem_write;
+
+    while (!cpu.halted) {
+        Z80Execute(&cpu);
+    }
+    return cpu.R1.br.A;
+}
+
diff --git a/tools/emul/shell/shell_.asm b/tools/emul/shell/shell_.asm
index df25dce..4d8fc58 100644
--- a/tools/emul/shell/shell_.asm
+++ b/tools/emul/shell/shell_.asm
@@ -9,6 +9,7 @@ FS_SEEKH_PORT	.equ	0x03
 jp	init
 
 #include "core.asm"
+#include "parse.asm"
 
 BLOCKDEV_RAMSTART	.equ	RAMSTART
 BLOCKDEV_COUNT		.equ	4
diff --git a/tools/emul/zasm/glue.asm b/tools/emul/zasm/glue.asm
index 851fd9e..405a882 100644
--- a/tools/emul/zasm/glue.asm
+++ b/tools/emul/zasm/glue.asm
@@ -25,6 +25,7 @@ jp	fsSeek
 jp	fsTell
 
 #include "core.asm"
+#include "parse.asm"
 .equ	BLOCKDEV_RAMSTART	RAMSTART
 .equ	BLOCKDEV_COUNT		3
 #include "blockdev.asm"
diff --git a/tools/tests/Makefile b/tools/tests/Makefile
new file mode 100644
index 0000000..563aa51
--- /dev/null
+++ b/tools/tests/Makefile
@@ -0,0 +1,7 @@
+EMULDIR = ../../tools/emul
+
+.PHONY: run
+run:
+	make -C $(EMULDIR) zasm runbin
+	cd unit && ./runtests.sh
+	cd zasm && ./runtests.sh
diff --git a/tools/tests/unit/runtests.sh b/tools/tests/unit/runtests.sh
new file mode 100755
index 0000000..59f954a
--- /dev/null
+++ b/tools/tests/unit/runtests.sh
@@ -0,0 +1,18 @@
+#!/bin/sh
+
+set -e
+set -o pipefail
+
+SCAS=scas
+PARTS=../../../parts/z80
+RUNBIN=../../emul/runbin/runbin
+
+for fn in *.asm; do
+    echo "Running test ${fn}"
+    if ! ${SCAS} -I ${PARTS} -o - ${fn} | ${RUNBIN}; then
+        echo "failed with code ${PIPESTATUS[1]}"
+        exit 1
+    fi
+done
+
+echo "All tests passed!"
diff --git a/tools/tests/unit/test_parse.asm b/tools/tests/unit/test_parse.asm
new file mode 100644
index 0000000..12dac0a
--- /dev/null
+++ b/tools/tests/unit/test_parse.asm
@@ -0,0 +1,67 @@
+jp	test
+
+#include "core.asm"
+#include "parse.asm"
+
+testNum:	.db 1
+
+sFoo:		.db "Foo", 0
+saB:		.db "aB", 0
+s99:		.db "99", 0
+
+test:
+	ld	hl, 0xffff
+	ld	sp, hl
+
+	ld	a, '8'
+	call	parseHex
+	jp	c, fail
+	cp	8
+	jp	nz, fail
+	call	nexttest
+
+	ld	a, 'e'
+	call	parseHex
+	jp	c, fail
+	cp	0xe
+	jp	nz, fail
+	call	nexttest
+
+	ld	a, 'x'
+	call	parseHex
+	jp	nc, fail
+	call	nexttest
+
+	ld	hl, s99
+	call	parseHexPair
+	jp	c, fail
+	cp	0x99
+	jp	nz, fail
+	call	nexttest
+
+	ld	hl, sab
+	call	parseHexPair
+	jp	c, fail
+	cp	0xab
+	jp	nz, fail
+	call	nexttest
+
+	ld	hl, sfoo
+	call	parseHexPair
+	jp	nc, fail
+	call	nexttest
+
+	; success
+	xor	a
+	halt
+
+nexttest:
+	ld	a, (testNum)
+	inc	a
+	ld	(testNum), a
+	ret
+
+fail:
+	ld	a, (testNum)
+	halt
+
diff --git a/tools/tests/zasm/Makefile b/tools/tests/zasm/Makefile
deleted file mode 100644
index b9df97c..0000000
--- a/tools/tests/zasm/Makefile
+++ /dev/null
@@ -1,6 +0,0 @@
-EMULDIR = ../../../tools/emul
-
-.PHONY: run
-run:
-	make -C $(EMULDIR) zasm
-	./runtests.sh