diff --git a/test/test_assemble.c b/test/test_assemble.c
index 837f6cf..40c8bcc 100644
--- a/test/test_assemble.c
+++ b/test/test_assemble.c
@@ -19,7 +19,7 @@ ATF_TC_BODY(assemble_single_buf, tc)
 	uint8_t bsize;
 	uint16_t caddr;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	caddr = ROM_LOAD_ADDR;	
@@ -54,7 +54,7 @@ ATF_TC_BODY(assemble_single, tc)
 	bus_t b;
 	assembler_t a;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	a = assemble_init(&b, ROM_LOAD_ADDR);
 	e = rk65c02_init(&b);
 
diff --git a/test/test_bus.c b/test/test_bus.c
index b548e95..1d76171 100644
--- a/test/test_bus.c
+++ b/test/test_bus.c
@@ -3,6 +3,8 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <utlist.h>
+
 #include "rk65c02.h"
 #include "bus.h"
 #include "utils.h"
@@ -14,7 +16,31 @@ ATF_TC_BODY(bus_init, tc)
 
 	b = bus_init();
 
-	ATF_CHECK(b.space != NULL);
+	ATF_CHECK(b.dm_head == NULL);
+
+	bus_finish(&b);
+}
+
+
+ATF_TC_WITHOUT_HEAD(bus_init_default);
+ATF_TC_BODY(bus_init_default, tc)
+{
+	bus_t b;
+	device_mapping_t *dm;
+	device_t *d, *d_ram;
+
+	b = bus_init_with_default_devs();
+
+	bus_device_dump(&b);
+
+	LL_FOREACH(b.dm_head, dm) {
+		d = dm->dev;
+
+		if (dm->addr == 0) 
+			d_ram = d;
+	}
+
+	ATF_CHECK(strcmp("RAM", d_ram->name) == 0);
 
 	bus_finish(&b);
 }
@@ -25,13 +51,13 @@ ATF_TC_BODY(bus_load_file, tc)
 	bus_t b;
 	const char *rompath;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 
 	rompath = rom_path("test_emulation_nop.rom", tc);
 
 	ATF_REQUIRE(bus_load_file(&b, 0xC000, rompath));
 
-	ATF_CHECK(b.space[0xC000] == 0xEA);
+	ATF_CHECK(bus_read_1(&b, 0xC000) == 0xEA);
 
 	bus_finish(&b);
 }
@@ -43,12 +69,12 @@ ATF_TC_BODY(bus_load_buf, tc)
 
 	uint8_t buf[] = { 0xEA, 0xDB };
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 
 	ATF_REQUIRE(bus_load_buf(&b, 0xC000, buf, 2));
 
-	ATF_CHECK(b.space[0xC000] == 0xEA);
-	ATF_CHECK(b.space[0xC001] == 0xDB);
+	ATF_CHECK(bus_read_1(&b, 0xC000) == 0xEA);
+	ATF_CHECK(bus_read_1(&b, 0xC001) == 0xDB);
 
 	bus_finish(&b);
 }
@@ -56,6 +82,7 @@ ATF_TC_BODY(bus_load_buf, tc)
 ATF_TP_ADD_TCS(tp)
 {
 	ATF_TP_ADD_TC(tp, bus_init);
+	ATF_TP_ADD_TC(tp, bus_init_default);
 	ATF_TP_ADD_TC(tp, bus_load_file);
 	ATF_TP_ADD_TC(tp, bus_load_buf);
 
diff --git a/test/test_debug.c b/test/test_debug.c
index a4fa570..f3231e2 100644
--- a/test/test_debug.c
+++ b/test/test_debug.c
@@ -20,7 +20,7 @@ ATF_TC_BODY(breakpoint, tc)
 	bus_t b;
 	assembler_t a;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	a = assemble_init(&b, ROM_LOAD_ADDR);
 	e = rk65c02_init(&b);
 
@@ -54,7 +54,7 @@ ATF_TC_BODY(trace, tc)
 	trace_t *tr;
 	int i;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	a = assemble_init(&b, ROM_LOAD_ADDR);
 	e = rk65c02_init(&b);
 
diff --git a/test/test_emulation.c b/test/test_emulation.c
index 525d078..2e317f7 100644
--- a/test/test_emulation.c
+++ b/test/test_emulation.c
@@ -16,7 +16,7 @@ ATF_TC_BODY(emul_bit, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* BIT immediate  */
@@ -64,7 +64,7 @@ ATF_TC_BODY(emul_cmp, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* CMP immediate */
@@ -166,7 +166,7 @@ ATF_TC_BODY(emul_cpx, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* CPX immediate */
@@ -203,7 +203,7 @@ ATF_TC_BODY(emul_cpy, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* CPY immediate */
@@ -240,7 +240,7 @@ ATF_TC_BODY(emul_dex_dey, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* DEX  */
@@ -268,7 +268,7 @@ ATF_TC_BODY(emul_dec, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* DEC A */
@@ -324,7 +324,7 @@ ATF_TC_BODY(emul_inc, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* INC A */
@@ -383,7 +383,7 @@ ATF_TC_BODY(emul_inx_iny, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* INX */
@@ -413,7 +413,7 @@ ATF_TC_BODY(emul_lda, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* LDA immediate */
@@ -453,7 +453,7 @@ ATF_TC_BODY(emul_stz, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* STZ zp */
@@ -470,7 +470,7 @@ ATF_TC_BODY(emul_clv, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.P |= P_SIGN_OVERFLOW;
@@ -487,7 +487,7 @@ ATF_TC_BODY(emul_clc_sec, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* SEC */
@@ -507,7 +507,7 @@ ATF_TC_BODY(emul_cli_sei, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* CLI */
@@ -526,7 +526,7 @@ ATF_TC_BODY(emul_and, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* AND immediate */
@@ -548,7 +548,7 @@ ATF_TC_BODY(emul_nop, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.PC = ROM_LOAD_ADDR;
@@ -566,7 +566,7 @@ ATF_TC_BODY(emul_sta, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* STA zero page */
@@ -621,7 +621,7 @@ ATF_TC_BODY(emul_ora, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 	/* ORA immediate */
 	e.regs.A = 0x55;
@@ -688,7 +688,7 @@ ATF_TC_BODY(emul_txa_tya_tax_tay, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.A = 0x0;
@@ -718,7 +718,7 @@ ATF_TC_BODY(emul_stack, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* place 0xAA on stack */
@@ -761,7 +761,7 @@ ATF_TC_BODY(emul_php_plp, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.SP = 0xFF;
@@ -790,7 +790,7 @@ ATF_TC_BODY(emul_phx_phy_plx_ply, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* check push X to stack */
@@ -836,7 +836,7 @@ ATF_TC_BODY(emul_jmp, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* JMP absolute */
@@ -877,7 +877,7 @@ ATF_TC_BODY(emul_jsr_rts, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* JSR and RTS */
@@ -898,7 +898,7 @@ ATF_TC_BODY(emul_branch, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	/* BCC */
@@ -1013,7 +1013,7 @@ ATF_TC_BODY(emul_sign_overflow_basic, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.PC = ROM_LOAD_ADDR;
@@ -1157,7 +1157,7 @@ ATF_TC_BODY(emul_sign_overflow_thorough, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	ATF_REQUIRE(rom_start(&e, "test_emulation_sign_overflow_thorough.rom", tc));
@@ -1171,7 +1171,7 @@ ATF_TC_BODY(emul_sbc, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	ATF_REQUIRE(rom_start(&e, "test_emulation_sbc_imm.rom", tc));
@@ -1187,7 +1187,7 @@ ATF_TC_BODY(emul_adc_bcd, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	ATF_REQUIRE(rom_start(&e, "test_emulation_adc_bcd.rom", tc));
@@ -1211,7 +1211,7 @@ ATF_TC_BODY(emul_sbc_bcd, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	ATF_REQUIRE(rom_start(&e, "test_emulation_sbc_bcd.rom", tc));
@@ -1233,7 +1233,7 @@ ATF_TC_BODY(emul_adc_16bit, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	bus_write_1(&b, 0x62, 0x55);
@@ -1255,7 +1255,7 @@ ATF_TC_BODY(emul_sbc_16bit, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	bus_write_1(&b, 0x62, 0xFF);
@@ -1285,7 +1285,7 @@ ATF_TC_BODY(emul_rmb, tc)
 
 	char instr[] = "rmb ";
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	a = assemble_init(&b, ROM_LOAD_ADDR);
 	e = rk65c02_init(&b);
 
@@ -1324,7 +1324,7 @@ ATF_TC_BODY(emul_smb, tc)
 
 	char instr[] = "smb ";
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	a = assemble_init(&b, ROM_LOAD_ADDR);
 	e = rk65c02_init(&b);
 
diff --git a/test/test_interrupt.c b/test/test_interrupt.c
index 404d272..5ea77e9 100644
--- a/test/test_interrupt.c
+++ b/test/test_interrupt.c
@@ -23,7 +23,7 @@ ATF_TC_BODY(intr_brk, tc)
 	rk65c02emu_t e;	
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.PC = ROM_LOAD_ADDR;
@@ -74,7 +74,7 @@ ATF_TC_BODY(intr_rti, tc)
 	uint16_t israsmpc;
 	uint8_t bsize;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	israsmpc = ISR_ADDR;
diff --git a/test/test_stepping.c b/test/test_stepping.c
index 7d12c49..60ffb4c 100644
--- a/test/test_stepping.c
+++ b/test/test_stepping.c
@@ -12,7 +12,7 @@ ATF_TC_BODY(step1, tc)
 	rk65c02emu_t e;
 	bus_t b;
 
-	b = bus_init();
+	b = bus_init_with_default_devs();
 	e = rk65c02_init(&b);
 
 	e.regs.PC = ROM_LOAD_ADDR;