diff --git a/src/emu/cpu/z80/z80.c b/src/emu/cpu/z80/z80.c
index b69c5c6de1b..e943ed48e75 100644
--- a/src/emu/cpu/z80/z80.c
+++ b/src/emu/cpu/z80/z80.c
@@ -3716,16 +3716,16 @@ void z80_device::z80_set_cycle_tables(const UINT8 *op, const UINT8 *cb, const UI
 
 
 z80_device::z80_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
-	cpu_device(mconfig, Z80, "Zilog Z-80", tag, owner, clock, "z80", __FILE__),
+	cpu_device(mconfig, Z80, "Z80", tag, owner, clock, "z80", __FILE__),
 	m_program_config("program", ENDIANNESS_LITTLE, 8, 16, 0),
-	m_io_config("program", ENDIANNESS_LITTLE, 8, 16, 0)
+	m_io_config("io", ENDIANNESS_LITTLE, 8, 16, 0)
 {
 }
 
 z80_device::z80_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock, const char *shortname, const char *source) :
 	cpu_device(mconfig, type, name, tag, owner, clock, shortname, source),
 	m_program_config("program", ENDIANNESS_LITTLE, 8, 16, 0),
-	m_io_config("program", ENDIANNESS_LITTLE, 8, 16, 0)
+	m_io_config("io", ENDIANNESS_LITTLE, 8, 16, 0)
 {
 }
 
diff --git a/src/emu/cpu/z80/z80.h b/src/emu/cpu/z80/z80.h
index fbf4f730827..5b58c3e4ce2 100644
--- a/src/emu/cpu/z80/z80.h
+++ b/src/emu/cpu/z80/z80.h
@@ -51,6 +51,7 @@ protected:
 	virtual UINT32 execute_min_cycles() const { return 2; }
 	virtual UINT32 execute_max_cycles() const { return 16; }
 	virtual UINT32 execute_input_lines() const { return 4; }
+	virtual UINT32 execute_default_irq_vector() const { return 0xff; }
 	virtual void execute_run();
 	virtual void execute_set_input(int inputnum, int state);
 
@@ -63,7 +64,7 @@ protected:
 	virtual void state_string_export(const device_state_entry &entry, astring &string);
 
 	// device_disasm_interface overrides
-	virtual UINT32 disasm_min_opcode_bytes() const { return 4; }
+	virtual UINT32 disasm_min_opcode_bytes() const { return 1; }
 	virtual UINT32 disasm_max_opcode_bytes() const { return 4; }
 	virtual offs_t disasm_disassemble(char *buffer, offs_t pc, const UINT8 *oprom, const UINT8 *opram, UINT32 options);