diff --git a/src/emu/cpu/m6502/m4510.c b/src/emu/cpu/m6502/m4510.c
index 733b53ae91c..3c5ae08ff94 100644
--- a/src/emu/cpu/m6502/m4510.c
+++ b/src/emu/cpu/m6502/m4510.c
@@ -153,8 +153,9 @@ struct _m4510_Regs {
 
 	UINT8    ddr;
 	UINT8    port;
-	m6510_port_read_func port_read;
-	m6510_port_write_func port_write;
+	
+	devcb_resolved_read8	in_port_func;
+	devcb_resolved_write8	out_port_func;
 };
 
 INLINE m4510_Regs *get_safe_token(device_t *device)
@@ -202,8 +203,6 @@ static CPU_INIT( m4510 )
 	cpustate->interrupt_inhibit = 0;
 	cpustate->rdmem_id = default_rdmem_id;
 	cpustate->wrmem_id = default_wrmem_id;
-	cpustate->port_read = NULL;
-	cpustate->port_write = NULL;
 	cpustate->irq_callback = irqcallback;
 	cpustate->device = device;
 	cpustate->space = device->space(AS_PROGRAM);
@@ -217,11 +216,8 @@ static CPU_INIT( m4510 )
 		if ( intf->write_indexed_func )
 			cpustate->wrmem_id = intf->write_indexed_func;
 
-		if ( intf->port_read_func )
-			cpustate->port_read = intf->port_read_func;
-
-		if ( intf->port_write_func )
-			cpustate->port_write = intf->port_write_func;
+		devcb_resolve_read8(&cpustate->in_port_func, &intf->in_port_func, device);
+		devcb_resolve_write8(&cpustate->out_port_func, &intf->out_port_func, device);
 	}
 }
 
@@ -366,8 +362,7 @@ static READ8_HANDLER( m4510_read_0000 )
 			result = cpustate->ddr;
 			break;
 		case 0x0001:	/* Data Port */
-			if (cpustate->port_read)
-				result = cpustate->port_read(cpustate->device, 0);
+			result = devcb_call_read8(&cpustate->in_port_func, 0);
 			result = (cpustate->ddr & cpustate->port) | (~cpustate->ddr & result);
 			break;
 	}
@@ -388,8 +383,7 @@ static WRITE8_HANDLER( m4510_write_0000 )
 			break;
 	}
 
-	if (cpustate->port_write)
-		cpustate->port_write(cpustate->device, 0, m4510_get_port(downcast<legacy_cpu_device *>(&space->device())));
+	devcb_call_write8(&cpustate->out_port_func, 0, m4510_get_port(downcast<legacy_cpu_device *>(&space->device())));
 }
 
 static ADDRESS_MAP_START(m4510_mem, AS_PROGRAM, 8)
diff --git a/src/emu/cpu/m6502/m6502.c b/src/emu/cpu/m6502/m6502.c
index e3928dfad68..a34833243cb 100644
--- a/src/emu/cpu/m6502/m6502.c
+++ b/src/emu/cpu/m6502/m6502.c
@@ -81,8 +81,9 @@ struct _m6502_Regs
 
 	UINT8    ddr;
 	UINT8    port;
-	m6510_port_read_func port_read;
-	m6510_port_write_func port_write;
+	
+	devcb_resolved_read8	in_port_func;
+	devcb_resolved_write8	out_port_func;
 };
 
 INLINE m6502_Regs *get_safe_token(device_t *device)
@@ -142,8 +143,6 @@ static void m6502_common_init(legacy_cpu_device *device, device_irq_callback irq
 	cpustate->insn = insn;
 	cpustate->rdmem_id = default_rdmem_id;
 	cpustate->wrmem_id = default_wdmem_id;
-	cpustate->port_read = NULL;
-	cpustate->port_write = NULL;
 
 	if ( intf )
 	{
@@ -153,11 +152,8 @@ static void m6502_common_init(legacy_cpu_device *device, device_irq_callback irq
 		if ( intf->write_indexed_func )
 			cpustate->wrmem_id = intf->write_indexed_func;
 
-		if ( intf->port_read_func )
-			cpustate->port_read = intf->port_read_func;
-
-		if ( intf->port_write_func )
-			cpustate->port_write = intf->port_write_func;
+		devcb_resolve_read8(&cpustate->in_port_func, &intf->in_port_func, device);
+		devcb_resolve_write8(&cpustate->out_port_func, &intf->out_port_func, device);
 	}
 
 	device->save_item(NAME(cpustate->pc.w.l));
@@ -374,8 +370,7 @@ static READ8_HANDLER( m6510_read_0000 )
 			result = cpustate->ddr;
 			break;
 		case 0x0001:	/* Data Port */
-			if (cpustate->port_read)
-				result = cpustate->port_read( cpustate->device, cpustate->ddr );
+			result = devcb_call_read8(&cpustate->in_port_func, cpustate->ddr);
 			result = (cpustate->ddr & cpustate->port) | (~cpustate->ddr & result);
 			break;
 	}
@@ -396,8 +391,7 @@ static WRITE8_HANDLER( m6510_write_0000 )
 			break;
 	}
 
-	if (cpustate->port_write)
-		cpustate->port_write( cpustate->device, cpustate->ddr, cpustate->port & cpustate->ddr );
+	devcb_call_write8(&cpustate->out_port_func, cpustate->ddr, cpustate->port & cpustate->ddr);
 }
 
 static ADDRESS_MAP_START(m6510_mem, AS_PROGRAM, 8)
diff --git a/src/emu/cpu/m6502/m6502.h b/src/emu/cpu/m6502/m6502.h
index b478fefdb0c..c9ebf634dc7 100644
--- a/src/emu/cpu/m6502/m6502.h
+++ b/src/emu/cpu/m6502/m6502.h
@@ -51,9 +51,6 @@ enum
    positiv edge sets overflow flag */
 #define M6502_SET_OVERFLOW	1
 
-typedef UINT8 (*m6510_port_read_func)(device_t *device, UINT8 direction);
-typedef void (*m6510_port_write_func)(device_t *device, UINT8 direction, UINT8 data);
-
 
 /* Optional interface to set callbacks */
 typedef struct _m6502_interface m6502_interface;
@@ -61,8 +58,8 @@ struct _m6502_interface
 {
 	read8_space_func		read_indexed_func;
 	write8_space_func		write_indexed_func;
-	m6510_port_read_func	port_read_func;
-	m6510_port_write_func	port_write_func;
+	devcb_read8				in_port_func;
+	devcb_write8			out_port_func;
 };
 
 DECLARE_LEGACY_CPU_DEVICE(M6502, m6502);