diff --git a/src/emu/machine/ram.h b/src/emu/machine/ram.h
index a144fa6cd47..fefb440d5b5 100644
--- a/src/emu/machine/ram.h
+++ b/src/emu/machine/ram.h
@@ -58,6 +58,10 @@ public:
 	static UINT32 parse_string(const char *s);
 	UINT32 default_size(void) const;
 	const char *extra_options(void) const { return m_extra_options; }
+	
+	// read/write
+	UINT8 read(offs_t offset)				{ return m_pointer[offset % m_size]; }
+	void write(offs_t offset, UINT8 data)	{ m_pointer[offset % m_size] = data; }
 
 	// inline configuration helpers
 	static void static_set_default_size(device_t &device, const char *default_size)		{ downcast<ram_device &>(device).m_default_size = default_size; }
diff --git a/src/mess/machine/coco12.c b/src/mess/machine/coco12.c
index c7239288d5e..f7235484566 100644
--- a/src/mess/machine/coco12.c
+++ b/src/mess/machine/coco12.c
@@ -80,7 +80,7 @@ WRITE_LINE_MEMBER( coco12_state::field_sync )
 
 READ8_MEMBER( coco12_state::sam_read )
 {
-	UINT8 data = m_sam->mpu_address_space()->read_byte(offset);
+	UINT8 data = m_ram->read(offset);
 	m_vdg->as_w(data & 0x80 ? ASSERT_LINE : CLEAR_LINE);
 	m_vdg->inv_w(data & 0x40 ? ASSERT_LINE : CLEAR_LINE);
 	return data;