Previous

199869 Revisions

Next

r23539 Saturday 8th June, 2013 at 12:32:49 UTC by Michael Zapf
ti99: Changed behaviour of memory cells (invert even addresses), may help with some programs that assume power-on default values. (nw)

[src/mess/machine/ti99]

ti32kmem.c

trunk/src/mess/machine/ti99/ti32kmem.c

r23538	r23539
36	36
37	37	READ8Z_MEMBER(ti_32k_expcard_device::readz)
38	38	{
	39	UINT8 val = 0;
	40	bool access = true;
39	41	switch((offset & 0xe000)>>13)
40	42	{
41	43	case 1:
42		*value = m_ram_ptr[offset & 0x1fff];
	44	val = m_ram_ptr[offset & 0x1fff];
43	45	break;
44	46	case 5:
45		*value = m_ram_ptr[(offset & 0x1fff) | 0x2000];
	47	val = m_ram_ptr[(offset & 0x1fff) | 0x2000];
46	48	break;
47	49	case 6:
48		*value = m_ram_ptr[(offset & 0x1fff) | 0x4000];
	50	val = m_ram_ptr[(offset & 0x1fff) | 0x4000];
49	51	break;
50	52	case 7:
51		*value = m_ram_ptr[(offset & 0x1fff) | 0x6000];
	53	val = m_ram_ptr[(offset & 0x1fff) | 0x6000];
52	54	break;
53	55	default:
	56	access = false;
54	57	break;
55	58	}
	59	if (access)
	60	{
	61	if ((offset&1)!=1) *value = ~val;
	62	else *value = val;
	63	}
56	64	}
57	65
58	66	WRITE8_MEMBER(ti_32k_expcard_device::write)
59	67	{
	68	UINT8 data1 = data;
	69	if ((offset&1)!=1) data1 = ~data;
60	70	switch((offset & 0xe000)>>13)
61	71	{
62	72	case 1:
63		m_ram_ptr[offset & 0x1fff] = data;
	73	m_ram_ptr[offset & 0x1fff] = data1;
64	74	break;
65	75	case 5:
66		m_ram_ptr[(offset & 0x1fff) | 0x2000] = data;
	76	m_ram_ptr[(offset & 0x1fff) | 0x2000] = data1;
67	77	break;
68	78	case 6:
69		m_ram_ptr[(offset & 0x1fff) | 0x4000] = data;
	79	m_ram_ptr[(offset & 0x1fff) | 0x4000] = data1;
70	80	break;
71	81	case 7:
72		m_ram_ptr[(offset & 0x1fff) | 0x6000] = data;
	82	m_ram_ptr[(offset & 0x1fff) | 0x6000] = data1;
73	83	break;
74	84	default:
75	85	break;

Previous

199869 Revisions

Next

---

© 1997-2024 The MAME Team