MAME SVN History

199869 Revisions

r29408 Monday 7th April, 2014 at 09:09:28 UTC by smf
Support 115200 on Apple III [smf]

[src/emu/machine]	mos6551.c mos6551.h
[src/mess/drivers]	apple3.c

trunk/src/emu/machine/mos6551.c
r29407	r29408
29	29	m_rts(0),
30	30	m_dtr(0),
31	31	m_xtal(0),
	32	m_divide(0),
32	33	m_cts(1),
33	34	m_dsr(1),
34	35	m_dcd(1),
r29407	r29408
39	40
40	41	const int mos6551_device::internal_divider[] =
41	42	{
42		0, 2304, 1536, 1048, 856, 768, 384, 192, 96, 64, 48, 32, 24, 16, 12, 6
	43	1, 2304, 1536, 1048, 856, 768, 384, 192, 96, 64, 48, 32, 24, 16, 12, 6
43	44	};
44	45
45	46	const int mos6551_device::transmitter_controls[4][3] =
r29407	r29408
86	87	save_item(NAME(m_dtr));
87	88
88	89	save_item(NAME(m_xtal));
	90	save_item(NAME(m_divide));
89	91	save_item(NAME(m_cts));
90	92	save_item(NAME(m_dsr));
91	93	save_item(NAME(m_dcd));
r29407	r29408
225	227	}
226	228	}
227	229
	230	void mos6551_device::update_divider()
	231	{
	232	// bits 0-3
	233	double scale = internal_divider[(m_control >> 0) & 0xf];
	234
	235	// The 6551 allows an external clock (hooked up to xtal1 with xtal2 floating) with the internal clock generator,
	236	// it is unknown whether it allows a xtal (hooked up to xtal1 & xtal2) to be used as an external clock. It is
	237	// allowed here for performance reasons.
	238	if (m_xtal != 0)
	239	{
	240	m_tx_internal_clock = true;
	241
	242	m_divide = 16;
	243	scale = (double) 1 / scale;
	244	}
	245	else
	246	{
	247	m_tx_internal_clock = false;
	248
	249	m_divide = scale * 16;
	250	scale = 0;
	251	}
	252
	253	m_internal_clock->set_clock_scale(scale);
	254	}
	255
228	256	UINT8 mos6551_device::read_rdr()
229	257	{
230	258	m_status &= ~(SR_PARITY_ERROR \| SR_FRAMING_ERROR \| SR_OVERRUN \| SR_RDRF);
r29407	r29408
277	305	{
278	306	m_control = data;
279	307
280		// bits 0-3
281		double scale = internal_divider[(m_control >> 0) & 0xf];
282		if (scale != 0)
283		{
284		m_tx_internal_clock = true;
285		scale = (double) 1 / scale;
286		}
287		else
288		{
289		m_tx_internal_clock = false;
290		}
	308	update_divider();
291	309
292		m_internal_clock->set_clock_scale(scale);
293
294	310	// bit 4
295	311	m_rx_internal_clock = (m_control >> 4) & 1;
296	312
r29407	r29408
407	423	if (started())
408	424	{
409	425	m_internal_clock->set_unscaled_clock(m_xtal);
	426	update_divider();
410	427	}
411	428	}
412	429

trunk/src/emu/machine/mos6551.h
r29407	r29408
83	83	virtual machine_config_constructor device_mconfig_additions() const;
84	84
85	85	private:
86		static const int m_divide = 16;
87
88	86	enum
89	87	{
90	88	SR_PARITY_ERROR = 0x01,
r29407	r29408
136	134	void output_dtr(int dtr);
137	135
138	136	void update_irq();
	137	void update_divider();
139	138
140	139	UINT8 read_rdr();
141	140	UINT8 read_status();
r29407	r29408
177	176	int m_dtr;
178	177
179	178	UINT32 m_xtal;
	179	int m_divide;
180	180	int m_cts;
181	181	int m_dsr;
182	182	int m_dcd;

trunk/src/mess/drivers/apple3.c
r29407	r29408
109	109
110	110	/* acia */
111	111	MCFG_DEVICE_ADD("acia", MOS6551, 0)
112		MCFG_MOS6551_XTAL(XTAL_1_8432MHz)
	112	MCFG_MOS6551_XTAL(XTAL_1_8432MHz) // HACK: The schematic shows an external clock generator but using a XTAL is faster to emulate.
113	113	MCFG_MOS6551_IRQ_HANDLER(WRITELINE(apple3_state, apple3_acia_irq_func))
114	114	MCFG_MOS6551_TXD_HANDLER(DEVWRITELINE("rs232", rs232_port_device, write_txd))
115	115	MCFG_MOS6551_RTS_HANDLER(DEVWRITELINE("rs232", rs232_port_device, write_rts))

199869 Revisions