summaryrefslogtreecommitdiffstatshomepage
path: root/src
diff options
context:
space:
mode:
author R. Belmont <rb6502@users.noreply.github.com>2015-08-17 09:37:30 -0400
committer R. Belmont <rb6502@users.noreply.github.com>2015-08-17 09:37:30 -0400
commit6a870588f2141f70449ad2bc6e23024e8b108fd8 (patch)
treef66b6d1659a676357348093340468ce58bfe08c3 /src
parent45854fab0108829ee7b1964532207af2f5b2dac8 (diff)
parent039973b6d8e326b844693ffe0abb3053e6768e1d (diff)
Merge pull request #280 from richard42/trs80-coco-audio-fixes
Trs80 coco audio fixes
Diffstat (limited to 'src')
-rw-r--r--src/mess/includes/coco.h9
-rw-r--r--src/mess/includes/coco12.h2
-rw-r--r--src/mess/includes/dragon.h4
-rw-r--r--src/mess/machine/coco.c50
-rw-r--r--src/mess/machine/coco12.c5
-rw-r--r--src/mess/machine/dragon.c12
6 files changed, 50 insertions, 32 deletions
diff --git a/src/mess/includes/coco.h b/src/mess/includes/coco.h
index a43af0d40f0..363fcff5d2a 100644
--- a/src/mess/includes/coco.h
+++ b/src/mess/includes/coco.h
@@ -153,8 +153,8 @@ protected:
void recalculate_firq(void);
// changed handlers
- virtual void pia1_pa_changed(void);
- virtual void pia1_pb_changed(void);
+ virtual void pia1_pa_changed(UINT8 data);
+ virtual void pia1_pb_changed(UINT8 data);
// miscellaneous
virtual void update_keyboard_input(UINT8 value, UINT8 z);
@@ -208,7 +208,6 @@ private:
bool is_joystick_hires(int joystick_index);
soundmux_status_t soundmux_status(void);
- UINT8 sound_value(void);
void update_sound(void);
bool joyin(void);
void poll_joystick(bool *joyin, UINT8 *buttons);
@@ -244,6 +243,10 @@ private:
// DAC output
UINT8 m_dac_output;
+ // remember the last audio sample level from the analog sources (DAC, cart, cassette) so that we don't
+ // introduce step changes when the audio output is enabled/disabled via PIA1 CB2
+ UINT8 m_analog_audio_level;
+
// hires interface
emu_timer *m_hiresjoy_transition_timer[2];
bool m_hiresjoy_ca;
diff --git a/src/mess/includes/coco12.h b/src/mess/includes/coco12.h
index c264ad092e5..030adc35b25 100644
--- a/src/mess/includes/coco12.h
+++ b/src/mess/includes/coco12.h
@@ -56,7 +56,7 @@ protected:
virtual void update_cart_base(UINT8 *cart_base);
/* PIA1 */
- virtual void pia1_pb_changed(void);
+ virtual void pia1_pb_changed(UINT8 data);
private:
diff --git a/src/mess/includes/dragon.h b/src/mess/includes/dragon.h
index 6db0d5f86a2..7006d37e68d 100644
--- a/src/mess/includes/dragon.h
+++ b/src/mess/includes/dragon.h
@@ -45,7 +45,7 @@ public:
required_device<printer_image_device> m_printer;
protected:
- virtual void pia1_pa_changed(void);
+ virtual void pia1_pa_changed(UINT8 data);
};
@@ -65,7 +65,7 @@ protected:
virtual DECLARE_READ8_MEMBER( ff00_read );
virtual DECLARE_WRITE8_MEMBER( ff00_write );
- virtual void pia1_pb_changed(void);
+ virtual void pia1_pb_changed(UINT8 data);
void page_rom(bool romswitch);
};
diff --git a/src/mess/machine/coco.c b/src/mess/machine/coco.c
index 7994f5b9caa..d28fa1b3412 100644
--- a/src/mess/machine/coco.c
+++ b/src/mess/machine/coco.c
@@ -183,6 +183,7 @@ void coco_state::device_reset()
/* reset state */
m_dac_output = 0;
+ m_analog_audio_level = 0;
m_hiresjoy_ca = false;
m_dclg_previous_bit = false;
m_dclg_output_h = 0;
@@ -364,7 +365,7 @@ WRITE8_MEMBER( coco_state::pia0_pb_w )
WRITE_LINE_MEMBER( coco_state::pia0_ca2_w )
{
- update_sound();
+ update_sound(); // analog mux SEL1 is tied to PIA0 CA2
poll_keyboard();
}
@@ -376,7 +377,7 @@ WRITE_LINE_MEMBER( coco_state::pia0_ca2_w )
WRITE_LINE_MEMBER( coco_state::pia0_cb2_w )
{
- update_sound();
+ update_sound(); // analog mux SEL2 is tied to PIA0 CB2
poll_keyboard();
}
@@ -456,6 +457,8 @@ WRITE8_MEMBER( coco_state::ff20_write )
READ8_MEMBER( coco_state::pia1_pa_r )
{
+ // Port A: we need to specify the values of all the lines, regardless of whether
+ // they are in input or output mode in the DDR
return (m_cassette->input() >= 0 ? 0x01 : 0x00)
| (dac_output() << 2);
}
@@ -470,6 +473,8 @@ READ8_MEMBER( coco_state::pia1_pa_r )
READ8_MEMBER( coco_state::pia1_pb_r )
{
+ // Port B: lines in output mode are handled automatically by the PIA object.
+ // We only need to specify the input lines here
UINT32 ram_size = m_ram->size();
// For the CoCo 1, the logic has been changed to only select 64K rams
@@ -479,7 +484,7 @@ READ8_MEMBER( coco_state::pia1_pb_r )
// to access 32K of ram, and also allows the cocoe driver to access
// the full 64K, as this uses Color Basic 1.2, which can configure 64K rams
bool memory_sense = (ram_size >= 0x4000 && ram_size <= 0x7FFF)
- || (ram_size >= 0x8000 && (m_pia_0->b_output() & 0x80));
+ || (ram_size >= 0x8000 && (m_pia_0->b_output() & 0x40));
// serial in (PB0)
bool serial_in = (m_rs232 != NULL) && (m_rs232->rxd_r() ? true : false);
@@ -497,7 +502,7 @@ READ8_MEMBER( coco_state::pia1_pb_r )
WRITE8_MEMBER( coco_state::pia1_pa_w )
{
- pia1_pa_changed();
+ pia1_pa_changed(data);
}
@@ -508,7 +513,7 @@ WRITE8_MEMBER( coco_state::pia1_pa_w )
WRITE8_MEMBER( coco_state::pia1_pb_w )
{
- pia1_pb_changed();
+ pia1_pb_changed(data);
}
@@ -532,11 +537,7 @@ WRITE_LINE_MEMBER( coco_state::pia1_ca2_w )
WRITE_LINE_MEMBER( coco_state::pia1_cb2_w )
{
- poll_keyboard();
-
- // Theoretically, I should be calling update_sound() here; however this seems to create
- // a buzzing in some CoCo software (e.g. - Popcorn). This is likely because this line
- // drives the MC14529B MUX, and when disabled the output probably goes hi-Z.
+ update_sound(); // SOUND_ENABLE is connected to PIA1 CB2
}
@@ -689,10 +690,25 @@ void coco_state::update_sound(void)
UINT8 cassette_sound = (bCassSoundEnable ? 0x40 : 0);
UINT8 cart_sound = (bCartSoundEnable ? 0x40 : 0);
- /* determine the value to send to the DAC */
+ /* determine the value to send to the DAC (this is used by the Joystick read as well as audio out) */
m_dac_output = (m_pia_1->a_output() & 0xFC) >> 2;
UINT8 dac_sound = (status == SOUNDMUX_ENABLE ? m_dac_output << 1 : 0);
- m_dac->write_unsigned8(single_bit_sound + dac_sound + cassette_sound + cart_sound);
+
+ /* The CoCo uses a single DAC for both audio output and joystick axis position measurement.
+ * To avoid introducing artifacts while reading the axis positions, some software will disable
+ * the audio output while using the DAC to read the joystick. On a real CoCo, there is a low-pass
+ * filter (C57 on the CoCo 3) which will hold the audio level for very short periods of time,
+ * preventing the introduction of artifacts while the joystick value is being read. We are not going
+ * to simulate the exponential decay of a capacitor here. Instead, we will store and hold the last
+ * used analog audio output value while the audio is disabled, to avoid introducing artifacts in
+ * software such as Tandy's Popcorn and Sock Master's Donkey Kong.
+ */
+ if ((status & SOUNDMUX_ENABLE) != 0)
+ {
+ m_analog_audio_level = dac_sound + cassette_sound + cart_sound;
+ }
+
+ m_dac->write_unsigned8(single_bit_sound + m_analog_audio_level);
/* determine the cassette sound status */
cassette_state cas_sound = bCassSoundEnable ? CASSETTE_SPEAKER_ENABLED : CASSETTE_SPEAKER_MUTED;
@@ -981,12 +997,12 @@ void coco_state::update_prinout(bool prinout)
// pia1_pa_changed - called when PIA1 PA changes
//-------------------------------------------------
-void coco_state::pia1_pa_changed(void)
+void coco_state::pia1_pa_changed(UINT8 data)
{
- update_sound();
+ update_sound(); // DAC is connected to PIA1 PA2-PA7
poll_keyboard();
update_cassout(dac_output());
- update_prinout(m_pia_1->a_output() & 0x02 ? true : false);
+ update_prinout(data & 0x02 ? true : false);
}
@@ -995,9 +1011,9 @@ void coco_state::pia1_pa_changed(void)
// pia1_pb_changed - called when PIA1 PB changes
//-------------------------------------------------
-void coco_state::pia1_pb_changed(void)
+void coco_state::pia1_pb_changed(UINT8 data)
{
- update_sound();
+ update_sound(); // singe_bit_sound is connected to PIA1 PB1
}
diff --git a/src/mess/machine/coco12.c b/src/mess/machine/coco12.c
index c9a0a9a2afb..e2f3fbdb521 100644
--- a/src/mess/machine/coco12.c
+++ b/src/mess/machine/coco12.c
@@ -94,12 +94,11 @@ READ8_MEMBER( coco12_state::sam_read )
// pia1_pb_changed
//-------------------------------------------------
-void coco12_state::pia1_pb_changed(void)
+void coco12_state::pia1_pb_changed(UINT8 data)
{
/* call inherited function */
- coco_state::pia1_pb_changed();
+ coco_state::pia1_pb_changed(data);
- UINT8 data = m_pia_1->b_output();
m_vdg->css_w(data & 0x08);
m_vdg->intext_w(data & 0x10);
m_vdg->gm0_w(data & 0x10);
diff --git a/src/mess/machine/dragon.c b/src/mess/machine/dragon.c
index ded7ff221e5..12c902d5c93 100644
--- a/src/mess/machine/dragon.c
+++ b/src/mess/machine/dragon.c
@@ -48,13 +48,13 @@ easier to manage.
// pia1_pa_changed - called when PIA1 PA changes
//-------------------------------------------------
-void dragon_state::pia1_pa_changed(void)
+void dragon_state::pia1_pa_changed(UINT8 data)
{
/* call inherited function */
- coco12_state::pia1_pa_changed();
+ coco12_state::pia1_pa_changed(data);
/* if strobe bit is high send data from pia0 port b to dragon parallel printer */
- if (m_pia_1->a_output() & 0x02)
+ if (data & 0x02)
{
UINT8 output = m_pia_1->b_output();
m_printer->output(output);
@@ -113,9 +113,9 @@ WRITE8_MEMBER( dragon64_state::ff00_write )
// pia1_pb_changed
//-------------------------------------------------
-void dragon64_state::pia1_pb_changed(void)
+void dragon64_state::pia1_pb_changed(UINT8 data)
{
- dragon_state::pia1_pb_changed();
+ dragon_state::pia1_pb_changed(data);
UINT8 ddr = ~m_pia_1->port_b_z_mask();
@@ -125,7 +125,7 @@ void dragon64_state::pia1_pb_changed(void)
/* always be high (enabling 32k basic rom) */
if (ddr & 0x04)
{
- page_rom(m_pia_1->b_output() & 0x04 ? true : false);
+ page_rom(data & 0x04 ? true : false);
logerror("pia1_pb_changed\n");
}
}