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improved cpu clock and speaker lvl

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This commit is contained in:
hap 2014-11-04 21:07:31 +01:00
parent 282a6e03a5
commit 71933553c1
1 changed files with 20 additions and 12 deletions
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32
src/mess/drivers/merlin.c
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@ -13,6 +13,7 @@
TODO:
- accurate rc osc
- accurate speaker levels (tone pitch sounds good though)
- is the rom dump good?
***************************************************************************/
@ -23,8 +24,9 @@
#include "merlin.lh"
// master clock is a single stage RC oscillator: R=?, C=?
#define MERLIN_RC_CLOCK (500000)
// master clock is a single stage RC oscillator: R=27K, C=100pf
// this is an approximation compared with recordings
#define MERLIN_RC_CLOCK (355000)
class merlin_state : public driver_device
@ -37,17 +39,18 @@ public:
m_speaker(*this, "speaker")
{ }
required_device<cpu_device> m_maincpu;
required_ioport_array<4> m_button_matrix;
required_device<speaker_sound_device> m_speaker;
UINT16 m_o;
DECLARE_READ8_MEMBER(read_k);
DECLARE_WRITE16_MEMBER(write_o);
DECLARE_WRITE16_MEMBER(write_r);
virtual void machine_start();
protected:
required_device<cpu_device> m_maincpu;
required_ioport_array<4> m_button_matrix;
required_device<speaker_sound_device> m_speaker;
UINT16 m_o;
};
@ -94,15 +97,17 @@ READ8_MEMBER(merlin_state::read_k)
WRITE16_MEMBER(merlin_state::write_o)
{
// O0-O3: input mux
m_o = data;
/* The speaker is connected to O4 through O6. The 3 outputs are paralleled for
increased current driving capability. They are passed thru a 220 ohm resistor
and then to the speaker, which has the other side grounded. The software then
toggles these lines to make sounds and noises. (There is no audio generator
other than toggling it with a software delay between to make tones). */
m_speaker->level_w(m_o & 0x70);
static const int count[8] = { 0, 1, 1, 2, 1, 2, 2, 3 };
m_speaker->level_w(count[data >> 4 & 7]);
// O0-O3: input mux
// O7: N/C
m_o = data;
}
WRITE16_MEMBER(merlin_state::write_r)
@ -177,6 +182,8 @@ static const UINT16 merlin_output_pla[0x20] =
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
static const INT16 speaker_levels[] = { 0, 32767, 0, 32767 }; // unknown too, due to output_pla being unknown
static MACHINE_CONFIG_START( merlin, merlin_state )
@ -194,6 +201,7 @@ static MACHINE_CONFIG_START( merlin, merlin_state )
/* sound hardware */
MCFG_SPEAKER_STANDARD_MONO("mono")
MCFG_SOUND_ADD("speaker", SPEAKER_SOUND, 0)
MCFG_SPEAKER_LEVELS(4, speaker_levels)
MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.25)
MACHINE_CONFIG_END