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Fixed state machine and made TC signal asynchronous.

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This commit is contained in:
Michael Zapf 2020-04-06 13:50:53 +02:00
parent c5b838bc2c
commit 48feef4ac8
2 changed files with 34 additions and 17 deletions
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43
src/devices/machine/74161.cpp
View File

@ -28,8 +28,9 @@ ttl7416x_device::ttl7416x_device(const machine_config &mconfig, device_type type
, m_cep(0) , m_cep(0)
, m_pclock(0) , m_pclock(0)
, m_p(0) , m_p(0)
, m_cetpre(0)
, m_ceppre(0)
, m_out(0) , m_out(0)
, m_tc(0)
, m_synchronous_reset(synchronous_reset) , m_synchronous_reset(synchronous_reset)
, m_limit(limit) , m_limit(limit)
{ {
@ -64,7 +65,6 @@ void ttl7416x_device::device_start()
save_item(NAME(m_pclock)); save_item(NAME(m_pclock));
save_item(NAME(m_p)); save_item(NAME(m_p));
save_item(NAME(m_out)); save_item(NAME(m_out));
save_item(NAME(m_tc));
m_output_func.resolve_safe(); m_output_func.resolve_safe();
m_tc_func.resolve_safe(); m_tc_func.resolve_safe();
@ -79,15 +79,12 @@ void ttl7416x_device::init()
{ {
m_clear = 0; m_clear = 0;
m_pe = 1; m_pe = 1;
m_cet = 0; m_cet = m_cetpre;
m_cep = 0; m_cep = m_ceppre;
m_pclock = 0; m_pclock = 0;
m_p = 0; m_p = 0;
m_out = 0; m_out = 0;
m_tc = 0;
m_tc = 0;
} }
void ttl7416x_device::tick() void ttl7416x_device::tick()
@ -99,7 +96,7 @@ void ttl7416x_device::tick()
} }
uint8_t last_out = m_out; uint8_t last_out = m_out;
uint8_t last_tc = m_tc; uint8_t last_tc = tc_r();
if (m_pe) if (m_pe)
{ {
@ -118,20 +115,30 @@ void ttl7416x_device::tick()
m_output_func(m_out); m_output_func(m_out);
} }
if (m_tc != last_tc) if (tc_r() != last_tc)
{ {
m_tc_func(m_tc); m_tc_func(tc_r());
} }
} }
/*
State machine:
limit 16: 0->1->2->...->e->f(tc)->0
limit 10: 0->1->2->...->9(tc)->0
10->11->4(no tc)
12->13->4(no tc)
14->15->0(no tc)
*/
void ttl7416x_device::increment() void ttl7416x_device::increment()
{ {
m_out = (m_out + 1) % (m_limit + 1); m_out++;
if (m_out == m_limit) if (m_limit == 10)
m_tc = 1; {
else if (m_out == 12 || m_out == 14) m_out = 4;
m_tc = 0; if (m_out == 10) m_out = 0;
}
m_out &= 0x0f;
} }
WRITE_LINE_MEMBER( ttl7416x_device::clear_w ) WRITE_LINE_MEMBER( ttl7416x_device::clear_w )
@ -201,7 +208,11 @@ READ_LINE_MEMBER( ttl7416x_device::output_r )
return m_out; return m_out;
} }
/*
TC is an asynchronous signal, depending on the current states of CET, CEP,
and the counter value.
*/
READ_LINE_MEMBER( ttl7416x_device::tc_r ) READ_LINE_MEMBER( ttl7416x_device::tc_r )
{ {
return m_tc; return ((m_cet==1) && (m_cep==1) && (m_out==m_limit-1))? 1:0;
} }

8
src/devices/machine/74161.h
View File

@ -82,6 +82,9 @@ public:
DECLARE_READ_LINE_MEMBER( output_r ); DECLARE_READ_LINE_MEMBER( output_r );
DECLARE_READ_LINE_MEMBER( tc_r ); DECLARE_READ_LINE_MEMBER( tc_r );
void set_cet_pin_value(int value) { m_cetpre = value; }
void set_cep_pin_value(int value) { m_ceppre = value; }
protected: protected:
// construction/destruction // construction/destruction
ttl7416x_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock, bool synchronous_reset, uint8_t limit); ttl7416x_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock, bool synchronous_reset, uint8_t limit);
@ -111,9 +114,12 @@ private:
uint8_t m_pclock; // pin 2 uint8_t m_pclock; // pin 2
uint8_t m_p; // pins 3-6 from LSB to MSB uint8_t m_p; // pins 3-6 from LSB to MSB
// Preset inputs
uint8_t m_cetpre;
uint8_t m_ceppre;
// outputs // outputs
uint8_t m_out; // pins 14-11 from LSB to MSB uint8_t m_out; // pins 14-11 from LSB to MSB
uint8_t m_tc; // pin 15
const bool m_synchronous_reset; const bool m_synchronous_reset;
const uint8_t m_limit; const uint8_t m_limit;