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The ACIA actually has two clocks, though on an ST they're both 500,000 Hz.

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This commit is contained in:
Thomas Harte 2019-10-13 21:32:34 -04:00
parent f86dc082bb
commit 8d87e9eb1c
3 changed files with 28 additions and 11 deletions
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12
Components/6850/6850.cpp
View File

@ -13,9 +13,13 @@
using namespace Motorola::ACIA;
ACIA::ACIA(int clock_rate) {
transmit.set_writer_clock_rate(clock_rate);
request_to_send.set_writer_clock_rate(clock_rate);
const HalfCycles ACIA::SameAsTransmit;
ACIA::ACIA(HalfCycles transmit_clock_rate, HalfCycles receive_clock_rate) :
transmit_clock_rate_(transmit_clock_rate),
receive_clock_rate_((receive_clock_rate != SameAsTransmit) ? receive_clock_rate : transmit_clock_rate) {
transmit.set_writer_clock_rate(transmit_clock_rate.as_int());
request_to_send.set_writer_clock_rate(transmit_clock_rate.as_int());
}
uint8_t ACIA::read(int address) {
@ -149,6 +153,6 @@ ClockingHint::Preference ACIA::preferred_clocking() {
return (transmit.write_data_time_remaining() > 0) ? ClockingHint::Preference::JustInTime : ClockingHint::Preference::None;
}
bool ACIA::get_interrupt_line() {
bool ACIA::get_interrupt_line() const {
return interrupt_request_;
}

19
Components/6850/6850.hpp
View File

@ -19,7 +19,13 @@ namespace ACIA {
class ACIA: public ClockingHint::Source {
public:
ACIA(int clock_rate);
static constexpr const HalfCycles SameAsTransmit = HalfCycles(0);
/*!
Constructs a new instance of ACIA which will receive a transmission clock at a rate of
@c transmit_clock_rate, and a receive clock at a rate of @c receive_clock_rate.
*/
ACIA(HalfCycles transmit_clock_rate, HalfCycles receive_clock_rate = SameAsTransmit);
/*!
Reads from the ACIA.
@ -39,9 +45,13 @@ class ACIA: public ClockingHint::Source {
*/
void write(int address, uint8_t value);
void run_for(HalfCycles);
/*!
Advances @c transmission_cycles in time, which should be
counted relative to the @c transmit_clock_rate.
*/
void run_for(HalfCycles transmission_cycles);
bool get_interrupt_line();
bool get_interrupt_line() const;
// Input lines.
Serial::Line receive;
@ -69,6 +79,9 @@ class ACIA: public ClockingHint::Source {
bool interrupt_request_ = false;
ClockingHint::Preference preferred_clocking() final;
HalfCycles transmit_clock_rate_;
HalfCycles receive_clock_rate_;
};
}

8
Machines/AtariST/AtariST.cpp
View File

@ -39,8 +39,8 @@ class ConcreteMachine:
public:
ConcreteMachine(const Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
mc68000_(*this),
keyboard_acia_(CLOCK_RATE / 10),
midi_acia_(CLOCK_RATE / 10),
keyboard_acia_(Cycles(500000)),
midi_acia_(Cycles(500000)),
ay_(audio_queue_),
speaker_(ay_) {
set_clock_rate(CLOCK_RATE);
@ -372,8 +372,8 @@ class ConcreteMachine:
HalfCycles cycles_until_video_event_;
JustInTimeActor<Motorola::MFP68901::MFP68901> mfp_;
JustInTimeActor<Motorola::ACIA::ACIA, 10> keyboard_acia_;
JustInTimeActor<Motorola::ACIA::ACIA, 10> midi_acia_;
JustInTimeActor<Motorola::ACIA::ACIA, 16> keyboard_acia_;
JustInTimeActor<Motorola::ACIA::ACIA, 16> midi_acia_;
Concurrency::DeferringAsyncTaskQueue audio_queue_;
GI::AY38910::AY38910 ay_;