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Nudges 6850 towards coherence.

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This commit is contained in:
Thomas Harte 2019-10-12 00:04:02 -04:00
parent 97d44129cb
commit 4b09d7c41d
2 changed files with 38 additions and 1 deletions
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20
Components/6850/6850.cpp
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@ -8,13 +8,31 @@
#include "6850.hpp" #include "6850.hpp"
#define LOG_PREFIX "[6850] "
#include "../../Outputs/Log.hpp"
using namespace Motorola::ACIA; using namespace Motorola::ACIA;
uint8_t ACIA::read(int address) { uint8_t ACIA::read(int address) {
return 0xff; if(address&1) {
LOG("Read from receive register");
} else {
LOG("Read status");
return status_;
}
return 0x00;
} }
void ACIA::write(int address, uint8_t value) { void ACIA::write(int address, uint8_t value) {
if(address&1) {
LOG("Write to transmit register");
} else {
if((value&3) == 3) {
LOG("Reset");
} else {
LOG("Write to control register");
}
}
} }
void ACIA::run_for(HalfCycles) { void ACIA::run_for(HalfCycles) {

19
Components/6850/6850.hpp
View File

@ -17,10 +17,29 @@ namespace ACIA {
class ACIA { class ACIA {
public: public:
/*!
Reads from the ACIA.
Bit 0 of the address is used as the ACIA's register select line —
so even addresses select control/status registers, odd addresses
select transmit/receive data registers.
*/
uint8_t read(int address); uint8_t read(int address);
/*!
Writes to the ACIA.
Bit 0 of the address is used as the ACIA's register select line —
so even addresses select control/status registers, odd addresses
select transmit/receive data registers.
*/
void write(int address, uint8_t value); void write(int address, uint8_t value);
void run_for(HalfCycles); void run_for(HalfCycles);
private:
int divider_ = 1;
uint8_t status_ = 0x00;
}; };
} }