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Produce incorrect output from proper clock; capture mode.

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This commit is contained in:
Thomas Harte 2023-12-05 23:01:08 -05:00
parent fdd599e71a
commit e43f960934
3 changed files with 40 additions and 23 deletions
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61
Machines/PCCompatible/CGA.hpp
View File

@ -19,8 +19,8 @@ class CGA {
public:
CGA() : crtc_(Motorola::CRTC::Personality::HD6845S, outputter_) {}
static constexpr uint32_t BaseAddress = 0xb'0000;
static constexpr auto FontROM = ROM::Name::PCCompatibleMDAFont;
static constexpr uint32_t BaseAddress = 0xb'8000;
static constexpr auto FontROM = ROM::Name::PCCompatibleCGAFont;
void set_source(const uint8_t *ram, std::vector<uint8_t> font) {
outputter_.ram = ram;
@ -29,21 +29,17 @@ class CGA {
void run_for(Cycles cycles) {
// Input rate is the PIT rate of 1,193,182 Hz.
// MDA is actually clocked at 16.257 MHz; which is treated internally as 1,806,333.333333333333333... Hz
//
// The GCD of those two numbers is... 2. Oh well.
// I _think_ the MDA's CRTC is clocked at 14/9ths the PIT clock.
// Do that conversion here.
full_clock_ += 8'128'500 * cycles.as<int>();
crtc_.run_for(Cycles(full_clock_ / (596'591 * 9)));
full_clock_ %= (596'591 * 9);
// CGA is clocked at the real oscillator rate of 14 times that.
// But there's also an internal divide by 8 to align to the fetch clock.
full_clock_ += 7 * cycles.as<int>();
crtc_.run_for(Cycles(full_clock_ / 4));
full_clock_ %= 4;
}
template <int address>
void write(uint8_t value) {
if constexpr (address & 0x8) {
outputter_.set_control(value);
outputter_.set_mode(value);
} else {
if constexpr (address & 0x1) {
crtc_.set_register(value);
@ -55,10 +51,17 @@ class CGA {
template <int address>
uint8_t read() {
if constexpr (address & 0x8) {
return outputter_.control();
} else {
return crtc_.get_register();
switch(address) {
default: return crtc_.get_register();
case 0xa:
return
// b3: 1 => in vsync; 0 => not;
// b2: 1 => light pen switch is off;
// b1: 1 => positive edge from light pen has set trigger;
// b0: 1 => safe to write to VRAM now without causing snow.
(crtc_.get_bus_state().vsync ? 0b1001 : 0b0000) |
(crtc_.get_bus_state().hsync ? 0b0001 : 0b0000) |
0b0100;
}
}
@ -69,25 +72,33 @@ class CGA {
}
Outputs::Display::ScanStatus get_scaled_scan_status() const {
return outputter_.crt.get_scaled_scan_status() * 596591.0f / 8128500.0f;
return outputter_.crt.get_scaled_scan_status() * 4.0f / (7.0f * 8.0f);
}
private:
struct CRTCOutputter {
CRTCOutputter() :
crt(882, 9, 370, 3, Outputs::Display::InputDataType::Red2Green2Blue2)
// TODO: really this should be a Luminance8 and set an appropriate modal tint colour;
// consider whether that's worth building into the scan target.
crt(912, 8, 262, 3, Outputs::Display::InputDataType::Red2Green2Blue2)
{
// crt.set_visible_area(Outputs::Display::Rect(0.1072f, 0.1f, 0.842105263157895f, 0.842105263157895f));
crt.set_display_type(Outputs::Display::DisplayType::RGB);
}
void set_control(uint8_t control) {
// b0: 'high resolution' (probably breaks if not 1)
// b3: video enable
void set_mode(uint8_t control) {
// b5: enable blink
// b4: 1 => 640x200 graphics
// b3: video enable
// b2: 1 => monochrome
// b1: 1 => 320x200 graphics; 0 => text
// b0: 1 => 80-column text; 0 => 40
control_ = control;
if(control & 0x2) {
mode_ = (control & 0x10) ? Mode::Pixels640 : Mode::Pixels320;
} else {
mode_ = (control & 0x01) ? Mode::Text80 : Mode::Text40;
}
}
uint8_t control() {
@ -214,6 +225,10 @@ class CGA {
std::vector<uint8_t> font;
uint8_t control_ = 0;
enum class Mode {
Pixels320, Pixels640, Text80, Text40,
} mode_ = Mode::Text80;
} outputter_;
Motorola::CRTC::CRTC6845<CRTCOutputter, Motorola::CRTC::CursorType::MDA> crtc_;

1
Machines/Utility/ROMCatalogue.cpp
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@ -573,6 +573,7 @@ Description::Description(Name name) {
case Name::PCCompatiblePhoenix80286BIOS:
*this = Description(name, "PCCompatible", "Phoenix 80286 BIOS 3.05", "Phoenix 80286 ROM BIOS Version 3.05.bin", 32 * 1024, 0x8d0d318au);
break;
case Name::PCCompatibleCGAFont: /* TODO */
case Name::PCCompatibleMDAFont:
*this = Description(name, "PCCompatible", "IBM's MDA font", "EUMDA9.F14", 14 * 256, 0x7754882au);
break;

1
Machines/Utility/ROMCatalogue.hpp
View File

@ -136,6 +136,7 @@ enum Name {
PCCompatibleGLaBIOS,
PCCompatiblePhoenix80286BIOS,
PCCompatibleMDAFont,
PCCompatibleCGAFont,
// Sinclair QL.
SinclairQLJS,