// --- ---------- ------------------------------------------------------------
// JLH 06/15/2006 Added changelog ;-)
// JLH 06/15/2006 Switched over to timeslice execution code
+// JLH 07/15/2009 Solved problem with DEMO mode (IRQ handling)
//
#include "SDL.h"
#include "dis6809.h"
#include "dis6808.h"
-#define __DEBUG__
+//#define __DEBUG__
+//#define LOG_PIA1_IO
using namespace std;
V6808REGS soundCPU;
uint8 color[16];
uint32 palette[256];
+bool paletteDirty = false;
// Local variables
static bool running = true; // Machine running state flag...
static uint32 startTicks;
static uint8 * keys; // SDL raw keyboard matrix
+static uint64 clockFrameStart; // V6809 clock at the start of the frame
// Local timer callback functions
// 6809 memory functions
//
+#ifdef LOG_PIA1_IO
+char piaRegsName[4][10] = { "PORTA", "PACTL", "PORTB", "PBCTL" };
+#endif
uint8 RdMem6809(uint16 addr)
{
uint8 b;
b = grom[addr];
}
-//Is $C80E COUNT240? Hmm... No.
+ // A wee kludge (though I doubt it reads from anywhere other than $CB00)...
+ if ((addr & 0xFF00) == 0xCB00)
+#if 0
+ b = gram[0xCB00] & 0xFC; // Only bits 2-7 are connected...
+#else
+ {
+//Interesting, this code ALSO fucks up the demo...
+//Except when the correct code is called in the scanline callback function...
+ uint32 elapsedCycles = (uint32)(GetCurrentV6809Clock() - clockFrameStart);
+ uint32 scanline = (uint32)(((double)elapsedCycles * M6809_CYCLE_IN_USEC) / 65.10416666666667);
+//Changes here don't seem to do much...
+// uint32 scanline = (uint32)(((double)elapsedCycles * M6809_CYCLE_IN_USEC) / 70.0);
+ b = (uint8)scanline & 0xFC; // Only bits 2-7 are connected...
+ }
+#endif
+
+ // More kludge...
+ if ((addr == 0xC80C) && (gram[0xC80D] & 0x04)) // Read PORTA and DDR is set to Output
+ {
+ ClearLine(V6809_ASSERT_LINE_IRQ); // Then clear the IRQ
+//OK, this ALSO fucks up the execution of the demo...
+// mainCPU.cpuFlags &= ~V6809_ASSERT_LINE_IRQ; // Then clear the IRQ
+ }
+
+ if ((addr == 0xC80E) && (gram[0xC80F] & 0x04)) // Read PORTB and DDR is set to Output
+ {
+ ClearLine(V6809_ASSERT_LINE_IRQ); // Then clear the IRQ
+//OK, this ALSO fucks up the execution of the demo...
+// mainCPU.cpuFlags &= ~V6809_ASSERT_LINE_IRQ; // Then clear the IRQ
+ }
//temp...
/*extern uint16 pcr;
//if (addr >= 0xC000 && addr <= 0xCBFF)
if (addr == 0x9C59)
WriteLog("RdMem: Reading address %04X [=%02X, PC=%04X]\n", addr, b, pcr);//*/
-/*if (addr >= 0xC80D && addr <= 0xC80F)
- WriteLog("V6809 RdMem: Reading address %04X [=%02X, PC=%04X]\n", addr, b, mainCPU.pc);//*/
-
+#ifdef LOG_PIA1_IO
+/*if (addr >= 0xC80C && addr <= 0xC80F)
+ WriteLog("V6809 RdMem: Reading PIA (%s) address %04X [<-%02X, PC=%04X]\n", piaRegsName[addr&0x03], addr, b, GetCurrentV6809PC());//*/
+#endif
return b;
}
gram[addr] = b;
- if (addr > 0x0006 && addr < 0x97F7) // 304 pixels 152-128=24-16=8
+ if (addr >= 0x0006 && addr < 0x97F7) // 304 pixels 152-128=24-16=8
{
// NOTE: Screen was 304 x 256, but we truncate the vertical dimension here...
uint16 sx = (addr >> 7) & 0x01FE, sy = addr & 0x00FF;
if (sy > 5 && sy < 246)
{
uint32 saddr = 8 + sx + ((sy - 6) * 320); // Calc screen address
-//Hmm. This approach won't work with palette color cycling...
-#if 0
- scrBuffer[saddr + 0] = b >> 4;
- scrBuffer[saddr + 1] = b & 0x0F;
-#else
scrBuffer[saddr + 0] = palette[color[b >> 4]];
scrBuffer[saddr + 1] = palette[color[b & 0x0F]];
-#endif
}
}
else if (addr >= 0xC000 && addr <= 0xC00F)
-//Let's see if we can fix the color cycling here... [DONE]
-#if 0
- color[addr - 0xC000] = b; // color[] from VIDEO.CPP (not any more!)
-#else
{
// A better strategy here would probably be to set a flag when the color register changes,
// then change it before doing the render.
// ALSO: This approach doesn't take the color to the edges of the screen
+//#warning "This should only touch memory right before a render. !!! FIX !!!"
+//Now it does. :-)
color[addr - 0xC000] = b;
- for(uint32 addr=0x0007; addr<0x97F7; addr++)
+#if 0
+ for(uint32 addr=0x0006; addr<0x97F7; addr++)
{
uint16 sx = (addr >> 7) & 0x01FE, sy = addr & 0x00FF;
scrBuffer[saddr + 1] = palette[color[sb & 0x0F]];
}
}
- }
+#else
+ paletteDirty = true;
#endif
+ }
else if (addr == 0xC80E)
{
sram[0x0402] = b; // Connect PIAs in 6809 & 6808
soundCPU.cpuFlags |= V6808_ASSERT_LINE_IRQ; // Start sound IRQ
}
+
+#ifdef LOG_PIA1_IO
+//if (addr >= 0xC80C && addr <= 0xC80F)
+if (addr == 0xC80D)
+ WriteLog("V6809 WrMem: Writing PIA (%s) address %04X [->%02X, PC=%04X]\n", piaRegsName[addr&0x03], addr, b, GetCurrentV6809PC());//*/
+#endif
}
//
// A total guess, but let's try it...
//It probably depends on how the PIA is configured, so this is most likely wrong.
+// It is wrong: IRQs are cleared on PIA PORTx reads!
// if (addr == 0x0401)
// soundCPU.cpuFlags &= ~V6808_ASSERT_LINE_IRQ;
}
//
// Load a file into RAM/ROM image space
//
-bool LoadImg(char * filename, uint8 * ram, int size)
+bool LoadImg(const char * filename, uint8 * ram, int size)
{
FILE * fp = fopen(filename, "rb");
if (fp == NULL)
return false;
- fread(ram, 1, size, fp);
+ size_t ignoredResult = fread(ram, 1, size, fp);
fclose(fp);
return true;
if (fp != NULL)
{
- fwrite(gram + 0xCC00, 1, 1024, fp);
+ size_t ignoredResult = fwrite(gram + 0xCC00, 1, 1024, fp);
fclose(fp);
}
else
return false;
// This is kinda crappy--we don't do any sanity checking here!!!
- fread(gram, 1, 0x10000, fp);
- fread(sram, 1, 0x10000, fp);
- fread(&mainCPU, 1, sizeof(V6809REGS), fp);
- fread(&soundCPU, 1, sizeof(V6808REGS), fp);
+ size_t ignoredResult = fread(gram, 1, 0x10000, fp);
+ ignoredResult = fread(sram, 1, 0x10000, fp);
+ ignoredResult = fread(&mainCPU, 1, sizeof(V6809REGS), fp);
+ ignoredResult = fread(&soundCPU, 1, sizeof(V6808REGS), fp);
fclose(fp);
- for(int i=0x0006; i<0x97F8; i++) // Set up backbuffer... ;-)
- WrMem6809(i, gram[i]);
+// for(int i=0x0006; i<0x97F8; i++) // Set up backbuffer... ;-)
+// WrMem6809(i, gram[i]);
+
+ paletteDirty = true; // Set up backbuffer...
mainCPU.RdMem = RdMem6809; // Make sure our function pointers are
mainCPU.WrMem = WrMem6809; // pointing to the right places!
soundCPU.RdMem = RdMem6808;
soundCPU.WrMem = WrMem6808;
+ mainCPU.clock = 0; // Zero out our clocks...
+ soundCPU.clock = 0;
return true;
}
if (fp != NULL)
{
- fwrite(gram, 1, 0x10000, fp);
- fwrite(sram, 1, 0x10000, fp);
- fwrite(&mainCPU, 1, sizeof(V6809REGS), fp);
- fwrite(&soundCPU, 1, sizeof(V6808REGS), fp);
+ size_t ignoredResult = fwrite(gram, 1, 0x10000, fp);
+ ignoredResult = fwrite(sram, 1, 0x10000, fp);
+ ignoredResult = fwrite(&mainCPU, 1, sizeof(V6809REGS), fp);
+ ignoredResult = fwrite(&soundCPU, 1, sizeof(V6808REGS), fp);
fclose(fp);
}
else
{
InitLog("stargem2.log");
WriteLog("StarGem2 - A portable Stargate emulator by James L. Hammons\n");
+ WriteLog("(C) 2009 Underground Software\n\n");
LoadSettings();
#endif
// Zero out memory
- for(long i=0; i<0x10000; i++)
- gram[i] = grom[i] = sram[i] = srom[i] = 0;
+ memset(gram, 0, 0x10000);
+ memset(grom, 0, 0x10000);
+ memset(sram, 0, 0x10000);
+ memset(srom, 0, 0x10000);
// Set up V6809 & V6808 execution contexts
-
- memset(&mainCPU, sizeof(V6809REGS), 0);
+
+ memset(&mainCPU, 0, sizeof(V6809REGS));
mainCPU.RdMem = RdMem6809;
mainCPU.WrMem = WrMem6809;
mainCPU.cpuFlags |= V6809_ASSERT_LINE_RESET;
- memset(&soundCPU, sizeof(V6808REGS), 0);
+ memset(&soundCPU, 0, sizeof(V6808REGS));
soundCPU.RdMem = RdMem6808;
soundCPU.WrMem = WrMem6808;
soundCPU.cpuFlags |= V6808_ASSERT_LINE_RESET;
if (i > 8)
baseAddress += 0x4000;
-#if 0
-WriteLog("Loading ROM image '%s' at $%04X...\n", ROMs[i], baseAddress);
-#endif
-// if (!LoadImg(ROMs[i], grom + (i * 0x1000), 0x1000))
if (!LoadImg(ROMs[i], grom + baseAddress, 0x1000))
{
WriteLog("Could not open file '%s'!\n", ROMs[i]);
WriteLog("About to intialize audio...\n");
SoundInit();
-// uint8 * keys = SDL_GetKeyState(NULL);
keys = SDL_GetKeyState(NULL);
-
-// running = true; // Set running status...
srom[0xF800] = 0x37; // Fix checksum so ST works...
-
-#if 0
-
-//kludge...
-//This didn't work--it still acted like the old way (interrupt @ VC = 0)
-//gram[0xCB00] = 64*3;
-
- WriteLog("Entering main loop...\n");
- while (running)
- {
- SDL_PumpEvents(); // Force key events into the buffer.
- gram[0xC804] = gram[0xC806] = gram[0xC80C] = 0; // Reset PIA ports...
-
- if (keys[SDLK_ESCAPE])
- running = false; // ESC to exit...
-
- if (keys[SDLK_SEMICOLON])
- gram[0xC804] |= 0x01; // Fire (;)
- if (keys[SDLK_l])
- gram[0xC804] |= 0x02; // Thrust (L)
- if (keys[SDLK_SPACE])
- gram[0xC804] |= 0x04; // Smart Bomb (space)
- if (keys[SDLK_BACKSPACE])
- gram[0xC804] |= 0x08; // Hyperspace (BkSp)
- if (keys[SDLK_2])
- gram[0xC804] |= 0x10; // Two Player Start (2)
- if (keys[SDLK_1])
- gram[0xC804] |= 0x20; // One Player Start (1)
- if (keys[SDLK_RETURN])
- gram[0xC804] |= 0x40; // Reverse (Enter)
- if (keys[SDLK_f])
- gram[0xC804] |= 0x80; // Down (F)
-
- if (keys[SDLK_r])
- gram[0xC806] |= 0x01; // Up (R)
- if (keys[SDLK_a])
- gram[0xC806] |= 0x02; // Inviso (A)
-
- if (keys[SDLK_F1])
- gram[0xC80C] |= 0x01; // Auto up (F1)
- if (keys[SDLK_F2])
- gram[0xC80C] |= 0x02; // Advance (F2)
- if (keys[SDLK_5])
- gram[0xC80C] |= 0x04; // Right Coin (5)
- if (keys[SDLK_F3])
- gram[0xC80C] |= 0x08; // High Score Reset (F3)
- if (keys[SDLK_3])
- gram[0xC80C] |= 0x10; // Left Coin (3)
- if (keys[SDLK_4])
- gram[0xC80C] |= 0x20; // Center Coin (4)
- if (keys[SDLK_F4])
- gram[0xC80C] |= 0x40; // Slam Switch (F4)
-
- if (keys[SDLK_F5]) // Sound CPU self-test (F5)
- soundCPU.cpuFlags |= V6808_ASSERT_LINE_NMI;
- if (keys[SDLK_F6]) // Reset the 6808 (F6)
- soundCPU.cpuFlags |= V6808_ASSERT_LINE_RESET;
-
-/*
-$CB00 is scanline counter, bits 2-7 (1 frame/240 =69.44... usec)
-
-Some places of interest to look at:
-
-RdMem: Reading address C80E [=0C, PC=15C3] <- Inside interrupt (read, then discarded)...
-RdMem: Reading address CB00 [=43, PC=15C6] <- interrupt
-RdMem: Reading address C80C [=00, PC=0758] <- input (?)
-RdMem: Reading address C80C [=00, PC=07B9] <- input (?)
-RdMem: Reading address C806 [=00, PC=078C] <- input
-RdMem: Reading address C804 [=00, PC=2679] <- input
-*/
- uint32 startTicks = SDL_GetTicks();
-// long video_clk = 0;
-// gram[0xCB00] = 0;
-
-/*
-//This is where the interrupt mask is restored in CC... Hmm...
-//This enables interrupts *after* the previous interrupt has occurred... Hmm.
-//Could $C80F (rom_pia_ctrlb) be the IRQ inhibit? Yes, it is!
-
- // the IRQ signal comes into CB1, and is set to VA11
- pia_1_cb1_w(0, scanline & 0x20);
-...
- // the COUNT240 signal comes into CA1, and is set to the logical AND of VA10-VA13
- pia_1_ca1_w(0, 0);
-...
- // the COUNT240 signal comes into CA1, and is set to the logical AND of VA10-VA13
- pia_1_ca1_w(0, 1);
-*/
-
-//WriteLog("--> Start of frame...\n");
- for(int i=0; i<3; i++)
- {
-//Not sure, but this *might* fix IRQ problem...
-//Checking the PIA IRQ mask for an IRQ seems to work OK. Now if only the timing elsewhere was right...
- if (gram[0xC80F] & 0x01)
- mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;//*/
-
- Execute6809(&mainCPU, 4000);
- mainCPU.clock -= 4000; // Remove 4K ticks from clock (in case it overflowed)
-//Not sure, but this *might* fix IRQ problem...
-//Checking the PIA IRQ mask for an IRQ seems to work OK. Now if only the timing elsewhere was right...
-/* if (gram[0xC80F] & 0x01)
- mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;//*/
-
- gram[0xCB00] += 64; // Update video counter...
- }
-
-//Hmm.
-/*if (gram[0xC80E] & 0x01)
- mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;//*/
-//48 lines... (+ 16)
-//gram[0xCB00] = 0;
- Execute6809(&mainCPU, 3000);
- mainCPU.clock -= 3000; // Remove 3K ticks from clock (in case it overflowed)
-//Not sure, but this *might* fix IRQ problem...
-//if (gram[0xC80F] & 0x01)
-//This isn't the right port on the PIA, but it does seem to make it through the demo now...
-//Lesse if this works... Seems to!
- if (gram[0xC80D] & 0x01) // Do COUNT240 IRQ (if enabled!)
- mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;
-
-/*if (gram[0xC80F] & 0x01)
- mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;
-gram[0xCB00] = 0; //*/
-
- gram[0xCB00] += 48; // Update video counter...
-
- Execute6809(&mainCPU, 1000);
- mainCPU.clock -= 1000; // Remove 1K ticks from clock (in case it overflowed)
-//Eh?
-//Ok, this is the interrupt it's looking for, but still...
-//if (gram[0xC80F] & 0x01)
-// mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;
-
- gram[0xCB00] += 16; // Update video counter...
-
-// RenderScreenBuffer();
- RenderScreenBuffer2(); // 1 frame = 16667 cycles
-// WriteLog("Main: Rendered back buffer. [6809 PC=%04X]\n", pcr);
-
- Execute6809(&mainCPU, 667); // Do QnD VBLANK
-
- // 1/60 sec = ? ms (16.6 ms)
- while (SDL_GetTicks() - startTicks < 16); // Wait for next frame...
-
-//kludge, temp...
-//Very interesting! It's the palette rotation that's slowing it down!
-//Fixed now, but this allows the color rotation while the wrong timing is in effect...
-/*for(int i=0; i<16; i++)
- WrMem(0xC000 + i, gram[0x9C26 + i]);//*/
- }
-
-/*uint16 pc = 0x15BA;
-for(int i=0; i<200; i++)
-//while (pc < 0x9000)
- pc += Decode6809(pc);//*/
-
-#else
-
running = true; // Set running status...
InitializeEventList(); // Clear the event list before we use it...
SetCallbackTime(FrameCallback, 16666.66666667); // Set frame to fire at 1/60 s interval
-// SetCallbackTime(BlinkTimer, 250000); // Set up blinking at 1/4 s intervals
- SetCallbackTime(ScanlineCallback, 520.83333334); // Set scanline callback at 1/32 of frame
-// SetCallbackTime(ScanlineCallback, 520.83333334*32.00); // Set scanline callback at 1/32 of frame
+// SetCallbackTime(ScanlineCallback, 520.83333334); // Set scanline callback at 1/32 of frame
+ SetCallbackTime(ScanlineCallback, 520.83333334/2.0); // Set scanline callback at 1/64 of frame
+ clockFrameStart = mainCPU.clock;
startTicks = SDL_GetTicks();
WriteLog("Entering main loop...\n");
Execute6809(&mainCPU, USEC_TO_M6809_CYCLES(timeToNextEvent));
//We MUST remove a frame's worth of time in order for the CPU to function... !!! FIX !!!
//(Fix so that this is not a requirement!)
- mainCPU.clock -= USEC_TO_M6809_CYCLES(timeToNextEvent);
+//Very odd... Execution seems to fuck up when using a 64-bit clock...
+//(i.e., when this is commented out!)
+// mainCPU.clock -= USEC_TO_M6809_CYCLES(timeToNextEvent);
HandleNextEvent();
}
pc += Decode6809(pc);
WriteLog("\n");
}//*/
-#endif
-
#endif
SoundDone();
if (keys[SDLK_F6]) // Reset the 6808 (F6)
soundCPU.cpuFlags |= V6808_ASSERT_LINE_RESET;
- RenderScreenBuffer2(); // 1 frame = 1/60 sec ~ 16667 cycles
+ if (paletteDirty)
+ {
+ for(uint32 addr=0x0006; addr<0x97F7; addr++)
+ {
+ uint16 sx = (addr >> 7) & 0x01FE, sy = addr & 0x00FF;
+
+ if (sy > 5 && sy < 246)
+ {
+ uint32 saddr = 8 + sx + ((sy - 6) * 320); // Calc screen address
+ uint8 sb = gram[addr];
+
+ scrBuffer[saddr + 0] = palette[color[sb >> 4]];
+ scrBuffer[saddr + 1] = palette[color[sb & 0x0F]];
+ }
+ }
+
+ paletteDirty = false;
+ }
+
+ RenderScreenBuffer(); // 1 frame = 1/60 sec ~ 16667 cycles
SetCallbackTime(FrameCallback, 16666.66666667);
+ clockFrameStart = mainCPU.clock;
+
+ // Wait for next frame...
+ while (SDL_GetTicks() - startTicks < 16)
+ SDL_Delay(1);
- while (SDL_GetTicks() - startTicks < 16); // Wait for next frame...
startTicks = SDL_GetTicks();
}
static void ScanlineCallback(void)
{
-// CA1 of PIA 1 maps to $C80C-F... <-- Count240 is in PIA1...
-// What about COUNT240???
-
-//wil wok? Yes, but still screws up on the demo...
-/* if (gram[0xCB00] & 0x20)
- if (gram[0xC80F] & 0x01)
- mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;//*/
+#if 0
if ((gram[0xCB00] & 0x20) && (gram[0xC80F] & 0x01))
mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;//*/
+#else
+ mainCPU.cpuFlags &= ~V6809_ASSERT_LINE_IRQ;
-//Is $C80E COUNT240? Hmm... Doesn't seem to be. Bleh.
-/* if (gram[0xCB00] >= 240)
- gram[0xC80E] = 0xFF;
- else
- gram[0xC80E] = 0x00;//*/
-// gram[0xC80E] = (gram[0xCB00] >= 240 ? 0xFF : 0x00);
+ if ((RdMem6809(0xCB00) & 0x20) && (gram[0xC80F] & 0x01))
+ mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;//*/
+#endif
+
+/*
+The problem is that this is already asserted above, by virtue of the fact that
+240 = $F0 = bit 5 is set! So this does nothing! So obviously, the above IRQ assertion
+is wrong--just need to figure out how the write of $20 and $00 affects the PBCTRL in the PIA.
+It looks like Stargate never asserts the COUNT240 IRQ, and could be because of the above...
+
+Apparently, COUNT240 is unimportant, at least as far as STARGATE is concerned...
+*/
+// if ((gram[0xCB00] >= 240) && (gram[0xC80D] & 0x09)) // Do COUNT240 IRQ (if enabled!)
+// mainCPU.cpuFlags |= V6809_ASSERT_LINE_IRQ;
- gram[0xCB00] += 8; // Update video counter...
+ // This should set everything between $CB00-CBFF...
+// gram[0xCB00] += 8; // Update video counter...
+ gram[0xCB00] += 4; // Update video counter...
- SetCallbackTime(ScanlineCallback, 520.83333334); // Set scanline callback at 1/32 of frame
+// SetCallbackTime(ScanlineCallback, 520.83333334); // Set scanline callback at 1/32 of frame
+ SetCallbackTime(ScanlineCallback, 520.83333334/2.0); // Set scanline callback at 1/64 of frame
}
*/
+#if 0
+
+#define PIA_IRQ1 (0x80)
+#define PIA_IRQ2 (0x40)
+
+#define IRQ1_ENABLED(c) ( (((c) >> 0) & 0x01))
+#define C1_LOW_TO_HIGH(c) ( (((c) >> 1) & 0x01))
+#define C1_HIGH_TO_LOW(c) (!(((c) >> 1) & 0x01))
+#define OUTPUT_SELECTED(c) ( (((c) >> 2) & 0x01))
+#define IRQ2_ENABLED(c) ( (((c) >> 3) & 0x01))
+#define STROBE_E_RESET(c) ( (((c) >> 3) & 0x01))
+#define STROBE_C1_RESET(c) (!(((c) >> 3) & 0x01))
+#define C2_SET(c) ( (((c) >> 3) & 0x01))
+#define C2_LOW_TO_HIGH(c) ( (((c) >> 4) & 0x01))
+#define C2_HIGH_TO_LOW(c) (!(((c) >> 4) & 0x01))
+#define C2_SET_MODE(c) ( (((c) >> 4) & 0x01))
+#define C2_STROBE_MODE(c) (!(((c) >> 4) & 0x01))
+#define C2_OUTPUT(c) ( (((c) >> 5) & 0x01))
+#define C2_INPUT(c) (!(((c) >> 5) & 0x01))
+
+WRITE8_DEVICE_HANDLER( pia6821_ca1_w )
+{
+ pia6821_state *p = get_token(device);
+
+ /* limit the data to 0 or 1 */
+ data = data ? TRUE : FALSE;
+
+ LOG(("PIA #%s: set input CA1 = %d\n", device->tag, data));
+
+ /* the new state has caused a transition */
+ if ((p->in_ca1 != data) &&
+ ((data && C1_LOW_TO_HIGH(p->ctl_a)) || (!data && C1_HIGH_TO_LOW(p->ctl_a))))
+ {
+ LOG(("PIA #%s: CA1 triggering\n", device->tag));
+
+ /* mark the IRQ */
+ p->irq_a1 = TRUE;
+
+ /* update externals */
+ update_interrupts(device);
+
+ /* CA2 is configured as output and in read strobe mode and cleared by a CA1 transition */
+ if (C2_OUTPUT(p->ctl_a) && C2_STROBE_MODE(p->ctl_a) && STROBE_C1_RESET(p->ctl_a))
+ set_out_ca2(device, TRUE);
+ }
+
+ /* set the new value for CA1 */
+ p->in_ca1 = data;
+ p->in_ca1_pushed = TRUE;
+}
+
+WRITE8_DEVICE_HANDLER( pia6821_cb1_w )
+{
+ pia6821_state *p = get_token(device);
+
+ /* limit the data to 0 or 1 */
+ data = data ? 1 : 0;
+
+ LOG(("PIA #%s: set input CB1 = %d\n", device->tag, data));
+
+ /* the new state has caused a transition */
+ if ((p->in_cb1 != data) &&
+ ((data && C1_LOW_TO_HIGH(p->ctl_b)) || (!data && C1_HIGH_TO_LOW(p->ctl_b))))
+ {
+ LOG(("PIA #%s: CB1 triggering\n", device->tag));
+
+ /* mark the IRQ */
+ p->irq_b1 = 1;
+
+ /* update externals */
+ update_interrupts(device);
+
+ /* If CB2 is configured as a write-strobe output which is reset by a CB1
+ transition, this reset will only happen when a read from port B implicitly
+ clears the IRQ B1 flag. So we handle the CB2 reset there. Note that this
+ is different from what happens with port A. */
+ }
+
+ /* set the new value for CB1 */
+ p->in_cb1 = data;
+ p->in_cb1_pushed = TRUE;
+}
+
+static void update_interrupts(const device_config *device)
+{
+ pia6821_state *p = get_token(device);
+ int new_state;
+
+ /* start with IRQ A */
+ new_state = (p->irq_a1 && IRQ1_ENABLED(p->ctl_a)) || (p->irq_a2 && IRQ2_ENABLED(p->ctl_a));
+
+ if (new_state != p->irq_a_state)
+ {
+ p->irq_a_state = new_state;
+ devcb_call_write_line(&p->irq_a_func, p->irq_a_state);
+ }
+
+ /* then do IRQ B */
+ new_state = (p->irq_b1 && IRQ1_ENABLED(p->ctl_b)) || (p->irq_b2 && IRQ2_ENABLED(p->ctl_b));
+
+ if (new_state != p->irq_b_state)
+ {
+ p->irq_b_state = new_state;
+ devcb_call_write_line(&p->irq_b_func, p->irq_b_state);
+ }
+}
+
+static void control_b_w(const device_config *device, UINT8 data)
+{
+ pia6821_state *p = get_token(device);
+ int temp;
+
+ /* bit 7 and 6 are read only */
+ data &= 0x3f;
+
+ LOG(("PIA #%s: control B write = %02X\n", device->tag, data));
+
+ /* update the control register */
+ p->ctl_b = data;
+
+ if (C2_SET_MODE(p->ctl_b))
+ /* set/reset mode - bit value determines the new output */
+ temp = C2_SET(p->ctl_b);
+ else
+ /* strobe mode - output is always high unless strobed */
+ temp = TRUE;
+
+ set_out_cb2(device, temp);
+
+ /* update externals */
+ update_interrupts(device);
+}
+
+static void control_a_w(const device_config *device, UINT8 data)
+{
+ pia6821_state *p = get_token(device);
+
+ /* bit 7 and 6 are read only */
+ data &= 0x3f;
+
+ LOG(("PIA #%s: control A write = %02X\n", device->tag, data));
+
+ /* update the control register */
+ p->ctl_a = data;
+
+ /* CA2 is configured as output */
+ if (C2_OUTPUT(p->ctl_a))
+ {
+ int temp;
+
+ if (C2_SET_MODE(p->ctl_a))
+ /* set/reset mode - bit value determines the new output */
+ temp = C2_SET(p->ctl_a);
+ else
+ /* strobe mode - output is always high unless strobed */
+ temp = TRUE;
+
+ set_out_ca2(device, temp);
+ }
+
+ /* update externals */
+ update_interrupts(device);
+}
+
+
+CTRL REGISTER:
+
+B7 B6 B5 B4 B3 B2 B1 B0
+--------------------------------------------------
+IRQA(B)1 IRQA(B)2 CA(B)2 Ctrl DDR CA(B)1 Ctrl
+
+Bits 6 & 7 are RO. IRQs are cleared on read of PORTA when not in DDR mode
+DDR: 0: DDR selected, 1: Output register selected
+CA1(CB1) Ctrl: B0: 0/1 Dis/enable interrupt IRQA(B)
+ B1: 0/1 IRQ set by Hi-to-Lo/Lo-to-Hi transition on CA(B)1
+CA2(CB2) Ctrl: If B5==0, B4 & B3 are similar to B1 & B0
+
+Entering main loop...
+V6809 WrMem: Writing PIA (PACTL) address C80D [->00, PC=F4DC] --> Set DDR on PORTA, IRQs off
+V6809 WrMem: Writing PIA (PORTA) address C80C [->00, PC=F4DF] --> Set DDR to all input on PORTA
+V6809 WrMem: Writing PIA (PACTL) address C80D [->3C, PC=F4E4] --> Set Output on PORTA, Set CA2 = 1, disable IRQA1
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->00, PC=F4E7] --> Set DDR on PORTB, IRQs off
+V6809 WrMem: Writing PIA (PORTB) address C80E [->C0, PC=F4EC] --> Set DDR to output on 6,7 input on 0-5 on PORTB
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->3C, PC=F4F1] --> Set Output on PORTA, Set CB2 = 1, disable IRQB1
+V6809 WrMem: Writing PIA (PORTB) address C80E [->C0, PC=F4F6] --> Send 1s on bits 6 & 7 on PORTB
+V6809 WrMem: Writing PIA (PACTL) address C80D [->34, PC=F523] --> Set Output on PORTA, Set CA2 = 0, disable IRQA1
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=F526] --> Set Output on PORTB, Set CB2 = 0, disable IRQB1
+V6809 WrMem: Writing PIA (PORTB) address C80E [->00, PC=F529] --> Send 0s on bits 6 & 7 on PORTB
+V6809 WrMem: Writing PIA (PORTA) address C80C [->00, PC=6076] --> Do nothing
+V6809 WrMem: Writing PIA (PACTL) address C80D [->00, PC=6076] --> Set DDR on PORTA, IRQs off
+V6809 WrMem: Writing PIA (PORTA) address C80C [->00, PC=607B] --> Set DDR to all input on PORTA
+V6809 WrMem: Writing PIA (PACTL) address C80D [->34, PC=607B] --> Set Output on PORTA, Set CA2 = 0, disable IRQA1
+V6809 WrMem: Writing PIA (PORTB) address C80E [->00, PC=6076] --> Send 0s on bits 6 & 7 on PORTB
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->00, PC=6076] --> Set DDR on PORTB, IRQs off
+V6809 WrMem: Writing PIA (PORTB) address C80E [->FF, PC=607B] --> Set DDR to all output on PORTB
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=607B] --> Set Output on PORTB, Set CB2 = 0, enable IRQB1
+V6809 WrMem: Writing PIA (PORTB) address C80E [->3F, PC=6088] --> Send $3F on PORTB
+V6809 WrMem: Writing PIA (PORTB) address C80E [->0C, PC=60DB] --> Send $0C on PORTB
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3] --> Set Output on PORTB, Set CB2 = 0, disable IRQB1
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6] --> Clear IRQBs
+ 6809 RdMem: Reading PIA (PORTA) address C80C [=00, PC=075B] --> Clear IRQAs
+ 6809 RdMem: Reading PIA (PORTA) address C80C [=00, PC=07B9] --> Clear IRQAs
+
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=1644] --> Set Output on PORTB, Set CB2 = 0, enable IRQB1
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3] --> Set Output on PORTB, Set CB2 = 0, disable IRQB1
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6] --> Clear IRQBs
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=1644]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3]
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=1644]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3]
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=1644]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3]
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=1644]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3]
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->35, PC=1644]
+V6809 WrMem: Writing PIA (PBCTL) address C80F [->34, PC=15C3]
+ 6809 RdMem: Reading PIA (PORTB) address C80E [=0C, PC=15C6]
+
+#endif