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M6801 changes: [Curt Coder]

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- added operating mode enum
- fixed port writes
- implemented SCI status follower bits
This commit is contained in:
Curt Coder 2011-01-20 17:17:08 +00:00
parent 3d748f0316
commit a17a148fa0
2 changed files with 202 additions and 107 deletions
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297
src/emu/cpu/m6800/m6800.c
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@ -53,20 +53,29 @@ TODO:
/*
Chip RAM NVRAM ROM SCI
-----------------------------------------------
MC6800 - - - no
MC6801 128 64 2K yes
MC68701 128 64 - yes
MC6803 128 64 - yes
MC6802 128 32 - no
MC6802NS 128 - - no
MC6808 - - - no
Chip RAM NVRAM ROM SCI r15-f ports
-----------------------------------------------------------------
MC6800 - - - no no 4
MC6802 128 32 - no no 4
MC6802NS 128 - - no no 4
MC6808 - - - no no 4
MC6801 128 64 2K yes no 4
MC68701 128 64 - yes no 4
MC6803 128 64 - yes no 4
HD6301 128 - 4K yes
HD63701 192 - 4K yes
HD6303 128 - - yes
HD6801 128 64 2K yes
MC6801U4 192 32 4K yes yes 4
MC6803U4 192 32 - yes yes 4
HD6801 128 64 2K yes no 4
HD6301V 128 - 4K yes no 4
HD63701V 192 - 4K yes no 4
HD6303R 128 - - yes no 4
HD6301X 192 - 4K yes yes 6
HD6301Y 256 - 16K yes yes 6
HD6303X 192 - - yes yes 6
HD6303Y 256 - - yes yes 6
NSC8105
MS2010-A
@ -142,14 +151,14 @@ struct _m6800_state
int clock;
UINT8 trcsr, rmcr, rdr, tdr, rsr, tsr;
int rxbits, txbits, txstate, trcsr_read, tx;
int rxbits, txbits, txstate, trcsr_read_tdre, trcsr_read_orfe, trcsr_read_rdrf, tx;
int port2_written;
int icount;
int latch09;
PAIR timer_over;
emu_timer *m6800_rx_timer;
emu_timer *m6800_tx_timer;
emu_timer *sci_timer;
PAIR ea; /* effective address */
};
@ -271,14 +280,14 @@ static UINT32 timer_next;
#define M6800_TRCSR_RDRF 0x80 // Receive Data Register Full
#define M6800_TRCSR_ORFE 0x40 // Over Run Framing Error
#define M6800_TRCSR_TDRE 0x20 // Transmit Data Register Empty
#define M6800_TRCSR_RIE 0x10 // Receive Interrupt Enable
#define M6800_TRCSR_RIE 0x10 // Receive Interrupt Enable
#define M6800_TRCSR_RE 0x08 // Receive Enable
#define M6800_TRCSR_TIE 0x04 // Transmit Interrupt Enable
#define M6800_TRCSR_TIE 0x04 // Transmit Interrupt Enable
#define M6800_TRCSR_TE 0x02 // Transmit Enable
#define M6800_TRCSR_WU 0x01 // Wake Up
#define M6800_PORT2_IO4 0x10
#define M6800_PORT2_IO3 0x08
#define M6800_PORT2_IO4 0x10
#define M6800_PORT2_IO3 0x08
static const int M6800_RMCR_SS[] = { 16, 128, 1024, 4096 };
@ -587,6 +596,7 @@ static void m6800_check_irq2(m6800_state *cpustate)
((cpustate->trcsr & (M6800_TRCSR_RIE|M6800_TRCSR_ORFE)) == (M6800_TRCSR_RIE|M6800_TRCSR_ORFE)) ||
((cpustate->trcsr & (M6800_TRCSR_TIE|M6800_TRCSR_TDRE)) == (M6800_TRCSR_TIE|M6800_TRCSR_TDRE)))
{
//logerror("M6800 '%s' SCI interrupt\n", cpustate->device->tag());
TAKE_SCI;
}
}
@ -665,31 +675,66 @@ INLINE void increment_counter(m6800_state *cpustate, int amount)
check_timer_event(cpustate);
}
INLINE void set_rmcr(m6800_state *cpustate, UINT8 data)
{
if (cpustate->rmcr == data) return;
cpustate->rmcr = data;
switch ((cpustate->rmcr & M6800_RMCR_CC_MASK) >> 2)
{
case 0:
case 3: // not implemented
timer_enable(cpustate->sci_timer, 0);
break;
case 1:
case 2:
{
int divisor = M6800_RMCR_SS[cpustate->rmcr & M6800_RMCR_SS_MASK];
timer_adjust_periodic(cpustate->sci_timer, ATTOTIME_IN_HZ(cpustate->clock / divisor), 0, ATTOTIME_IN_HZ(cpustate->clock / divisor));
}
break;
}
}
INLINE void write_port2(m6800_state *cpustate)
{
if (!cpustate->port2_written) return;
UINT8 data = cpustate->port2_data;
UINT8 ddr = cpustate->port2_ddr & 0x1f;
if ((ddr != 0x1f) && ddr)
{
data = (cpustate->port2_data & ddr) | (ddr ^ 0xff);
}
if (cpustate->trcsr & M6800_TRCSR_TE)
{
data = (data & 0xef) | (cpustate->tx << 4);
}
data &= 0x1f;
cpustate->io->write_byte(M6803_PORT2, data);
}
/* include the opcode prototypes and function pointer tables */
#include "6800tbl.c"
/* include the opcode functions */
#include "6800ops.c"
static void m6800_tx(m6800_state *cpustate, int value)
{
cpustate->port2_data = (cpustate->port2_data & 0xef) | (value << 4);
if(cpustate->port2_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT2,cpustate->port2_data);
else
cpustate->io->write_byte(M6803_PORT2,(cpustate->port2_data & cpustate->port2_ddr)
| (cpustate->io->read_byte(M6803_PORT2) & (cpustate->port2_ddr ^ 0xff)));
}
static int m6800_rx(m6800_state *cpustate)
{
return (cpustate->io->read_byte(M6803_PORT2) & M6800_PORT2_IO3) >> 3;
}
static TIMER_CALLBACK(m6800_tx_tick)
static void serial_transmit(m6800_state *cpustate)
{
m6800_state *cpustate = (m6800_state *)ptr;
//logerror("M6800 '%s' Tx Tick\n", cpustate->device->tag());
if (cpustate->trcsr & M6800_TRCSR_TE)
{
@ -732,6 +777,8 @@ static TIMER_CALLBACK(m6800_tx_tick)
cpustate->tx = 0;
cpustate->txbits++;
//logerror("M6800 '%s' Transmit START Data %02x\n", cpustate->device->tag(), cpustate->tsr);
}
break;
@ -742,6 +789,8 @@ static TIMER_CALLBACK(m6800_tx_tick)
CHECK_IRQ_LINES(cpustate);
cpustate->txbits = M6800_SERIAL_START;
//logerror("M6800 '%s' Transmit STOP\n", cpustate->device->tag());
break;
default:
@ -751,45 +800,52 @@ static TIMER_CALLBACK(m6800_tx_tick)
// shift transmit register
cpustate->tsr >>= 1;
//logerror("M6800 '%s' Transmit Bit %u: %u\n", cpustate->device->tag(), cpustate->txbits, cpustate->tx);
cpustate->txbits++;
break;
}
break;
}
}
m6800_tx(cpustate, cpustate->tx);
cpustate->port2_written = 1;
write_port2(cpustate);
}
}
static TIMER_CALLBACK(m6800_rx_tick)
static void serial_receive(m6800_state *cpustate)
{
m6800_state *cpustate = (m6800_state *)ptr;
//logerror("M6800 '%s' Rx Tick TRCSR %02x bits %u check %02x\n", cpustate->device->tag(), cpustate->trcsr, cpustate->rxbits, cpustate->trcsr & M6800_TRCSR_RE);
if (cpustate->trcsr & M6800_TRCSR_RE)
{
if (cpustate->trcsr & M6800_TRCSR_WU)
{
// wait for 10 bits of '1'
if (m6800_rx(cpustate) == 1)
{
cpustate->rxbits++;
//logerror("M6800 '%s' Received WAKE UP bit %u\n", cpustate->device->tag(), cpustate->rxbits);
if (cpustate->rxbits == 10)
{
//logerror("M6800 '%s' Receiver Wake Up\n", cpustate->device->tag());
cpustate->trcsr &= ~M6800_TRCSR_WU;
cpustate->rxbits = M6800_SERIAL_START;
}
}
else
{
//logerror("M6800 '%s' Receiver Wake Up interrupted\n", cpustate->device->tag());
cpustate->rxbits = M6800_SERIAL_START;
}
}
else
{
// receive data
switch (cpustate->rxbits)
{
case M6800_SERIAL_START:
@ -797,18 +853,23 @@ static TIMER_CALLBACK(m6800_rx_tick)
{
// start bit found
cpustate->rxbits++;
//logerror("M6800 '%s' Received START bit\n", cpustate->device->tag());
}
break;
case M6800_SERIAL_STOP:
if (m6800_rx(cpustate) == 1)
{
//logerror("M6800 '%s' Received STOP bit\n", cpustate->device->tag());
if (cpustate->trcsr & M6800_TRCSR_RDRF)
{
// overrun error
cpustate->trcsr |= M6800_TRCSR_ORFE;
//logerror("M6800 '%s' Receive Overrun Error\n", cpustate->device->tag());
CHECK_IRQ_LINES(cpustate);
}
else
@ -817,6 +878,8 @@ static TIMER_CALLBACK(m6800_rx_tick)
{
// transfer data into receive register
cpustate->rdr = cpustate->rsr;
//logerror("M6800 '%s' Receive Data Register: %02x\n", cpustate->device->tag(), cpustate->rdr);
// set RDRF flag
cpustate->trcsr |= M6800_TRCSR_RDRF;
@ -828,7 +891,6 @@ static TIMER_CALLBACK(m6800_rx_tick)
else
{
// framing error
if (!(cpustate->trcsr & M6800_TRCSR_ORFE))
{
// transfer unframed data into receive register
@ -838,6 +900,8 @@ static TIMER_CALLBACK(m6800_rx_tick)
cpustate->trcsr |= M6800_TRCSR_ORFE;
cpustate->trcsr &= ~M6800_TRCSR_RDRF;
//logerror("M6800 '%s' Receive Framing Error\n", cpustate->device->tag());
CHECK_IRQ_LINES(cpustate);
}
@ -851,6 +915,8 @@ static TIMER_CALLBACK(m6800_rx_tick)
// receive bit into register
cpustate->rsr |= (m6800_rx(cpustate) << 7);
//logerror("M6800 '%s' Received DATA bit %u: %u\n", cpustate->device->tag(), cpustate->rxbits, BIT(cpustate->rsr, 7));
cpustate->rxbits++;
break;
}
@ -858,6 +924,14 @@ static TIMER_CALLBACK(m6800_rx_tick)
}
}
static TIMER_CALLBACK( sci_tick )
{
m6800_state *cpustate = (m6800_state *)ptr;
serial_transmit(cpustate);
serial_receive(cpustate);
}
/****************************************************************************
* Reset registers to their initial values
****************************************************************************/
@ -883,6 +957,7 @@ static void state_register(m6800_state *cpustate, const char *type)
state_save_register_device_item(cpustate->device, 0, cpustate->port2_data);
state_save_register_device_item(cpustate->device, 0, cpustate->port3_data);
state_save_register_device_item(cpustate->device, 0, cpustate->port4_data);
state_save_register_device_item(cpustate->device, 0, cpustate->port2_written);
state_save_register_device_item(cpustate->device, 0, cpustate->tcsr);
state_save_register_device_item(cpustate->device, 0, cpustate->pending_tcsr);
state_save_register_device_item(cpustate->device, 0, cpustate->irq2);
@ -903,7 +978,9 @@ static void state_register(m6800_state *cpustate, const char *type)
state_save_register_device_item(cpustate->device, 0, cpustate->rxbits);
state_save_register_device_item(cpustate->device, 0, cpustate->txbits);
state_save_register_device_item(cpustate->device, 0, cpustate->txstate);
state_save_register_device_item(cpustate->device, 0, cpustate->trcsr_read);
state_save_register_device_item(cpustate->device, 0, cpustate->trcsr_read_tdre);
state_save_register_device_item(cpustate->device, 0, cpustate->trcsr_read_orfe);
state_save_register_device_item(cpustate->device, 0, cpustate->trcsr_read_rdrf);
state_save_register_device_item(cpustate->device, 0, cpustate->tx);
}
@ -940,6 +1017,7 @@ static CPU_RESET( m6800 )
cpustate->port1_ddr = 0x00;
cpustate->port2_ddr = 0x00;
cpustate->port2_written = 0;
/* TODO: on reset port 2 should be read to determine the operating mode (bits 0-2) */
cpustate->tcsr = 0x00;
cpustate->pending_tcsr = 0x00;
@ -950,12 +1028,15 @@ static CPU_RESET( m6800 )
cpustate->ram_ctrl |= 0x40;
cpustate->trcsr = M6800_TRCSR_TDRE;
cpustate->rmcr = 0;
if (cpustate->m6800_rx_timer) timer_enable(cpustate->m6800_rx_timer, 0);
if (cpustate->m6800_tx_timer) timer_enable(cpustate->m6800_tx_timer, 0);
cpustate->txstate = M6800_TX_STATE_INIT;
cpustate->txbits = cpustate->rxbits = 0;
cpustate->trcsr_read = 0;
cpustate->tx = 1;
cpustate->trcsr_read_tdre = 0;
cpustate->trcsr_read_orfe = 0;
cpustate->trcsr_read_rdrf = 0;
set_rmcr(cpustate, 0);
cpustate->cc = 0xc0;
}
@ -1046,8 +1127,7 @@ static CPU_INIT( m6801 )
cpustate->io = device->space(AS_IO);
cpustate->clock = device->clock() / 4;
cpustate->m6800_rx_timer = timer_alloc(device->machine, m6800_rx_tick, cpustate);
cpustate->m6800_tx_timer = timer_alloc(device->machine, m6800_tx_tick, cpustate);
cpustate->sci_timer = timer_alloc(device->machine, sci_tick, cpustate);
state_register(cpustate, "m6801");
}
@ -1090,8 +1170,7 @@ static CPU_INIT( m6803 )
cpustate->io = device->space(AS_IO);
cpustate->clock = device->clock() / 4;
cpustate->m6800_rx_timer = timer_alloc(device->machine, m6800_rx_tick, cpustate);
cpustate->m6800_tx_timer = timer_alloc(device->machine, m6800_tx_tick, cpustate);
cpustate->sci_timer = timer_alloc(device->machine, sci_tick, cpustate);
state_register(cpustate, "m6803");
}
@ -1145,8 +1224,7 @@ static CPU_INIT( hd63701 )
cpustate->io = device->space(AS_IO);
cpustate->clock = device->clock() / 4;
cpustate->m6800_rx_timer = timer_alloc(device->machine, m6800_rx_tick, cpustate);
cpustate->m6800_tx_timer = timer_alloc(device->machine, m6800_tx_tick, cpustate);
cpustate->sci_timer = timer_alloc(device->machine, sci_tick, cpustate);
state_register(cpustate, "hd63701");
}
@ -1209,20 +1287,32 @@ static READ8_HANDLER( m6803_internal_registers_r )
case 0x01:
return cpustate->port2_ddr;
case 0x02:
return (cpustate->io->read_byte(M6803_PORT1) & (cpustate->port1_ddr ^ 0xff))
if(cpustate->port1_ddr == 0xff)
return cpustate->port1_data;
else
return (cpustate->io->read_byte(M6803_PORT1) & (cpustate->port1_ddr ^ 0xff))
| (cpustate->port1_data & cpustate->port1_ddr);
case 0x03:
return (cpustate->io->read_byte(M6803_PORT2) & (cpustate->port2_ddr ^ 0xff))
if(cpustate->port2_ddr == 0xff)
return cpustate->port2_data;
else
return (cpustate->io->read_byte(M6803_PORT2) & (cpustate->port2_ddr ^ 0xff))
| (cpustate->port2_data & cpustate->port2_ddr);
case 0x04:
return cpustate->port3_ddr;
case 0x05:
return cpustate->port4_ddr;
case 0x06:
return (cpustate->io->read_byte(M6803_PORT3) & (cpustate->port3_ddr ^ 0xff))
if(cpustate->port3_ddr == 0xff)
return cpustate->port3_data;
else
return (cpustate->io->read_byte(M6803_PORT3) & (cpustate->port3_ddr ^ 0xff))
| (cpustate->port3_data & cpustate->port3_ddr);
case 0x07:
return (cpustate->io->read_byte(M6803_PORT4) & (cpustate->port4_ddr ^ 0xff))
if(cpustate->port4_ddr == 0xff)
return cpustate->port4_data;
else
return (cpustate->io->read_byte(M6803_PORT4) & (cpustate->port4_ddr ^ 0xff))
| (cpustate->port4_data & cpustate->port4_ddr);
case 0x08:
cpustate->pending_tcsr = 0;
@ -1265,13 +1355,30 @@ static READ8_HANDLER( m6803_internal_registers_r )
case 0x10:
return cpustate->rmcr;
case 0x11:
cpustate->trcsr_read = 1;
if (cpustate->trcsr & M6800_TRCSR_TDRE)
{
cpustate->trcsr_read_tdre = 1;
}
if (cpustate->trcsr & M6800_TRCSR_ORFE)
{
cpustate->trcsr_read_orfe = 1;
}
if (cpustate->trcsr & M6800_TRCSR_RDRF)
{
cpustate->trcsr_read_rdrf = 1;
}
return cpustate->trcsr;
case 0x12:
if (cpustate->trcsr_read)
if (cpustate->trcsr_read_orfe)
{
cpustate->trcsr_read = 0;
cpustate->trcsr = cpustate->trcsr & 0x3f;
cpustate->trcsr_read_orfe = 0;
cpustate->trcsr &= ~M6800_TRCSR_ORFE;
}
if (cpustate->trcsr_read_rdrf)
{
//logerror("M6801 '%s' Clear RDRF\n", space->cpu->tag());
cpustate->trcsr_read_rdrf = 0;
cpustate->trcsr &= ~M6800_TRCSR_RDRF;
}
return cpustate->rdr;
case 0x13:
@ -1308,7 +1415,7 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
cpustate->port1_ddr = data;
if(cpustate->port1_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT1,cpustate->port1_data);
else
else if (cpustate->port1_ddr)
cpustate->io->write_byte(M6803_PORT1,(cpustate->port1_data & cpustate->port1_ddr)
| (cpustate->io->read_byte(M6803_PORT1) & (cpustate->port1_ddr ^ 0xff)));
}
@ -1317,11 +1424,7 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
if (cpustate->port2_ddr != data)
{
cpustate->port2_ddr = data;
if(cpustate->port2_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT2,cpustate->port2_data);
else
cpustate->io->write_byte(M6803_PORT2,(cpustate->port2_data & cpustate->port2_ddr)
| (cpustate->io->read_byte(M6803_PORT2) & (cpustate->port2_ddr ^ 0xff)));
write_port2(cpustate);
if (cpustate->port2_ddr & 2)
logerror("CPU '%s' PC %04x: warning - port 2 bit 1 set as output (OLVL) - not supported\n",space->cpu->tag(),cpu_get_pc(space->cpu));
@ -1331,24 +1434,14 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
cpustate->port1_data = data;
if(cpustate->port1_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT1,cpustate->port1_data);
else
else if (cpustate->port1_ddr)
cpustate->io->write_byte(M6803_PORT1,(cpustate->port1_data & cpustate->port1_ddr)
| (cpustate->io->read_byte(M6803_PORT1) & (cpustate->port1_ddr ^ 0xff)));
break;
case 0x03:
if (cpustate->trcsr & M6800_TRCSR_TE)
{
cpustate->port2_data = (data & 0xef) | (cpustate->tx << 4);
}
else
{
cpustate->port2_data = data;
}
if(cpustate->port2_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT2,cpustate->port2_data);
else
cpustate->io->write_byte(M6803_PORT2,(cpustate->port2_data & cpustate->port2_ddr)
| (cpustate->io->read_byte(M6803_PORT2) & (cpustate->port2_ddr ^ 0xff)));
cpustate->port2_data = data;
cpustate->port2_written = 1;
write_port2(cpustate);
break;
case 0x04:
if (cpustate->port3_ddr != data)
@ -1356,7 +1449,7 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
cpustate->port3_ddr = data;
if(cpustate->port3_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT3,cpustate->port3_data);
else
else if (cpustate->port3_ddr)
cpustate->io->write_byte(M6803_PORT3,(cpustate->port3_data & cpustate->port3_ddr)
| (cpustate->io->read_byte(M6803_PORT3) & (cpustate->port3_ddr ^ 0xff)));
}
@ -1367,7 +1460,7 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
cpustate->port4_ddr = data;
if(cpustate->port4_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT4,cpustate->port4_data);
else
else if (cpustate->port4_ddr)
cpustate->io->write_byte(M6803_PORT4,(cpustate->port4_data & cpustate->port4_ddr)
| (cpustate->io->read_byte(M6803_PORT4) & (cpustate->port4_ddr ^ 0xff)));
}
@ -1376,7 +1469,7 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
cpustate->port3_data = data;
if(cpustate->port3_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT3,cpustate->port3_data);
else
else if (cpustate->port3_ddr)
cpustate->io->write_byte(M6803_PORT3,(cpustate->port3_data & cpustate->port3_ddr)
| (cpustate->io->read_byte(M6803_PORT3) & (cpustate->port3_ddr ^ 0xff)));
break;
@ -1384,7 +1477,7 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
cpustate->port4_data = data;
if(cpustate->port4_ddr == 0xff)
cpustate->io->write_byte(M6803_PORT4,cpustate->port4_data);
else
else if (cpustate->port4_ddr)
cpustate->io->write_byte(M6803_PORT4,(cpustate->port4_data & cpustate->port4_ddr)
| (cpustate->io->read_byte(M6803_PORT4) & (cpustate->port4_ddr ^ 0xff)));
break;
@ -1429,38 +1522,28 @@ static WRITE8_HANDLER( m6803_internal_registers_w )
logerror("CPU '%s' PC %04x: warning - write %02x to unsupported internal register %02x\n",space->cpu->tag(),cpu_get_pc(space->cpu),data,offset);
break;
case 0x10:
cpustate->rmcr = data & 0x0f;
switch ((cpustate->rmcr & M6800_RMCR_CC_MASK) >> 2)
{
case 0:
case 3: // not implemented
timer_enable(cpustate->m6800_rx_timer, 0);
timer_enable(cpustate->m6800_tx_timer, 0);
break;
case 1:
case 2:
{
int divisor = M6800_RMCR_SS[cpustate->rmcr & M6800_RMCR_SS_MASK];
timer_adjust_periodic(cpustate->m6800_rx_timer, attotime_zero, 0, ATTOTIME_IN_HZ(cpustate->clock / divisor));
timer_adjust_periodic(cpustate->m6800_tx_timer, attotime_zero, 0, ATTOTIME_IN_HZ(cpustate->clock / divisor));
}
break;
}
set_rmcr(cpustate, data);
break;
case 0x11:
if ((data & M6800_TRCSR_TE) && !(cpustate->trcsr & M6800_TRCSR_TE))
{
cpustate->txstate = M6800_TX_STATE_INIT;
cpustate->txbits = 0;
cpustate->tx = 1;
}
if ((data & M6800_TRCSR_RE) && !(cpustate->trcsr & M6800_TRCSR_RE))
{
cpustate->rxbits = 0;
}
cpustate->trcsr = (cpustate->trcsr & 0xe0) | (data & 0x1f);
break;
case 0x13:
if (cpustate->trcsr_read)
//logerror("M6800 '%s' Transmit Data Register: %02x\n", space->cpu->tag(), data);
if (cpustate->trcsr_read_tdre)
{
cpustate->trcsr_read = 0;
cpustate->trcsr_read_tdre = 0;
cpustate->trcsr &= ~M6800_TRCSR_TDRE;
}
cpustate->tdr = data;

12
src/emu/cpu/m6800/m6800.h
View File

@ -22,6 +22,18 @@ enum
/* it is usuali to use PULSE_LINE state */
};
enum
{
M6801_MODE_0 = 0,
M6801_MODE_1,
M6801_MODE_2,
M6801_MODE_3,
M6801_MODE_4,
M6801_MODE_5,
M6801_MODE_6,
M6801_MODE_7
};
/* By default, on a port write port bits which are not set as output in the DDR */
/* are set to the value returned by a read from the same port. If you need to */
/* know the DDR for e.g. port 1, do m6803_internal_registers_r(M6801_DDR1) */