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[I8255] Clear output lines to 0 on write to mode register, and float input lines to 1.

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This commit is contained in:
Curt Coder 2010-02-09 10:09:15 +00:00
parent cdd3ee2483
commit f1dfc7b5b3
1 changed files with 46 additions and 2 deletions
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48
src/emu/machine/i8255a.c
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@ -155,6 +155,11 @@ static void output_pc(i8255a_t *i8255a)
{ {
mask |= 0xf0; mask |= 0xf0;
} }
else
{
/* TTL inputs float high */
data |= 0xf0;
}
break; break;
case MODE_1: case MODE_1:
@ -187,6 +192,11 @@ static void output_pc(i8255a_t *i8255a)
{ {
mask |= 0x0f; mask |= 0x0f;
} }
else
{
/* TTL inputs float high */
data |= 0x0f;
}
break; break;
case MODE_1: case MODE_1:
@ -579,6 +589,16 @@ static void set_mode(running_device *device, UINT8 data)
i8255a->inte1 = 0; i8255a->inte1 = 0;
i8255a->inte2 = 0; i8255a->inte2 = 0;
if (port_mode(i8255a, PORT_A) == MODE_OUTPUT)
{
devcb_call_write8(&i8255a->out_port_func[PORT_A], 0, i8255a->output[PORT_A]);
}
else
{
/* TTL inputs float high */
devcb_call_write8(&i8255a->out_port_func[PORT_A], 0, 0xff);
}
if (LOG) logerror("8255A '%s' Group A Mode: %u\n", device->tag.cstr(), group_mode(i8255a, GROUP_A)); if (LOG) logerror("8255A '%s' Group A Mode: %u\n", device->tag.cstr(), group_mode(i8255a, GROUP_A));
if (LOG) logerror("8255A '%s' Port A Mode: %s\n", device->tag.cstr(), (port_mode(i8255a, PORT_A) == MODE_OUTPUT) ? "output" : "input"); if (LOG) logerror("8255A '%s' Port A Mode: %s\n", device->tag.cstr(), (port_mode(i8255a, PORT_A) == MODE_OUTPUT) ? "output" : "input");
if (LOG) logerror("8255A '%s' Port C Upper Mode: %s\n", device->tag.cstr(), (port_c_upper_mode(i8255a) == MODE_OUTPUT) ? "output" : "input"); if (LOG) logerror("8255A '%s' Port C Upper Mode: %s\n", device->tag.cstr(), (port_c_upper_mode(i8255a) == MODE_OUTPUT) ? "output" : "input");
@ -593,6 +613,16 @@ static void set_mode(running_device *device, UINT8 data)
i8255a->obf[PORT_B] = 1; i8255a->obf[PORT_B] = 1;
i8255a->inte[PORT_B] = 0; i8255a->inte[PORT_B] = 0;
if (port_mode(i8255a, PORT_B) == MODE_OUTPUT)
{
devcb_call_write8(&i8255a->out_port_func[PORT_B], 0, i8255a->output[PORT_B]);
}
else
{
/* TTL inputs float high */
devcb_call_write8(&i8255a->out_port_func[PORT_B], 0, 0xff);
}
i8255a->output[PORT_C] = 0; i8255a->output[PORT_C] = 0;
i8255a->input[PORT_C] = 0; i8255a->input[PORT_C] = 0;
@ -717,14 +747,28 @@ READ8_DEVICE_HANDLER( i8255a_pa_r )
{ {
i8255a_t *i8255a = get_safe_token(device); i8255a_t *i8255a = get_safe_token(device);
return i8255a->output[PORT_A]; UINT8 data = 0xff;
if (port_mode(i8255a, PORT_A) == MODE_OUTPUT)
{
data = i8255a->output[PORT_A];
}
return data;
} }
READ8_DEVICE_HANDLER( i8255a_pb_r ) READ8_DEVICE_HANDLER( i8255a_pb_r )
{ {
i8255a_t *i8255a = get_safe_token(device); i8255a_t *i8255a = get_safe_token(device);
return i8255a->output[PORT_B]; UINT8 data = 0xff;
if (port_mode(i8255a, PORT_B) == MODE_OUTPUT)
{
data = i8255a->output[PORT_B];
}
return data;
} }
WRITE_LINE_DEVICE_HANDLER( i8255a_pc2_w ) WRITE_LINE_DEVICE_HANDLER( i8255a_pc2_w )