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am9517a: revert these changes which break the qx10 and pc9801 which use active low dreq (nw)

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This commit is contained in:
cracyc 2018-10-28 18:19:54 -05:00
parent b824de9530
commit f403a46c07
1 changed files with 4 additions and 21 deletions
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25
src/devices/machine/am9517a.cpp
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@ -817,22 +817,9 @@ WRITE8_MEMBER( am9517a_device::write )
switch (offset & 0x0f)
{
case REGISTER_COMMAND:
{
bool old_dack_active_high = COMMAND_DACK_ACTIVE_HIGH;
bool old_dreq_active_low = COMMAND_DREQ_ACTIVE_LOW;
m_command = data;
LOG("AM9517A Command Register: %02x\n", m_command);
m_command = data;
if (old_dack_active_high != COMMAND_DACK_ACTIVE_HIGH)
{
set_dack(); // Line values for DACK changed, update them to reflect the new state.
}
if (old_dreq_active_low != COMMAND_DREQ_ACTIVE_LOW)
{
// Invert the request bits because the interpretation of line levels has changed
m_status ^= 0xF0;
}
}
LOG("AM9517A Command Register: %02x\n", m_command);
break;
case REGISTER_REQUEST:
@ -894,12 +881,8 @@ WRITE8_MEMBER( am9517a_device::write )
case REGISTER_MASTER_CLEAR:
LOG("AM9517A Master Clear\n");
{
// Even the master reset should not clear the state of the input lines.
int stored_status = m_status;
device_reset();
m_status = stored_status & 0xF0;
}
device_reset();
break;
case REGISTER_CLEAR_MASK: