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hd6120: Improve sequencing for OPR group 1

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This commit is contained in:
AJR 2021-10-11 17:21:30 -04:00
parent c4e8f00006
commit 220432c61b
1 changed files with 15 additions and 13 deletions
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28
src/devices/cpu/pdp8/hd6120.cpp
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@ -664,27 +664,29 @@ void hd6120_device::execute_run()
case minor_state::OP1_1:
m_pc = m_temp & 07777;
m_temp = (BIT(m_ir, 7) ? 0 : m_ac) ^ (BIT(m_ir, 5) ? 07777 : 0);
if (BIT(m_ir, 0))
{
++m_temp;
if (m_temp >= 010000)
m_flags ^= 4; // LINK is complemented upon carry out
}
m_temp = (BIT(m_ir, 7) ? 0 : m_ac) ^ (BIT(m_ir, 5) ? 07777 : 0); // CLA and/or CMA
if (BIT(m_ir, 6))
m_flags &= 3; // CLL
if (BIT(m_ir, 4))
m_flags ^= 4; // CML
m_state = minor_state::OP1_2;
break;
case minor_state::OP1_2:
m_ac = m_temp & 07777;
if (BIT(m_ir, 6))
m_flags &= 3;
if (BIT(m_ir, 4))
m_flags ^= 4;
if (BIT(m_ir, 0))
{
++m_temp; // IAC
if (m_temp == 010000)
{
m_flags ^= 4; // LINK is complemented upon carry out
m_temp = 0;
}
}
m_state = minor_state::OP1_3;
break;
case minor_state::OP1_3:
m_temp = rotate_step(m_ac);
m_temp = rotate_step(m_temp);
if (BIT(m_ir, 1))
m_state = minor_state::OP1_4;
else