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z8: Add Z8682 type with (fake) internal ROM; prevent timer from endlessly thrashing with a count of 1

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This commit is contained in:
AJR 2019-01-17 19:49:27 -05:00
parent a527525e52
commit 326a93f937
2 changed files with 36 additions and 3 deletions
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26
src/devices/cpu/z8/z8.cpp
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@ -119,6 +119,7 @@ DEFINE_DEVICE_TYPE(UB8830D, ub8830d_device, "ub8830d", "UB8830D")
DEFINE_DEVICE_TYPE(Z8611, z8611_device, "z8611", "Zilog Z8611")
DEFINE_DEVICE_TYPE(Z8671, z8671_device, "z8671", "Zilog Z8671")
DEFINE_DEVICE_TYPE(Z8681, z8681_device, "z8681", "Zilog Z8681")
DEFINE_DEVICE_TYPE(Z8682, z8682_device, "z8682", "Zilog Z8682")
/***************************************************************************
@ -215,6 +216,23 @@ z8681_device::z8681_device(const machine_config &mconfig, const char *tag, devic
}
z8682_device::z8682_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: z8_device(mconfig, Z8682, tag, owner, clock, 0x800, true)
{
}
ROM_START(z8682)
// Zilog admits that this nominally ROMless type uses a "small internal ROM"
ROM_REGION(0x0800, "internal", 0)
ROM_LOAD("z8682.bin", 0x0000, 0x0800, CRC(37525bc8) SHA1(3ce6251d647c4af4a7cbd854f6de1b4027c9f27a) BAD_DUMP) // hand-crafted bootstrap
ROM_END
const tiny_rom_entry *z8682_device::device_rom_region() const
{
return ROM_NAME(z8682);
}
std::unique_ptr<util::disasm_interface> z8_device::create_disassembler()
{
return std::make_unique<z8_disassembler>();
@ -845,7 +863,8 @@ TIMER_CALLBACK_MEMBER( z8_device::t0_tick )
if (m_count[0] == 0)
{
m_count[0] = m_t[0];
m_t0_timer->adjust(attotime::zero, 0, cycles_to_attotime(4 * ((m_pre[0] >> 2) + 1)));
attotime period = cycles_to_attotime(4 * ((m_pre[0] >> 2) + 1));
m_t0_timer->adjust(period, 0, period);
m_t0_timer->enable(m_pre[0] & Z8_PRE0_COUNT_MODULO_N);
request_interrupt(4);
}
@ -858,8 +877,9 @@ TIMER_CALLBACK_MEMBER( z8_device::t1_tick )
if (m_count[1] == 0)
{
m_count[1] = m_t[1];
m_t1_timer->adjust(attotime::zero, 0, cycles_to_attotime(4 * ((m_pre[1] >> 2) + 1)));
m_t1_timer->enable(m_pre[1] & Z8_PRE0_COUNT_MODULO_N);
attotime period = cycles_to_attotime(4 * ((m_pre[1] >> 2) + 1));
m_t1_timer->adjust(period, 0, period);
m_t1_timer->enable(m_pre[1] & Z8_PRE1_COUNT_MODULO_N);
request_interrupt(5);
}
}

13
src/devices/cpu/z8/z8.h
View File

@ -396,6 +396,16 @@ public:
};
class z8682_device : public z8_device
{
public:
z8682_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
protected:
const tiny_rom_entry *device_rom_region() const override;
};
// Zilog Z8601
DECLARE_DEVICE_TYPE(Z8601, z8601_device)
@ -411,4 +421,7 @@ DECLARE_DEVICE_TYPE(Z8671, z8671_device)
// Zilog Z8681 ROMless
DECLARE_DEVICE_TYPE(Z8681, z8681_device)
// Zilog Z8682 ROMless (boot to 0812H)
DECLARE_DEVICE_TYPE(Z8682, z8682_device)
#endif // MAME_CPU_Z8_Z8_H