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im01: add bus error

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This commit is contained in:
hap 2021-12-09 22:46:14 +01:00
parent b1c63d0358
commit d7fb8943ff
1 changed files with 6 additions and 13 deletions
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19
src/mame/drivers/im01.cpp
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@ -17,11 +17,6 @@ TODO:
around 1.1 times faster, maybe К1801ВМ1 internal timing differs from T11,
and/or T11 core timing itself is not 100% accurate.
- verify actual XTAL, the label couldn't be seen
- Bus conflict between RAM and I/O is not understood, ИМ-01(not Т) is picky
about it. It expects RAM 0x003f to be non-0, which only gets set in the
hardware bus error trap routine. But that routine also overwrites the stack,
so I don't think that's it. Another hint that points to a bus conflict is
that the game clears RAM 0x003e before reading inputs.
- is ИМ-01Т extra RAM chip used at all?
*******************************************************************************
@ -80,7 +75,6 @@ public:
m_maincpu(*this, "maincpu"),
m_display(*this, "display"),
m_dac(*this, "dac"),
m_ram(*this, "ram"),
m_inputs(*this, "IN.%u", 0)
{ }
@ -94,7 +88,6 @@ private:
required_device<t11_device> m_maincpu;
required_device<pwm_display_device> m_display;
required_device<dac_bit_interface> m_dac;
required_shared_ptr<u16> m_ram;
required_ioport_array<6> m_inputs;
void main_map(address_map &map);
@ -109,7 +102,7 @@ private:
u16 digit_r(offs_t offset, u16 mem_mask);
void digit_w(offs_t offset, u16 data, u16 mem_mask);
u16 input_r(offs_t offset, u16 mem_mask);
u16 conflict_r(offs_t offset, u16 mem_mask);
void error_w(offs_t offset, u16 data, u16 mem_mask);
u16 m_inp_mux = 0;
u16 m_digit_data = 0;
@ -194,11 +187,10 @@ u16 im01_state::input_r(offs_t offset, u16 mem_mask)
return data << 8;
}
u16 im01_state::conflict_r(offs_t offset, u16 mem_mask)
void im01_state::error_w(offs_t offset, u16 data, u16 mem_mask)
{
// bus conflict between RAM and I/O
u16 conflict = (offset >= 0x18 && offset < 0x20) ? 0xff : 0;
return m_ram[offset] | conflict;
// unmapped port, expects a bus error
m_maincpu->pulse_input_line(t11_device::BUS_ERROR, attotime::zero);
}
@ -209,11 +201,12 @@ u16 im01_state::conflict_r(offs_t offset, u16 mem_mask)
void im01_state::main_map(address_map &map)
{
map(0x0000, 0x07ff).ram().r(FUNC(im01_state::conflict_r)).share("ram");
map(0x0000, 0x07ff).ram();
map(0x2000, 0x5fff).rom();
map(0xe030, 0xe031).mirror(0x1800).rw(FUNC(im01_state::mux_r), FUNC(im01_state::mux_w));
map(0xe03c, 0xe03d).mirror(0x1800).rw(FUNC(im01_state::digit_r), FUNC(im01_state::digit_w));
map(0xe03e, 0xe03f).mirror(0x1800).r(FUNC(im01_state::input_r));
map(0xffe8, 0xffe9).w(FUNC(im01_state::error_w)).nopr();
}