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sinclair/specnext.cpp: Expansion bus control #14328

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sinclair/specnext.cpp: Expansion bus control #14328

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16 changes: 9 additions & 7 deletions src/mame/sinclair/specnext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,7 @@ class specnext_state : public spectrum_128_state
specnext_state(const machine_config &mconfig, device_type type, const char *tag)
: spectrum_128_state(mconfig, type, tag)
, m_maincpu(*this, "maincpu")
, m_io_shadow_view(*this, "io_shadow_view")
, m_io_expbus_view(*this, "io_expbus_view")
, m_bank_boot_rom(*this, "bootrom")
, m_bank_ram(*this, "bank_ram%u", 0U)
, m_view0(*this, "mem_view0")
Expand Down Expand Up @@ -252,6 +252,8 @@ class specnext_state : public spectrum_128_state
void nr_70_layer2_palette_offset_w(u8 data) { m_nr_70_layer2_palette_offset = data; m_layer2->palette_offset_w(m_nr_70_layer2_palette_offset); }
void nr_71_layer2_scrollx_msb_w(bool data) { m_nr_71_layer2_scrollx_msb = data; m_layer2->scroll_x_w((m_nr_71_layer2_scrollx_msb << 8) | m_nr_16_layer2_scrollx); }

void nr_80_expbus_w(u8 data) { m_nr_80_expbus = data; m_io_expbus_view.select(BIT(m_nr_80_expbus, 7)); }

bool nr_8c_altrom_en() const { return BIT(m_nr_8c_altrom, 7); }
bool nr_8c_altrom_rw() const { return BIT(m_nr_8c_altrom, 6); }
bool nr_8c_altrom_lock_rom1() const { return BIT(m_nr_8c_altrom, 5); }
Expand Down Expand Up @@ -314,7 +316,7 @@ class specnext_state : public spectrum_128_state
void port_e7_reg_w(u8 data);

memory_access<8, 0, 0, ENDIANNESS_LITTLE>::specific m_next_regs;
memory_view m_io_shadow_view;
memory_view m_io_expbus_view;
memory_bank_creator m_bank_boot_rom;
memory_bank_array_creator<8> m_bank_ram;
memory_view m_view0, m_view1, m_view2, m_view3, m_view4, m_view5, m_view6, m_view7;
Expand Down Expand Up @@ -2190,7 +2192,7 @@ void specnext_state::reg_w(offs_t nr_wr_reg, u8 nr_wr_dat)
m_nr_7f_user_register_0 = nr_wr_dat;
break;
case 0x80:
m_nr_80_expbus = nr_wr_dat;
nr_80_expbus_w(nr_wr_dat);
break;
case 0x81:
m_nr_81_expbus_ula_override = BIT(nr_wr_dat, 6);
Expand Down Expand Up @@ -2929,9 +2931,9 @@ void specnext_state::map_io(address_map &map)
m_dac[3]->data_w(data);
}));

map(0x0000, 0xffff).view(m_io_shadow_view);
subdevice<zxbus_device>("zxbus")->set_io_space(m_io_shadow_view[0], m_io_shadow_view[1]);
m_io_shadow_view.select(0);
map(0x0000, 0xffff).view(m_io_expbus_view);
m_io_expbus_view[0]; // exp bus disabled
subdevice<zxbus_device>("zxbus")->set_io_space(m_io_expbus_view[1], m_io_expbus_view[1]);
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@galibert galibert Oct 22, 2025

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Vas, how iffy is that? I'm not at all sure of the state of initialization of subdevices at that point in the startup.

}

void specnext_state::map_regs(address_map &map)
Expand Down Expand Up @@ -3357,7 +3359,7 @@ void specnext_state::machine_reset()
//nmi_divmmc = 0;
//nmi_expbus = 0;
//nmi_state = S_NMI_IDLE;
m_nr_80_expbus = (m_nr_80_expbus << 4) | (m_nr_80_expbus & 0x0f);
nr_80_expbus_w((m_nr_80_expbus << 4) | (m_nr_80_expbus & 0x0f));
m_nr_8c_altrom = (m_nr_8c_altrom << 4) | (m_nr_8c_altrom & 0x0f);
//port_253b_rd_qq = 0b00;
//sram_req_d = 0;
Expand Down
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