Skip to content

sinclair/specnext.cpp Added extra memory read wait state at 28MHz #13869

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Jul 21, 2025
+33 −3
Merged

sinclair/specnext.cpp Added extra memory read wait state at 28MHz #13869

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
ac2478c
sinclair/specnext.cpp Added extra memory read wait state at 28MHz
holub Jun 21, 2025
0ec75dc
Merge branch 'master' of https://github.com/mamedev/mame into next
holub Jul 4, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 6 additions & 2 deletions src/devices/machine/z80dma.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -179,6 +179,7 @@ void z80dma_device::device_start()
save_item(NAME(m_rdy));
save_item(NAME(m_force_ready));
save_item(NAME(m_wait));
save_item(NAME(m_waits_extra));
save_item(NAME(m_busrq_ack));
save_item(NAME(m_is_pulse));
save_item(NAME(m_latch));
Expand All @@ -197,6 +198,7 @@ void z80dma_device::device_reset()
m_rdy = 0;
m_force_ready = 0;
m_wait = 0;
m_waits_extra = 0;
m_num_follow = 0;
m_read_num_follow = m_read_cur_follow = 0;
m_reset_pointer = 0;
Expand Down Expand Up @@ -497,7 +499,8 @@ TIMER_CALLBACK_MEMBER(z80dma_device::clock_w)
}

const attotime clock = clocks_to_attotime(1);
const attotime next = clock * (3 - ((PORTA_IS_SOURCE ? PORTA_TIMING : PORTB_TIMING) & 0x03));
const attotime next = clock * (3 - ((PORTA_IS_SOURCE ? PORTA_TIMING : PORTB_TIMING) & 0x03) + m_waits_extra);
m_waits_extra = 0;
m_timer->adjust(next, 0, clock);

m_dma_seq = SEQ_TRANS1_READ_SOURCE;
Expand All @@ -517,7 +520,8 @@ TIMER_CALLBACK_MEMBER(z80dma_device::clock_w)
case SEQ_TRANS1_INC_DEC_DEST_ADDRESS:
{
const attotime clock = clocks_to_attotime(1);
const attotime next = clock * (3 - ((PORTB_IS_SOURCE ? PORTA_TIMING : PORTB_TIMING) & 0x03));
const attotime next = clock * (3 - ((PORTB_IS_SOURCE ? PORTA_TIMING : PORTB_TIMING) & 0x03) + m_waits_extra);
m_waits_extra = 0;
m_timer->adjust(next, 0, clock);

m_dma_seq = SEQ_TRANS1_WRITE_DEST;
Expand Down
2 changes: 2 additions & 0 deletions src/devices/machine/z80dma.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ class z80dma_device : public device_t,
void iei_w(int state) { m_iei = state; interrupt_check(); }
void rdy_w(int state);
void wait_w(int state) { m_wait = state; }
void adjust_wait(int count) { m_waits_extra += count; }
void bai_w(int state);

protected:
Expand Down Expand Up @@ -153,6 +154,7 @@ class z80dma_device : public device_t,
u8 m_reset_pointer;

int m_wait;
int m_waits_extra;
int m_busrq_ack;
bool m_is_pulse;
u8 m_latch;
Expand Down
26 changes: 25 additions & 1 deletion src/mame/sinclair/specnext.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,7 @@ class specnext_state : public spectrum_128_state
void mmu_x2_w(offs_t bank, u8 data);
u8 dma_r(bool dma_mode);
void dma_w(bool dma_mode, u8 data);
u8 dma_mreq_r(offs_t offset);
u8 spi_data_r();
void spi_data_w(u8 data);
void spi_miso_w(u8 data);
Expand Down Expand Up @@ -1154,6 +1155,15 @@ void specnext_state::dma_w(bool dma_mode, u8 data)
m_dma->write(data);
}

u8 specnext_state::dma_mreq_r(offs_t offset)
{
if (m_nr_07_cpu_speed == 0b11)
{
m_dma->adjust_wait(1);
}
return m_program.read_byte(offset);
}

u8 specnext_state::reg_r(offs_t nr_register)
{
u8 port_253b_dat;
Expand Down Expand Up @@ -2405,6 +2415,12 @@ void specnext_state::map_fetch(address_map &map)
approach gives better experience in debugger UI. */
do_m1(offset);
m_divmmc_delayed_check = 0;

// do_m1 performs read from m_program with waits, we need to take it back
if (!machine().side_effects_disabled() && (m_nr_07_cpu_speed == 0b11))
{
m_maincpu->adjust_icount(1);
}
}

return m_program.read_byte(offset);
Expand Down Expand Up @@ -3426,6 +3442,14 @@ void specnext_state::video_start()
to[offset & 0x1fff] = data;
}
});
prg.install_read_tap(0x0000, 0xffff, "mem_wait_r", [this](offs_t offset, u8 &data, u8 mem_mask)
{
// The 28MHz with core 3.0.5 is adding extra wait state to every instruction opcode fetch and memory read
if (!machine().side_effects_disabled() && (m_nr_07_cpu_speed == 0b11))
{
m_maincpu->adjust_icount(-1);
}
});
}

void specnext_state::tbblue(machine_config &config)
Expand Down Expand Up @@ -3453,7 +3477,7 @@ void specnext_state::tbblue(machine_config &config)
SPECNEXT_DMA(config, m_dma, 28_MHz_XTAL / 8);
m_dma->out_busreq_callback().set_inputline(m_maincpu, Z80_INPUT_LINE_BUSRQ);
m_dma->out_int_callback().set_inputline(m_maincpu, INPUT_LINE_IRQ0);
m_dma->in_mreq_callback().set([this](offs_t offset) { return m_program.read_byte(offset); });
m_dma->in_mreq_callback().set(FUNC(specnext_state::dma_mreq_r));
m_dma->out_mreq_callback().set([this](offs_t offset, u8 data) { m_program.write_byte(offset, data); });
m_dma->in_iorq_callback().set([this](offs_t offset) { return m_io.read_byte(offset); });
m_dma->out_iorq_callback().set([this](offs_t offset, u8 data) { m_io.write_byte(offset, data); });
Expand Down
Loading