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[icebox] Add INTRQ handler so that disk routines can work properly

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(for example: Command '220 LOAD' now works with disk GORF8102.IMD)
This commit is contained in:
Frank Palazzolo 2019-06-30 19:53:03 -04:00
parent 500ca5b8fc
commit f685eff104
1 changed files with 13 additions and 1 deletions
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14
src/mame/drivers/icebox.cpp
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@ -108,6 +108,9 @@ on the boards to say which of the four selects it responds to.
The three byte fifo and a register jams a zero onto the data bus (when?), and we have the source for the CP/M version
of the debugger/boot prom to see how interrupt handling occurs.
When the floppy controller generates a DRQ or INTRQ it also generates a Z80 INT, which uses IM 0
and forces a NOP (00) onto the bus. This allows firmware and/or disk routines to resume after a HALT.
I can sort of piece together what Terse implements and what it evolved from. I think it started as the Caltech FORTH
implemented for the PDP-10 and 11 with a lot of words stripped out, and others added. This was submitted to DECUS as
submission 11-232 but much of the early DECUS stuff has been lost, so I've not been able to find a copy to see how the
@ -176,6 +179,7 @@ public:
private:
DECLARE_WRITE_LINE_MEMBER(drq_w);
DECLARE_WRITE_LINE_MEMBER(intrq_w);
void mem_map(address_map &map);
void io_map(address_map &map);
void machine_reset() override;
@ -286,13 +290,20 @@ void icebox_state::port_f1_w(u8 data)
m_fdc->dden_w(1); // single density?
}
// The next byte from floppy is available. Enable CPU so it can get the byte, via IM0.
// The next byte from floppy is available. Enable CPU so it can get the NOP byte, via IM0.
WRITE_LINE_MEMBER(icebox_state::drq_w)
{
if (BIT(m_f1, 2))
m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, state ? ASSERT_LINE : CLEAR_LINE, 0x00); // Z80
}
// The next byte from floppy is available. Enable CPU so it can get the NOP byte, via IM0.
WRITE_LINE_MEMBER(icebox_state::intrq_w)
{
if (BIT(m_f1, 2))
m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, state ? ASSERT_LINE : CLEAR_LINE, 0x00); // Z80
}
static void floppies(device_slot_interface &device)
{
device.option_add("flop", FLOPPY_8_SSDD); // Pertec "iCOM FD5200"
@ -343,6 +354,7 @@ void icebox_state::icebox(machine_config &config)
FD1771(config, m_fdc, 4_MHz_XTAL / 2);
m_fdc->drq_wr_callback().set(FUNC(icebox_state::drq_w));
m_fdc->intrq_wr_callback().set(FUNC(icebox_state::intrq_w));
FLOPPY_CONNECTOR(config, m_floppy0, floppies, "flop", floppy_image_device::default_floppy_formats).enable_sound(true);
FLOPPY_CONNECTOR(config, m_floppy1, floppies, "flop", floppy_image_device::default_floppy_formats).enable_sound(true);
}