rm/rm380z.cpp: Correct floppy disk handling so double sided disks work and also add support for 8 inch disks

[RobinSergeant]

Double sided disks would not load before because the floppy drives were wrongly configured as single sided. The wrong control port bit was also being used to select the side. After fixing this I can load more software and access the second side of double sided disks (logical drives C: and D:).

I've also added support for 8 inch disks used by the /F firmware variants such as "COS 3.4D/F". The "/F" refers to FDS (Full Disc System - 8") as opposed to MDS (Mini Disc System - 5.25"), which is designated by "/M".

FDS and MDS actually use different ports, so I've also updated the IO port map to include both sets. The firmware guide shows both as being reserved for FDC use. NB the control port address is not fully decoded and can actually be written to using 4 addresses which is why I've expanded this.

I have tested various double sided MDS disks, but have not been able to test FDS as there don't seem to be any 8" disk dumps available. However, it does now show the "Disk not ready" message when trying to boot without a disk (previously nothing happened when trying to boot with COS 3.4D).

[cuavas]

Will it work if you do this?

	map(0xc4, 0xc7).mirror(0x20).w(FUNC(rm380z_state::disk_0_control));
	map(0xe0, 0xe3).rw(m_fdc, FUNC(fd1771_device::read), FUNC(fd1771_device::write));
	map(0xe8, 0xff).rw(FUNC(rm380z_state::rm380z_porthi_r), FUNC(rm380z_state::rm380z_porthi_w));

That way it’s clearer that it’s ignoring A5 for that handler.

[RobinSergeant]

Yes, that works. Thank you.

[cuavas]

You should use m_floppy0 and m_floppy1 in place of the literal tags here.

[RobinSergeant]

Done.

[cuavas]

In general you should avoid replacing devices unnecessarily and just

Can you just reconfigure the devices here? If you make the other change to not use literal tags, something like:

	m_floppy0->option_reset();
	rm380z_fds_floppies(*m_floppy0);
	m_floppy0->set_default_option("fds");
	m_floppy1->option_reset();
	rm380z_fds_floppies(*m_floppy1);
	m_floppy1->set_default_option("fds");

Alternatively, you could have both drives in one set of options, and make the slots fixed to prevent the user from selecting the wrong type:

static void rm380z_floppies(device_slot_interface &device)
{
	device.option_add("mds", FLOPPY_525_SD);
	device.option_add("fds", FLOPPY_8_DSSD);
}

…

	FLOPPY_CONNECTOR(config, m_floppy0, rm380z_floppies, "mds", floppy_image_device::default_mfm_floppy_formats).set_fixed(true);
	FLOPPY_CONNECTOR(config, m_floppy1, rm380z_floppies, "mds", floppy_image_device::default_mfm_floppy_formats).set_fixed(true);

…

void rm380z_state_cos34::configure_fds(machine_config &config)
{
	rm380z_state_cos34::configure(config);

	m_floppy0->set_default_option("fds");
	m_floppy1->set_default_option("fds");
}

[RobinSergeant]

Good idea, I've gone with your second alternative as that seems cleaner.

[RobinSergeant]

Thanks for reviewing @cuavas. I've now addressed your comments.