[Coco] MAME FDC Issue that can cause corruption

[Barry Nelson]

I think it might have to with these changes…

85  src/emu/bus/coco/coco_fdc.c
 @@ -291,16 +298,17 @@ void coco_fdc_device::dskreg_w(UINT8 data)
        else if (data & 0x40)
                drive = 3;

-       legacy_floppy_image_device *floppy[4];
+       floppy_image_device *floppy[4];

-       floppy[0] = subdevice<legacy_floppy_image_device>(FLOPPY_0);
-       floppy[1] = subdevice<legacy_floppy_image_device>(FLOPPY_1);
-       floppy[2] = subdevice<legacy_floppy_image_device>(FLOPPY_2);
-       floppy[3] = subdevice<legacy_floppy_image_device>(FLOPPY_3);
+       floppy[0] = subdevice<floppy_connector>(WD_TAG ":0")->get_device();
+       floppy[1] = subdevice<floppy_connector>(WD_TAG ":1")->get_device();
+       floppy[2] = subdevice<floppy_connector>(WD_TAG ":2")->get_device();
+       floppy[3] = subdevice<floppy_connector>(WD_TAG ":3")->get_device();

        for (int i = 0; i < 4; i++)
        {       
-               floppy[i]->floppy_mon_w(i == drive ? CLEAR_LINE : ASSERT_LINE);
+               if (floppy[i])
+                       floppy[i]->mon_w(i == drive ? CLEAR_LINE : ASSERT_LINE);
        }

        head = ((data & 0x40) && (drive != 3)) ? 1 : 0;
 @@ -309,8 +317,11 @@ void coco_fdc_device::dskreg_w(UINT8 data)

        update_lines();

-       m_wd17xx->set_drive(drive);
-       m_wd17xx->set_side(head);
+       m_wd17xx->set_floppy(floppy[drive]);
+
+       if (floppy[drive])
+               floppy[drive]->ss_w(head);
+
        m_wd17xx->dden_w(!BIT(m_dskreg, 5));
 }

 @@ -379,7 +390,7 @@ WRITE8_MEMBER(coco_fdc_device::write)
                        dskreg_w(data);
                        break;
                case 8:
-                       m_wd17xx->command_w(space, 0, data);
+                       m_wd17xx->cmd_w(space, 0, data);
                        break;
                case 9:
                        m_wd17xx->track_w(space, 0, data);
 @@ -388,6 +399,7 @@ WRITE8_MEMBER(coco_fdc_device::write)
                        m_wd17xx->sector_w(space, 0, data);
                        break;
                case 11:
+                       //printf("data w %02x\n", data);
                        m_wd17xx->data_w(space, 0, data);
                        break;
        };
 @@ -413,10 +425,12 @@ WRITE8_MEMBER(coco_fdc_device::write)
 //**************************************************************************

 static MACHINE_CONFIG_FRAGMENT(dragon_fdc)
-       MCFG_DEVICE_ADD(WD2797_TAG, WD2797, 0)
-       MCFG_WD17XX_DEFAULT_DRIVE4_TAGS
+       MCFG_WD2797_ADD(WD2797_TAG, XTAL_1MHz)

-       MCFG_LEGACY_FLOPPY_4_DRIVES_ADD(coco_floppy_interface)
+       MCFG_FLOPPY_DRIVE_ADD(WD2797_TAG ":0", coco_fdc_floppies, "qd", coco_fdc_device::floppy_formats)
+       MCFG_FLOPPY_DRIVE_ADD(WD2797_TAG ":1", coco_fdc_floppies, "qd", coco_fdc_device::floppy_formats)
+       MCFG_FLOPPY_DRIVE_ADD(WD2797_TAG ":2", coco_fdc_floppies, "", coco_fdc_device::floppy_formats)
+       MCFG_FLOPPY_DRIVE_ADD(WD2797_TAG ":3", coco_fdc_floppies, "", coco_fdc_device::floppy_formats)
 MACHINE_CONFIG_END


 @@ -511,10 +525,20 @@ void dragon_fdc_device::dskreg_w(UINT8 data)
                        data);
        }

-       if (data & 0x04)
-               m_wd2797->set_drive(data & 0x03);
+       floppy_image_device *floppy = NULL;
+
+       switch (data & 0x03)
+       {
+       case 0: floppy = subdevice<floppy_connector>(WD2797_TAG ":0")->get_device(); break;
+       case 1: floppy = subdevice<floppy_connector>(WD2797_TAG ":1")->get_device(); break;
+       case 2: floppy = subdevice<floppy_connector>(WD2797_TAG ":2")->get_device(); break;
+       case 3: floppy = subdevice<floppy_connector>(WD2797_TAG ":3")->get_device(); break;
+       }
+
+       m_wd2797->set_floppy(floppy);

        m_wd2797->dden_w(BIT(data, 3));
+
        m_dskreg = data;
 }

 @@ -556,12 +580,7 @@ WRITE8_MEMBER(dragon_fdc_device::write)
        switch(offset & 0xEF)
        {
                case 0:
-                       m_wd2797->command_w(space, 0, data);
-
-                       /* disk head is encoded in the command byte */
-                       /* Only for type 3 & 4 commands */
-                       if (data & 0x80)
-                               m_wd2797->set_side((data & 0x02) ? 1 : 0);
+                       m_wd2797->cmd_w(space, 0, data);
                        break;
                case 1:
                        m_wd2797->track_w(space, 0, data);