i8257: make the driver handle verify cycles since the dmac only does an address strobe

pc8801: treat verify dma transfers as io write

Author: cracyc

src/devices/machine/i8257.cpp

@@ -158,6 +158,7 @@ inline void i8257_device::dma_read()
 	switch (MODE_TRANSFER_MASK)
 	{
 	case MODE_TRANSFER_VERIFY:
+		break;
 	case MODE_TRANSFER_WRITE:
 		LOGTFR(" - MODE TRANSFER VERIFY/WRITE");
 		m_temp = m_in_ior_cb[m_current_channel](offset);
@@ -185,9 +186,7 @@ inline void i8257_device::dma_write()
 	{
 	case MODE_TRANSFER_VERIFY: {
 		LOGTFR(" - MODE TRANSFER VERIFY");
-		uint8_t v1 = m_in_memr_cb(offset);
-		if(0 && m_temp != v1)
-			logerror("verify error %02x vs. %02x\n", m_temp, v1);
+		m_verify_cb[m_current_channel](offset);
 		break;
 	}
 
@@ -273,6 +272,7 @@ i8257_device::i8257_device(const machine_config &mconfig, const char *tag, devic
 	, m_out_memw_cb(*this)
 	, m_in_ior_cb(*this, 0)
 	, m_out_iow_cb(*this)
+	, m_verify_cb(*this, 0)
 	, m_out_dack_cb(*this)
 {
 }

src/devices/machine/i8257.h

@@ -58,6 +58,7 @@ class i8257_device : public device_t, public device_execute_interface
 	template <unsigned Ch> auto in_ior_cb() { return m_in_ior_cb[Ch].bind(); }
 	template <unsigned Ch> auto out_iow_cb() { return m_out_iow_cb[Ch].bind(); }
 	template <unsigned Ch> auto out_dack_cb() { return m_out_dack_cb[Ch].bind(); }
+	template <unsigned Ch> auto verify_cb() { return m_verify_cb[Ch].bind(); }
 
 	// This should be set for systems that map the DMAC registers into the memory space rather than as I/O ports (e.g. radio86)
 	void set_reverse_rw_mode(bool flag) { m_reverse_rw = flag; }
@@ -105,6 +106,7 @@ class i8257_device : public device_t, public device_execute_interface
 	// channel accessors
 	devcb_read8::array<4> m_in_ior_cb;
 	devcb_write8::array<4> m_out_iow_cb;
+	devcb_read8::array<4> m_verify_cb; // verify sets no rw lines so just pass the address for the driver to handle
 	devcb_write_line::array<4> m_out_dack_cb;
 
 	struct

src/mame/nec/pc8801.cpp

@@ -289,6 +289,13 @@ void pc8801_state::dma_mem_w(offs_t offset, u8 data)
 	m_work_ram[offset & 0xffff] = data;
 }
 
+// the pc8801 appears to just to dma memr and iow cycles if verify mode is set
+uint8_t pc8801_state::dackv(offs_t offset)
+{
+	m_crtc->dack_w(dma_mem_r(offset));
+	return 0;
+}
+
 uint8_t pc8801_state::alu_r(offs_t offset)
 {
 	uint8_t b, r, g;
@@ -1701,6 +1708,7 @@ void pc8801_state::pc8801(machine_config &config)
 	// CH0: 5-inch floppy DMA
 	// CH1: 8-inch floppy DMA, SCSI CD-ROM interface (on MA/MC)
 	m_dma->out_iow_cb<2>().set(m_crtc, FUNC(upd3301_device::dack_w));
+	m_dma->verify_cb<2>().set(FUNC(pc8801_state::dackv));
 	// CH3: <autoload only?>
 
 	TIMER(config, "rtc_timer").configure_periodic(FUNC(pc8801_state::clock_irq_w), attotime::from_hz(600));

src/mame/nec/pc8801.h

@@ -75,6 +75,7 @@ class pc8801_state : public pc8001_base_state
 
 	virtual uint8_t dma_mem_r(offs_t offset) override;
 	void dma_mem_w(offs_t offset, u8 data);
+	uint8_t dackv(offs_t offset);
 
 	virtual uint8_t dictionary_rom_r(offs_t offset);
 	virtual bool dictionary_rom_enable();